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Installing
an original Dealer Air Unit on a TR6
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| So you're
tired of the hot summer days in the old TR6? So was I. I drive my
car on a daily basis and it does get hot and humid here in North Alabama.
The solution was installing an a/c on the yellow beast. I looked at many options, including an aftermarket kit but settled on an original Dealer a/c kit. The main reason for choosing an original kit was it was readily available. We have a local British car guru who had 2 units that had been pulled from TR6's. If I would install one of the a/c units on his Carmine car and get it working, I could have the remaining unit for my Mimosa Yellow car. I obtained a copy of the original installation manual sent by a member of the TR6 email list (thanks Brian Z!). I've looked at several installations and found they all had minor differences, even on cars known to be original. This was a dealer installed item and I think they used the installation manual as general guide line and installed them to their own tastes. You will notice differences in line and wiring routing on most cars. It took two weeks of evenings and Saturdays to install the system on the Carmine car. At the owner's request, I took a minimalist approach to this installation and did not convert to R-134a, instead opting to use an R-12 substitue called "Freeze 12". By doing this I was able to keep all of the original components and didn't have to worry about removing the old oil from the system. The only items replaced on the Carmine car were the refrigerant lines, the electric cooling fan and some faulty relays. All parts were sourced locally as the refrigerant lines were made up by a local hose shop. This conversion works well and it's a good way to do this job without doing a tremendous amount of work and going through a lot of expense. A word of advice, make sure your kit is complete. The pulley shown in the picture below is often missing. This pulley actually replaces the metal fan hub and it is a very specialized part that cannot be purchased new. 
I approached this job in these steps: 1) Clean up and evaluate the condition of all components. 2) Acquire replacements parts as needed. 3) Install the compressor brackets. Re-route fuel lines, heater hoses and vacuum lines as needed. Trial fit the compressor to check clearances. Remove the radiator and install the front pulley. Re-install radiator. 4) Cut the necessary holes in the firewall and trial fit the evaporator section and the refrigerant lines under the dash to ensure the holes cut will work. 5) Install the condensor and associated brackets. Cut the existing fan shroud so that it will fit over the condensor and refrigerant lines. Connect all refrigerant lines and pull a vacuum. 6) Determine routing of wiring and correct any electrical issues 7) Charge the system with R-134a and road test. The first step was to clean up the unit. After years of storage in a barn, quit a bit of "crud" needed to be cleaned.  Evaporator section (top view)  Evaporator section (side view) After the clean up I started securing new parts. The original compressor showed signs of leakage around the front seal so a rebuilt unit was purchased. The clutch had a bad bearing so that was purchased as well. I took measurements of the old lines and had news ones made at a local hose shop. I wanted to convert this unit to 134a so a new expansion valve was installed. The relays were also shot (on both the Carmine car and my car) so new relays were acquired. The original style relays are NLA so I used inexpensive relays sourced locally. 
Now that all needed parts have been acquired, it's time to install the compressor bracket and front pulley. I had to re-route the fuel line and the heater return line to get the bracket installed. I also used some insulated clamps to clamp the heater hose to the compressor bracket to prevent the bracket from wearing a hole in the hose. This has not been done on several other installations I've seen and there was evidence of the hose being damage on these installations. To install the front pulley, remove the radiator, install the pulley (replaces the fan spacer), re-install radiator. We are now ready to cut the needed holes in the firewall to allow the exit of the wiring and refrigerant lines. We also need to cut the large hole allow the blower motor clearance under the dash. All dimensions and measurements are provided in the installation manual. After the holes were cut I trial fitted the a/c evaporator section to ensure all holes would line up. No alignment problems were encountered since the installation manual had provided accurate measurements. The next job is to install the condensor. This is where things get interesting as my Mimosa car has an oil cooler. The Carmine car did not have an oil cooler so the job was not as tight and the electric fan would fit. On my Mimosa car, the electric cooling fan would not fit in front of the condensor. After running the Carmine car, I found the fan did not appear to be needed using the "Freeze 12" product as the head pressure never got high enough to bring the fan on. The question of the day: Would this also be true for R-134a?  View of condensor mounting from right side. Note the lines were attached to the condensor just before it was installed. Installation of the condensor involves trial fitting the complete condensor (refrigerant lines and all) and then trimming the radiator shroud to fit the condensor. After you are happy with the fit you can go ahead and mount the condensor and radiator shroud. It took me two or three tries on the radiator shroud as I was trying to cut the minimum amount of material to prevent air leakage. If the air is leaking from the shroud in huge quantities then it is not being forced through the condensor and radiator at road speeds.  After completing the condensor installation, the next step is to install the evaporator section. Make sure you wrap the connections with foam tape or the a/c will sweat and drip water on the floor of your car.  Evaporator before installation, note the foam tape wrapping the fitting to prevent sweating. You also need to wrap the expansion valve to prevent sweating. This picture was taken with the evaporator upside down from the side. I connected the remaining refrigerant lines, installed the filter drier, and then pulled a vacuum. You need to leave the filter sealed until you're ready to pull a vacuum or the filter will absorb moisture from the atmosphere. |
*click on any image for a larger
image*
Original compressor and mounting brackets 
New suction line, notice the hose shop had to braze a new barbed end so the original fitting could be used  New 134a expansion valve  Compressor mounting (side view)  Compressor mounting (front view)  Compressor mounting (top view)  Side view of completed compressor mounting  The holes for the refrigerant lines are cut, the rear hose is the large suction line, the front hose is the smaller liquid line  The hole for the blower has been cut. I used hole saws to cut all holes and then primed and painted the raw metal to prevent rust. Notice the rubber grommets have been installed for the refrigerant lines.  View of condensor installation from left side. The lines you see clamped to the inner fender and entering the radiator shroud are for the oil cooler.  View of the refrigerant line routing on the compressor. Note the clamps with the rubber insulators to prevent damage.  View of left bulkhead details. Note the filter drier mounting.  Evaporator before installation |
View of the engine bay with all components installed Next we need to sort out the wiring. In the installation manual was a real gem, a complete wiring diagram. I simplified the wiring somewhat because I didn't use the condensor fan, which eliminiated one fan motor, one relay and one pressure switch. I was left with a single relay that is used to apply power to the system when the ignition switch is in the "on" position. |
 I used some foam tape on the filter drier to keep it from scrubbing the paint. This is the same foam tape used to wrap the lines at the evaporator to prevent sweating inside the car. |
 Only one relay was needed in my application since I didn't use the condensor fan |
 I pulled the power for the system from the positive battery block. I found some wide terminals that allowed me to do this. Note the fuse protecton. |
 Driver's side vents and controls |
 Driver's side vent and controls |
 Passenger's side vents |
 View of blower and expansion valve (Passenger's side) |
| Now that the
wiring is completed, it's time to add the oil and charge the system.
I used a synthetic Esther based oil. The system holds about 15oz of
oil when completley empty. I added 1lb and 1 oz of R-134a to the system.
This is the point the sight glass cleared up and the discharge air
temperature was good and cold. Always charge the a/c with the blower
on "high" and the engine running about 2000 rpm to prevent
overcharging. I've been driving the car all summer and it has been
cooling quite well with no signs of overheating. On an 85 degree day
with the fan speed on low I can get discharge temperature of 35 degrees.
Not bad for an a/c unit built in 1975! If you find an error in the article or need further clarification, please email me at tgeiger@aitinc.com |
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