The Pantera Place
"Your de Tomaso Connection"

Air Conditioning System Upgrade

By Mike Dailey

June 17, 2001

The original Pantera air conditioning system used a Ford, York style, piston type, compressor. The system worked pretty well for the cars in seventies and most of the magazine reviews didn't have any negative comments. When I bought my Pantera in 1998 the A/C worked and held the R-12 refrigerant OK, but the compressor crankcase leaked oil so I haven't used it very much. The other problem is that the engine does not have a fast idle solenoid to speed-up the engine idle when the compressor is running so the compressor load would slow the idle too much.  The York style compressor takes some significant HP from the engine to run.

Some of the Pantera owners that have the stock compressors think that they may work better than the new rotary type compressors and they could be right.  For many people the York compressor is a great solution.  With that in mind my first approach was to buy a refurbished Ford, York style compressor from NAPA auto parts for $95.  I was thinking about a low buck approach to repair the system because I don't use it very much.  After more thought and realizing that, more than just the compressor would need to be replaced, I changed my mind and ordered a Sanden SD-508 R-12 rotary type compressor from Pantera East. To install the compressor an adapter bracket must be used to mount the new compressor on the original mount.

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View of the Pantera East Sanden SD-508 R-12 rotary type compressor.  The compressor can also be used with R-134 but this one was ordered with R-12 service fittings. 

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View of the Pantera East adapter bracket.  The bracket is a very nicely made, machined aluminum unit. 

The next step was checking out the existing system.  I ran the system for awhile to check it out and found that it still worked but from the sight glass I could see that the system was low on R-12.   The sight glass is located on the top of the receiver dryer.  With the system running only a few bubbles should be moving by the glass.   A lot of bubbles indicates low R-12.

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View of the receiver dryer.  It is mounted in the back of the engine bay next to the condenser shroud. The clear hose visible in the image is the coolant overflow tank vent.

The next step was cleaning the condenser.  I put a plastic tarp in the engine bay and padded the area with old news papers.  I removed the four bolts holding the condenser and moved it back so I could have access to the back side of the condenser and placed the fan side of the unit on the news papers.   I sprayed 409 cleaner on the condenser and scrubbed it lightly with a brush.  I then sprayed it with water and then blew it out from the fan side with compressed air.  There wasn't much to clean, but I wanted to make sure it was completely clean.  I gave the back side condenser fins a very, very light coat of flat black paint because it is visible from the back of the car.  There was some oil in the lower corner of the condenser and on the lower A/C hose.   Oil on the A/C parts is an indication of a R-12 leak.   I'm not sure if it is the condenser or the hose connection.  I ran the A/C system some more after I cleaned the condenser and hose and did not see any more oil. 

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View of the condenser and condenser fan

The next step is finding an A/C shop to do the A/C work.   I plan to remove the old compressor without removing the hoses from it and move it out of the way and temporally wire it to the frame rail of the car.  I don't want to vent the R-12 because it is super expensive and also I think it is illegal to vent R-12 into the atmosphere.  Then I plan on installing the new compressor myself.   I don't want the A/C shop messing with the compressor installation and the inside of the car.  After I get it installed I'll drive the car to the A/C shop.

I hope to install the new compressor myself and have the A/C shop evacuate the system of the existing R12, install a new receiver dryer, install a new hose from the compressor to the condenser, a new hose from the condenser to the receiver dryer, remove the old compressor and hook up the hoses to the new compressor.   I would like reuse the hoses that connect  to the evaporator because they run through the passenger side rocker panel on the 71 cars and are not fun to replace.  I'm also hoping that the expansion valve is OK that is located up front with the evaporator.  After all of the hoses are in installed by the A/C shop the system is then evacuated for at least 30 minutes and tested for leaks.  If the system holds a vacuum the system can then be charged with R-12.   Some shops have equipment for cleaning and scrubbing your existing R-12 and recharging the system with your R-12.   After the system is charged with R-12 the system is checked for operation.  I want to see if I can find a shop that can supply a receiver dryer that has a pressure switch so I can add it to the compressor relay logic that will shut down the system if too much pressure builds up in the condenser.   I've also located a new condenser and I'm debating if I should replace it too.   The condenser fan tends to suck in exhaust fumes that corrode the condenser fins where they contact the tubes.  This causes the condenser to loose efficacy, but my condenser looks good from the outside.   

One other item I had to fix was a bolt that was used for the back mount of the compressor bracket.  Someone back in 1991, when the new engine was installed, used a bolt that was too long and bottomed it out in the treads of the block.  After three days of soaking it with penetrating oil and having no luck, I ended up using my air impact wrench on the lowest setting to get it loose.  It was hard getting the heavy impact wrench, two U joints and extensions around the headers, motor mounts, etc. I let the impact wrench bang on the bolt for awhile and then went back to a box end wrench, before I rounded the corners off the bolt, and luckily it came loose.      

June 21, 2001

During the last few days I've talked to a number of A/C shops to find one that can do the work on the Pantera.  Some of the shops I talked to, did not have a lift to put the car on to do the work, didn't want to work on the Pantera or they were too far away for easy access.  I decided that I would get an estimate from the Frostemp A/C shop that is nearby and I drove the car over to the shop today to get an estimate.  Needless to say, it is not possible for a shop to give an exact estimate on a car like the Pantera.   The folks at Frostemp were very helpful and we discussed the approach to getting the system upgraded.   They didn't have any problem with me replacing my own compressor and recommended that they evacuate the system before I start my work, so I would be able to remove the old compressor from the car completely to provide more access.  Frostemp has one of the machines that can evacuate the system and measure the amount removed so I will not need to pay for a complete recharge with R-12.

They looked at my existing A/C hoses and thought I should be able to reuse them.  This was good news because of pathway of the evaporator hoses on my car.  They created an estimate to include the replacement of the compressor to the condenser hose and the condenser to the receiver dryer hose, a new receiver dryer with a pressure switch and some new O ring type connectors for the hoses.  They thought it would be possible to put new ends on my two existing hoses to convert them to the new style O ring type.  We discussed different ways to hook up the pressure switch.   They recommended, just wiring it in series with the main A/C control switch but I'm thinking it would work better if the pressure switch only caused the compressor relay to dropout and left the condenser fan running.  This way the condenser fan could continue to cool down the condenser while the compressor was stopped.   As I'm installing a new compressor they talked with me about converting the system over to R-134, but I think it would be better to stay with the R-12.   I know that R-134 would work Ok, but some Pantera owners have said that it did not work as well as the R-12 because of the small size of the Pantera evaporator and condenser.  R-134 systems usually have a larger evaporator and condenser to improve the efficiency of the R-134.       

The expense so far includes the Pantera East parts as follows: 

Pantera East Parts

Item

Amount

Sanden SD-508 compressor (with R-12 fittings)

259.49

Mounting bracket

74.50

Shipping

9.14

Total

$343.13

The Frostemp estimate is as follows:

Frostemp Parts And labor

Item

Amount

Receiver dryer

$49.80

Pressure switch

$31.40

8 of #8 hose

$71.20

2 of #6 hose

$12.80

5 fittings

$49.20

Evacuate and recharge (1LB R-12)

$45.00

Subtotal Parts

$259.40

Tax

$18.16

Subtotal Parts

$277.56

Labor estimate 6.4 hours

$441.60

Total Frostemp

$719.16

Total Pantera East

$343.13

Total Estimated Cost

$1,062.29

Frostemp has estimated 6.4 hours to do the work to be on the safe side, but I'm thinking that they might be able to get it done in less time if everything goes well.   So far the projected cost of the upgrade is about $242 more than if I just replaced the stock compressor with a rebuilt unit. 

I've been running the A/C some to see if I can locate the leak that caused the oil on the condenser hose and lower corner of the condenser.  I want to make sure that the condenser is not leaking.   Frostemp said, that if the condenser leaks, it is usually very noticeable so I'm thinking it is the hose connection that was leaking and the oil ran down to the condenser.   

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The image above is a diagram of the Pantera A/C system.  Consult the Pantera service manual for more details on the system.  The above drawing does not show the A/C compressor but is connected at the part numbers 19C705 and 19972.

The following is a very simplistic explanation of how the A/C system works: 

When the system is serviced with R-12 and ready for use and the A/C control switch on the dash is turned on, the compressor clutch is engaged and condenser fan starts.  As the engine runs the compressor is turned by a drive belt on the main crank pulley and the compressor pumps the R-12 to the condenser and through the receiver dryer.  The compressor can move much more R-12 than the system needs to operate.  The compressor is controlled by a relay that is controlled by the deicing switch that cycles the compressor off if the evaporator gets too cold.  

As the R-12 is compressed in the condenser heat is released by the R-12 as  the air is moved over the outside of the condenser by the condenser fan and carries away the hot air.  The R-12 flows from the condenser to the receiver dryer. The receiver dryer has selica inside that absorbs any possible moisture in the R-12, has a filter and holds excess R-12.  The receiver dryer also has a sight glass in the top for observing the flow of the R-12.  If only a few bubbles are observed, the system R-12 level should be correct.  The R-12 is being compressed into a liquid state as it cooled in the condenser with the flow regulated by the expansion valve located at the evaporator.  The expansion valve regulates the release of the R-12 into the evaporator by sensing the temperature at the exit of the evaporator.  

As the regulated stream of R-12 enters the low pressure area of the evaporator the R-12 contacts the tubes of the evaporator and expands into a R-12 gas as it absorbs the heat on surface of  the tubes.  The R-12 is absorbing the heat inside of the evaporator.  The air moved over the outside of evaporator tubes by the blower causes the heat in the air to be absorbed by the evaporator tubes.  As the heat is removed from the air it releases some of its moisture content and condensate forms on the evaporator tubes and drips down to the bottom of the A/C/heater assembly and runs out a vent in the front of the assembly.  Air with the heat removed feels cold so we then have cold air blowing out of the A/C vents in the dash.  The downstream side of the evaporator is connected back to the suction side of the compressor where the R-12, with the absorbed heat, is pulled into the compressor, compressed and pumped back to the condenser and the cycle starts over again.   

This is a very simplistic view of how it works and does not address the details of how the system regulates its self, etc.  But it gives you the big picture of how the A/C system works and the bottom line is that the A/C system removes heat from the air passing over the evaporator and on the Pantera dumps it out in the engine bay.  A great place to put more heat!               

Stay tuned!  Over the next few weeks I'll be getting the system evacuated, installing the compressor and getting the A/C shop work done.   I will add the images of removing and installing the new compressor and the work at the A/C shop.

August 1, 2001

Over the last few weeks I reviewed my parts list with Pantera Performance to see if there were any parts that they could provide that would be less than the local A/C shop.  After the review I ordered the compressor to condenser hose that will save about $40 on the project.  I always try to support the Pantera vendors whenever  possible.    

September 14, 2001

The project has been dragging along as I collected the parts for the project.  I received the hose from Pantera Performance weeks ago and today I decided it was time to get the project underway again.   

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I drove the Pantera over to Frostemp located at 5689 Peachtree Industrial, Chamblee, GA 30341, 770-458-8585.  I needed to have the system evacuated to remove the existing refrigerant because you do not want to vent it into the atmosphere.   

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We decided to jack up one side of the car to gain access to the AC service fitting rather than put the car on the hoist.   Anytime someone is going to jack up your Pantera make sure you help them find the correct jacking points.    

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The evacuation pump was used to remove the existing refrigerant.  The amount of refrigerant was noted and I will get credit for it when we refill the system.  

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I returned home and removed the existing dryer and the short high pressure hose from the condenser.  I took the hose back to Frostemp and they made a new hose and I picked up the new dryer and the pressure switch.  The pressure switch can apparently open on a high or low pressure system condition.  It is not very visible in the last image, but the right side of the hose covering is split open from the tight 90 degree bend of the original installation.  The black sticky stuff around the dryer was apparently done at the factory to help hold the dryer in place and is not necessary and is very messy.     

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The next step was cleaning up the old dryer mounting bracket and mounting the new dryer.   I installed the new high pressure hose from the condenser but did not connect it to the dyer because I want to keep the new dryer sealed until it is time to charge the system.  I covered the hose ends with heavy plastic bags to keep them clean. Note how the new hose has a 90 degree end fitting to eliminate the sharp bend in the rubber hose.

 AC Project Cost To Date

Item

Amount

Receiver dryer (Frostemp)

$31.00

Pressure switch (Frostemp)

$19.00

Compressor/Condenser hose (PP) 

$68.70

Condenser/dryer hose (Frostemp)

$60.00

Evacuate system and make hose

$69.00

Subtotal Parts

$247.70

Tax

$3.50

Subtotal Parts and Labor

$251.20

Total Pantera East

$343.13

Total Cost (to date)

$594.33

The Frostemp hose ended up costing about $20 more than the hose I could have purchased from Pantera Performance.  See what happens when you don't support your Pantera vendors and buy both hoses!  The remaining cost should be installing new O ring hose ends on two hoses, connecting the hoses and recharging the system.  That's if, everything else on the system checks out OK!     

September 15, 2001

The plan for today was to replace the compressor to  condenser hose.

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The hose connection on the upper condenser fitting was super tight and I had to carefully heat the hose nut to get it loose.  

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The compressor fitting was very tight too and I used a floor jack on the end of the wrench to get it loose.  Image on the right shows the old hose on the left.  

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View of the completed hose installation.  I found that the lower 90 degree flare fitting on the condenser had a small smashed area on the fitting so I replaced it.  All of the flare fittings should carefully inspected for damage and then tightened very tight. 

September 16, 2001

The plan for today was to remove the old compressor and install the new compressor.

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The first step was to disconnect the battery.

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To remove the firewall, the seat belt connections are removed from both sides and the seats moved to the full forward position.  The firewall is lifted up and then pulled out.  Keep the firewall away from the weather strip.

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Next, the bolts holding the firewall hatch are removed to expose the front of the engine.  The AC compressor is visible in the last image.   

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The bolt on the top of the alternator was removed and the drive belt removed.

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The stock compressor is 35 lbs so I used a block of wood and a floor jack to support the unit.

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The four bolts were removed from the compressor mount and the tension idler loosened to remove the drive belt.  The compressor must be moved away from the engine and over the angle frame rail and then to the back to remove it.   Watch you fingers and hands, it's heavy!     

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The compressor mounting space and the view of the monster compressor.  

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I noticed that the idler pulley bearing had some play so I decided to replace it.   I just used some wood blocks and light hammer blows on a wood block to disassemble the unit.    

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The new unit is only 18 lbs so it was a little easer to handle.  It goes back in the same way the old one came out.  The new compressor has a mounting bracket that has washers to adjust the front to back position of the compressor.  I used the old compressor as a template for this adjustment by putting the new compressor on top of the old unit and then adjusted the washer positions align the two pulleys.              

September 17, 2001

The mission for today was to install the idler pulley, belts and have the system serviced with refrigerant.   

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I found a new idler bearing at NAPA auto parts, part number 6203-2RSJ.  Dick Koch helped with the part number because the number on the bearing was not fully readable.   The actual part is 6203-2RS1 but the J works fine too.  I used the old bearing to tap in the new bearing and replace the snap ring clip.  The center mounting bolt was pressed in by tightening the nut on the front side.  After installing the new bearing I noticed it also had some play, but it was a good idea to change it.  

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The next step was installing the new belts.  I used NAPA belt number 9355 for the compressor and belt number 7405 for the water pump and alternator.  I then started the car to test the belts.   I added some heat shrink tubing on the compressor clutch power wire and left the wire loose to be connected at Frostemp.  I installed only the engine hatch and headed over to Frostemp.   It turned out that they did not need access to the front of the engine.    

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Because much of the work was going to be done from under the car they put it on the lift.  Frostemp need to replace two of the existing hose ends with O ring type connectors, connect the hoses to the dryer and compressor and service the system.   The compressor and dryer are sealed when new, so I did not want to open them until all of the hose connections were ready. 

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The two old hose connections were cut off the existing compressor to evaporator and the evaporator to dryer hoses.   The hoses were in good shape and I decided to reuse them because they are routed through the rocker panel on my car.

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A special tool is used to install the new hose end.  The hose end fittings were made with a longer metal part to move the rubber part away from the headers.   The AC compressor clutch power wire was connected at this time. 

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After the compressor was connected they moved to the dryer.  A new O ring end connector was installed on the dryer to evaporator hose and a special dye was added so the system could be checked for leaks.     

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The hoses were connected to the dryer and the pressure switch installed in the dryer.  I plan to wire in the pressure switch later.   

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The R12 servicing machine was connected to the compressor service fittings and the system pumped down to 30 inches of vacuum to remove all moisture.   Any moisture boils out of the system in the very low vacuum.   The system was held at the low vacuum for 30 minutes.

Mikes AC 091701 23.jpg (87287 bytes) 

After the the system was fully vacuumed the system was charged with two lbs of R12 and lowered back down for a test run of the AC system.  

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When the car was lowed back down I started the engine (wow, ice cold air!) and all of the system was monitored to make sure it was working correctly including the condenser and expansion valve.  The AC temp control on the dash was also tested to make sure it would regulate the temp and cycle the compressor as needed.   I ran the car for about five minutes while the system was tested for operation.   Everything checked out perfectly including the efficacy of the condenser.  

The next step was checking the system for leaks.  Above, Juan Suarez uses a special black light and goggles to look for the leaks of the dye that that was added to the system before start up.   All of the connections were checked with this tool.   Next, a special R12 snifter was used to check inside the car to see if there were any leaks under the dash, compressor, dryer, condenser and all of the fittings. 

So far the system works great!   I can hardly tell when the compressor is on (completely silent) and has very little impact on the idle speed (possibly 25 to 50 RPM or so).   I can say, that the cool air is very cool deal.  

Because I started out with a working AC system the risk of finding problems with the evaporator, expansion valve, condenser, existing hoses that I reused and AC controls was low.  If you start out with a non working AC system the results could be different.   

Thanks to Pantera East for the Sanden compressor and cool mounting bracket, Pantera Performance for the hose, NAPA for the belts and bearing and great job done by the team at Frostemp; Juan Suarez, Chuck Ragsdale, David Wiley and Teri Dutton.  

 Total AC Project Cost

Item

Amount

Receiver dryer (Frostemp)

$31.00

Pressure switch (Frostemp)

$19.00

Compressor/Condenser hose (PP) 

$68.70

Condenser/dryer hose (Frostemp)

$60.00

Evacuate system and make hose

$69.00

Subtotal Parts 

$247.70

Tax

$3.50

90 degree flare elbow (Ace)

$3.07

Idler bearing (NAPA)

$9.69

AC fittings and clamps (Frostemp)

$69.00

Evac and recharge (Frostemp)

$96.60

Subtotal Parts and Labor

$429.58

Total Pantera East

$343.13

Total AC Project Cost 

$772.71

Note: I didn't count the cost of the belts as they are a normal maintenance item.

August 14, 2002

After completing my system upgrade last September the A/C seemed to function great and would provide 40 degree air at the dash vents when the ambient temp was 95 degrees or higher.  But, last week I noticed on an one-half hour drive that the A/C air at the dash vent would creep up to 55 or 60 degrees when the car was underway on the highway.  After all of the work that went into the upgrade I wanted to make sure that it was working correctly so I took the car back to Frostemp and Juan check the system.  

The system functioned perfectly at idle, there were no leaks in the system and the R12 level was fine and we had 40 degree air.  But, Juan noticed that the pressure on the low pressure side of the system slowly dropped some when the engine was ran at 1500 RPM indicating the the expansion valve was not regulating the R12 flow or the screen is plugged up some in the valve.  Another expansion valve problem indicator was that when the car was shut off the pressure in the system took too long to equalize between the low and high side.  The dreaded expansion valve problem had struck!  It was working OK last year so I strongly recommend that the valve be replaced if you are doing a upgrade.  

By not replacing the valve during the upgrade it I'm faced with a cost of $48 for the diagnostic test today and an estimated $282 (includes 2 hours labor) to evacuate the R12, install the new expansion valve, vac down the system and recharge the system with my own R12.   I have a new expansion valve on its way from Pantera Performance and will cover the installation during the next few days.   The valve is only $51!   I'm going spend some time getting the gooey A/C insulation off the expansion valve and fitting and see if I can save a little of the labor cost of the valve replacement.  It looks like it would take Frostemp at least an hour to get all of the gooey A/C insulation off the valve and fittings.

The expansion valve is located between the end of the high pressure hose and the inlet of the evaporator under the dash.  

Mikes AC 081402 1.JPG (62802 bytes)   

View of the high and low pressure hose connecting to the evaporator.   The gooey A/C insulation can be seen on the end of the hoses.  On the 71 Panteras the A/C hoses go through the passenger side rocker, up past the fuse box and to the evaporator.  Later cars have the hoses running through the center console.   

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In this view, the expansion valve can be seen covered in gooey A/C insulation after the right angle turn at the end of the high pressure hose in the foreground.

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This is a close up view of the hose connections and the gooey A/C insulation that I need to remove from the high pressure hose end and the expansion valve.  The expansion valve is on the hose at the top of the image. The small wire going into the insulation is the capillary tube from the deicing switch. 

I guess the whole world now knows that the original color of my Pantera was the very rare, exotic, 1970s and exclusive lime green

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Using latex gloves I started pulling the gooey A/C insulation off of the high pressure line and expansion valve.  I found that the insulation had to be removed from both hoses because of the fittings were so close together. 

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The round diaphragm of the expansion valve is visible in this image.  The gooey A/C insulation is super sticky and wanted to stick to the gloves.   I used a little mineral spirits on a paper towel to clean off some of the goo.    

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In this view the capillary tube coils of the expansion valve is visible and is held to the low pressure line from the evaporator with a clip.  The capillary tube from the deicing switch can be seen in front of the low pressure line.  Both the expansion valve and the deicing switch measure the evaporator temp at the exit of the evaporator.  

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A pile of gooey A/C insulation (cork wrap).

August 17, 2002

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View of the new expansion valve

August 19, 2002

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Juan hooks up the A/C controller to the Pantera A/C system. The R12 was then removed from the system so the expansion valve could be removed.

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Juan removes the expansion valve.  We removed the floor mat and put some plastic down to protect the floor if oil dripped out of the hoses.

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View of the evaporator case with the expansion valve removed.

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View of the old expansion valve with the infamous screen removed from the inlet of the valve.  I'm not sure if the screen is plugged up yet because some light can be seen through the screen.

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View of the new expansion valve installed.  The clip that holds the expansion valve capillary coil to the evaporator pipe is not in place yet.

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The cork wrap is a strip of black sticky insulation is used to insulate the evaporator pipes. 

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View of the cork wrap in place around the pipes and expansion valve.

Mikes AC 081902 8.JPG (66289 bytes)

After the valve installation was complete the system was vacuumed down, held at a low vacuum for 30 minutes and then recharged with R12.  Juan then check the high and low side pressures with the engine at idle and at 1500 RPM.  The pressures looked good and after the engine was shut off the the pressure equalized at the correct rate.  The cost was as follows:

System check out and trouble shooting  $48.00
New expansion valve $57.00
Evacuation, expansion valve replacement, recharge and test (1.5 hr) $248.10
Total valve replacement cost $353.10
Cost of original system  $772.71
Total cost of system to date  $1,125.81

Luckily they were able to evacuate and reuse my R12!     

August 20, 2002

I ran a short 20 minute test on my newly repaired A/C system today.  The sky was a partly overcast and the outside ambient air temp was 92 degrees and the humidity was 42 percent (super low for Atlanta in August).  The Pantera had been parked in the garage in the shade and the inside temp was 92 degrees.  After starting the car and turning on the A/C the A/C outlet temp was about 40 degrees within a few minutes.   When underway the hot sun was not flooding the passenger compartment like on the typical Atlanta day.  The driving was done around secondary roads with the speed not exceeding 50 MPH with both windows closed.   Within 15 minutes the inside temp of the car at the passenger seat was about 69 degrees and the A/C outlet temp varied between 40 and 44 degrees with the blower in the low position.  It looks very good so far, but I need to run a test in the hot sun.  It was cold enough inside of the car that my glasses fogged over completely when I got out of the car and within a few minutes a large puddle of condensate formed under car from the evaporator drain.

August 21, 2002

I ran an another test today in the hot sun.  The sky was a mostly clear and the outside ambient air temp was 94 degrees and the humidity was 48 percent.   The Pantera had again been parked in the garage in the shade and the inside temp was about 82 degrees.  The A/C outlet temp quickly went down to 40 degrees after a few minutes of running and the hot sun was shining into the inside of the car.  I ran the car continuously at 60 MPH and after about 5 minutes the A/C outlet air temp had slowly moved up to 49 to 50 degrees while the inside of the car stayed around 79 - 80 degrees.  

The amount of heat generated in the engine bay by the engine and A/C condenser on a hot day is incredible. When I got back to the garage I pulled out the trunk liner and the metal body parts, e.g. wheel houses, the back area of the car around the trunk liner were too hot to touch.  I expect that the system is working about a good as I can expect for the heat of Atlanta and for how hot is gets in the engine bay.  The heat is so intense I expect the the condenser is having problems releasing its heat.  The new expansion valve has improved how well the system works but it's hard to compare because the system's efficacy is impacted by the outside air temp and the hot engine bay.   I'll do some more testing when the weather cools down sometime later in the year and update this page.   

August 25, 2002

I ran an another twenty minute test today.  The sky was a mostly clear and the outside ambient air temp was 88 degrees and the humidity was 57 percent.  The sun was shining inside the car most of the time during the test.   The Pantera had again been parked in the garage in the shade and the inside temp was about 82 degrees.  The A/C outlet temp quickly went down to 40 degrees after a few minutes of running and the sun was intermittently shining into the inside of the car. I ran the car continuously at 60 MPH and the A/C outlet vent temp varied between 40 degrees and 45 degrees and the inside air temp went down to around 77 degrees.  It would appear that the engine bay temp and outside air temp is impacting the ability of the condenser to release its heat.  Overall I think the A/C is working about the best that can be expected considering the placement and size of the condenser.  The inside air temp was slowly dropping and I think on a longer drive the the air temp could go down to the 70 degree mark with the outside air at 88 degrees.  After all this work and expense I'm glad I stayed with the R12 because the Pantera A/C system needs all the help it can get and the improved efficiency of the R12 over R134 helps. 

August 28, 2002

The early cars (before #1910 or so) had fresh air supplied to the A/C/Heater box from an elongated vent if front of the windshield under the grill work (the opening is toward the center of the car).  On these cars the top A/C control lever is marked AIR OFF.  Im lucky to be the owner of #1887 that also has the pull for fresh air knob option that directs conditioned air at your legs. The really odd thing about the fresh air intakes is that they are down stream of the blower fan?  Because the outside air enters from the top front of the box, it looks like some of the air could even be flowing in down stream of the evaporator.  I ran a test on the air flow.  With the AIR Off lever in the AIR position, the blower motor on, the car at rest and found that a lot of air is blowing OUT of the outside air vent.  It must be blowing some of my cold A/C air out of the car at rest and getting hot outside air pushed in at speed when the air pressure is high at the air intake.  I think I just found the cause of why my A/C vent air temp is warmer at speed!  It just might be that I need to close off the outside air.  I'll do some more testing later.

August 29, 2002

I did some more testing and it looks like closing the outside air control solves the A/C air temp problem.  With the outside ambient air temp at 92 degrees, the A/C outlet temp stays at 39 to 40 degrees and does not change with the speed of the car.  This hot air bypass problem will only happen with the early cars that have the outside air intake on top of the A/C box.  The later cars (in the 1974 time frame) that have an outside air control, pick up the air, up stream from the blower.  Another de Tomaso Pantera puzzle solved!

July 23, 2009

A couple of years ago I noticed what looked like refrigerant oil on the bottom back of the compressor and there were a lot of bubbles in the sight glass.  I quit using the system, but today I decided to tackle the apparent leak.  I took the car to Sims Radiator in Atlanta because they have good reputation for A/C work and had Freeze-12 to recharge the system.   

They are located at:

5580 New Peachtree Road
Chamblee, GA 30341
Phone: (770) 451-2004
Hours: M-F 8:00-5:30 Sat. 10:00-2:00          

The system already had leak detection dye and they quickly found that one of the service fittings was leaking at its seal where it threads into the compressor.   They replaced the O ring on the fitting and vacuumed the system down, tested it for leaks and it was OK.  They added two ounces of oil to make up for oil that was lost with the leak and charged the system.  The Freeze-12 seems to work great and I'm getting about the same outlet temp that I had with R12.