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Topic: Installing A/C on my 75 Vette

Installing A/C on my 75 Vette (1/4)
 2/8/20 3:34pm
BillHanna
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Cana, VA - USA

Vette(s):
1975 Stingray 71 350 engine Flat top pistons Sniper fuel injection Hyperspark ignition


Joined: 7/3/2016
Posts: 187

When I bought my 75 Vette, someone had stripped the original A/C, leaving only the evaporator in place. I also never get enough heat from the heater, so I ordered a Vintage Air unit for my car. This gets great reviews for ease of installation and great cooling. It also includes a heater as part of the system. I had thought about having someone install this for me since I don’t relish crawling under the dash, but looking at their instructions made it look doable for me. By this point I have had almost every part of the dash apart anyway, so I didn’t expect any surprises.

The system comes in three boxes; compressor, evaporator assembly, and condenser and related components. The instruction manual is 30 pages and is very detailed. After reading it completely, I can see that the dash must be removed completely, and some drilling and cutting is required.

I pulled the right side dash and center console, then went under the hood to pull the evaporator housing. I first had to remove some of the fuel-injection wires that I had recently installed with the TBEFI in order to get to the housing. I removed the coolant overflow tank (two bolts accessed from under the fender), and then removed the evaporator bolts and removed the housing.

Next I went inside to remove the heater assembly. Getting the heater hoses off was a pain since they were under the car, up in a bit of a recess, old and stuck fast to the heater tubes. To free these I sliced along the hose at the heater tubes, then twisted, pried, and cried a bit until they finally let go. Once the hoses were out, I could roll the heater box down to disengage the heater tubs from the firewall. In order to get room to move the heater box out, I had to remove the driver’s side gauge cluster, which had to be done eventually anyway.

Once the heater assembly was out I removed the blower assembly from under the hood. The sealer they used between the blower and the firewall was still tacky and stretchy after all these years.

The next steps were to remove the heater control from the center console and all the related vacuum hoses and wiring. Then I disassembled the control to convert it to the new heater/AC setup. Converting it required disassembling it to replace the plastic piece that shows the functions and adding electronic controls in place of the existing cables and vacuum controls. To replace this lens required grinding off tabs that held the assembly in place and temporarily removing the existing control wheels. When I tried to put the wheels back in place, they did not go down low enough to engage the hubs that move the dials. I had to break off the retaining tabs on the base again, lift the assembly a bit, put the wheels in place and then put it all back together again. I wish the instructions had provided a bit of insight to this issue.

The next step was to replace the vents with adapters that work with the new system. The on/off controls for the vents were also removed since the new electronic system provides this function at the control panel. Then the firewall needed to have mounting holes drilled, and the cutout expanded for the heater/AC lines. Fortunately, the firewall is fiberglass so it was easily cut with a saber-saw and die-grinder.

Then I added the brackets to the evaporator, and installed the tubing for the AC and heater on the evaporator housing. When the instructions say there may be pressure built up, they are right! I removed the screw-on caps off of the heater core, and there was a plug in the tubing. A few minutes after the caps were off, one of the plugs blew out with a bang!

I mounted the brackets onto the engine for the compressor, which required moving heater lines, fuel lines, and the ignition box that I had mounted above the suspension beside the right fender.

I thought mounting the condenser would be the easy part, but where there were supposed to be factory lower mounting bolts in the core support, there were none. There was not enough room to drill and tap holes, so I ended up using a small “C” clamp to hold the bottom. If I ever pull the core support again, I’ll drill the proper holes. Next I started to install the hoses to the compressor, condenser, and evaporator, but one hose was too short, and another was too long. A call to Vintage Air and they sent parts (at no charge) to make new hoses. Then the two heater hoses with the heater valve were installed.

Then it’s into the car to install the 3 dash panels with all the associated wiring and vent hoses. The vent hose came in one six foot section that needed to be cut to the specific lengths.

Getting the dash panels back in place was a challenge. The center console and gauge cluster just wouldn’t fit with the new vent hoses in place, so I removed the ducts and installed the cluster without the ducts.

After filling the radiator, one of the heater hoses was leaking at the firewall. While removing the hose, the tubing to the back of the heater was loose. I had to remove the heater/AC evaporator unit from the inside and tighten the heater fittings. I thought sure I had gotten both quite tight. Quite a discouraging day, but at the end of it I had both the center gauge cluster and the heater in place. I have no idea why the heater hose was leaking, but I cut off the end of the hose and reconnected it. Tomorrow I just need to put the steering shaft back together (this was taken off to drop the steering column and get the driver’s side gauge cluster out), add the shifter boot assembly, and re-install the electronic ignition. Once the new hoses to the air-conditioner system arrived, I measured them and brought them to the local NAPA parts store to get them cut and crimped.

After everything was complete, I started the car and it overheated! It would not take the last gallon of antifreeze so there was an air pocket in it. I’ve never had that happen on a small block Chevy before. The next day the water had settled, and I was able to add the rest of the antifreeze, then the engine ran normally.

One of the heater hoses still leaked where it goes into the firewall. I removed them and could see nothing wrong. After re-installing them I pressure-checked them and they did not leak. But after taking a short ride, and after the engine cooled down, it leaked again. I’ll have my mechanic check this when he charges the AC unit.

The heater fan switch had no effect, so I contacted the vendor and they said that it happens when there is a bad ground, but I checked all the grounds, and they were tight. More frustration! Vintage Air then asked for the ECU (computer) number on the unit, and after looking it, it looks like it was shipped with the wrong ECU! Vintage Air sent a new one right out. This is mounted on top of the evaporator housing, which is tight against the inside of the dash. Not easy to get out and back in.

Now that the system is fully installed and working, I took it to my mechanic to get it charged. While driving, I could smell rubber burning. I found the rubber flap that goes over the steering suspension was caught in the A/C belt and was rubbing. The belt goes right beside the suspension so I just moved the flap out of the way.

The original heater in this car never put out much heat, this unit is much better. We’ll see this summer how the air-conditioner does.



The instructions were clear, but not as complete as I would have liked. In many instances they say “remove” when it would have been helpful if they provided some instruction on how to remove it. For instance, on the heater control panel, you have to remove part of the assembly to replace the display panel, which is a piece of plastic with the labels on it. But the assembly is held in place by peening over the lips of the casting. But what is the best way to get the tabs out of the way so the assembly can be taken apart? I couldn’t get enough of a grip with pliers to bend them, so I ended up using a Dremel tool to grind the tabs back. I’m sure there must have been a better way to accomplish this. At one point, the instructions said to cut out a piece of the plastic backing on the right dash, but I have no idea why.

This is a quality unit, and contained everything needed to complete the job. When I had questions, the staff at Vintage Air were responsive and thorough in their answers. There were times I wished I had just paid someone to do this, but once it was all done, I was satisfied and knew I had saved a pile of money doing it myself.







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Re: Installing A/C on my 75 Vette (2/4)
 2/9/20 2:38pm
NorskyLifetime Member
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Twin Lakes, CO - USA

Vette(s):
SOLD - "The Toy" - 1970 Convertible
SOLD - "The Beast" - 1990 ZR-1 (#682)
"BLKBRRD" - 1978 Trans Am, 400ci/225hp, 4 spd, Black w/black interior, Hurst t-tops


Joined: 1/23/2002
Posts: 6871

Great write-up Bill.  Nice to know that there are outfits out there who do a better than average job on their instructions AND have knowledgeable folks on the Help Line to get one through problems.



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Jim Olson 

"The Toys"...!!!  Save the Wave!

Where I've been in a Corvette...!!!

Re: Installing A/C on my 75 Vette (3/4)
 2/10/20 2:33am
73shark
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Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.


Joined: 7/9/2003
Posts: 607

That sounds like a lot of work. Seems like a lot more than when I put factory air in mine about a year after I got it. I realized after about a year that not ordering it with factory air was a big mistake. I salvaged all of the parts out of a wrecked 73. However, I didn't have to remove the driver side instrument cluster for the factory air. Probably because the ductwork was on the bottom of everything.

Surprised since yours had factory air originally that there weren't holes for the condenser.

Great writeup.



|UPDATED|2/9/2020 11:33:01 PM (AZT)|/UPDATED|


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1973 L-82 4 spd

Re: Installing A/C on my 75 Vette (4/4)
 2/10/20 10:58am
BillHanna
Standard Member
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Cana, VA - USA

Vette(s):
1975 Stingray 71 350 engine Flat top pistons Sniper fuel injection Hyperspark ignition


Joined: 7/3/2016
Posts: 187

73shark said:

That sounds like a lot of work. Seems like a lot more than when I put factory air in mine about a year after I got it. I realized after about a year that not ordering it with factory air was a big mistake. I salvaged all of the parts out of a wrecked 73. However, I didn't have to remove the driver side instrument cluster for the factory air. Probably because the ductwork was on the bottom of everything.

Surprised since yours had factory air originally that there weren't holes for the condenser.

Great writeup.



A big part of this install was removing the factory air system.  Overall, I put about 50 hours into this project -- which seems quite a bit to me.  I read one post that someone paid over two-thousand dollars to have his installed, so maybe my time was not that far off.  Doing a similar job a second time would surely take a lot less time, knowing what steps to take ahead of time.

The only thing I can think of why there were no holes in the bottom for the condenser is that someone must have replaced the core support at some time.


 



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