First I want to say thanks for all of the help I always receive on this forum.

My son and I are in the process of restoring his first car a 1974. Btw he pays for a lot of this with mowing lawns and dog sitting, great kid. Anyway, we are buying parts and restoring it piece by piece and need to address the AC system. We live in Dallas Texas and summers are brutal. Here's my question (or questions). The AC does not work at all. I have read some posts on here and was wondering if it's possible to totally rebuild his AC system and it will actually blow cold air or should I just do a vintage air?

- I realize vintage air makes a great product but they look pretty expensive and somewhat challenging to install but I would be willing to do it if it will keep that cabin cool and if I can do it in my garage where we are building the car.

OR

- Can I just upgrade the original system, new compressor, components, etc and have it work well.

Any thoughts on one vs the other. We are on a budget and need to make sure it's something we can do. It seems to me it would be easier to replace factory components with upgraded parts that are bolt on instead of trying to put in an aftermarket system but I would love someone else's thoughts and feedback.

Thanks everyone in advance

 

I purchased a copy of Air Conditioning Strategies for the 63-82 Corvette by Michael J Davis, published by Prestige Publishing. By using his simple and reversible methods I had 41* air coming out of the vents of my 79 on a 98* day here in Southeastern NC with a stock GM AC same as came with the car. You've probably had the AC shop test your system and tell you your car AC is fine and should be cooling great but you're still sweating. The problem is not the AC, you paid someone to check it. The problem is the car.
Find a copy of that book and it will explain every modification. It will also explain the theory behind every suggestion. Believe me, the problem is really the car, not a crappy AC.
Good luck.

 

Well, there's a lot of "meat" here to chew on....


If your A/C system is still intact (even though it doesn't work), there's a pretty good chance that you can repair it without having to replace all the 'important' parts. IF [a very important word, here] there is no damage to the evaporator core or the condenser components, you can purchase a conversion kit to R-134a refrigerant. That includes a new Senden compressor, main hoses, swap-out/repair/recalibration of your existing POA valve, brackets and misc. hardware/switches. You retain MOST of your system and replace the [normally] troublesome pieces.

What's involved? Opening the system; removing compressor, POA valve, and drier; flushing out the old components and lines that will remain ($15 spray can A/C flush/cleaner from parts store); blowing out the cleaned system to remove any residue/cleaner; buttoning it all back up; and taking it to a shop that can vacuum the system down and charge it with R-134a.

Now, if the system had a mechanical failure that could have contaminated everything, this option is not the way to go....until the problem is identified and the system cleaned out so debris is eliminated.

It is also possible to just repair the system back to stock state. It would be best to take it to a pro to diagnose what is wrong with it and give you an estimate for repairing it.

 

Why spend money on parts you may not need?. Before making decisions on what to do with the AC system, determine what you have to start with.

If the car is drivable, take it to an automotive AC shop and let the pros evaluate the system as is.

 

I'll be following this closely... I'm in the exact same boat with my '76. Everything is there, the blower works (somewhat), but no cold air. It's not high on my list of priorities right now, but it IS on my two-year plan.


Please keep us updated!

 

In a nut shell, yes.

I just replaced my compressor, orifice tube, pressure switch, and accumulator. Probably $450.

Sucked it down with a $100 vacuum pump, left it overnight and it held.

Jambed in 3 lbs of R-12 and 6? ounces of oil. $100. Chills great.

You NEED to know the condensor is clean. If a compressor blew its cookies , the parts end up there. If you suck in any metal later from there, game over.

If you switch to 134A, it gets more complicated.

 

Unfortunately, the O.P. has a 74, with an A6 compressor and a VIR, not an R4 and a modern orifice system. It makes a world of difference. (I'm sure that someone will post their experience disputing this.) If you are going to keep a GM HVAC, the best starting place is with a late 77 thru 82 system. (This is the same basic system used by GM for all Corvettes thru 2017) These C3 systems can be retro-fitted to any C3 and will give you the performance described above.

FYI, I have an early 77 which had the VIR system. I replaced it with a Vintage Air - I did it alone in my garage (though I had to make a number of custom parts to adapt the VA kit to a 77 - VA kits only go through 76. I believe that this is significant as GM began using the orifice system in mid 77)

 

The only disagreement I would have , is the A-6 is better than the R-4.
They are bullet proof. I bet I have 4 used R-4s on the shelf. They are noisy and just don't last.

 

Steve

I too am about to tilt at this particular windmill.
My 69 has factory a/c that the previous owner (since 1978) claims to have not used since he owned her (and I believe him, only 10,000 miles since 1978!)
I pulled a vacuum on system and it would not hold soooooo my first plan of attack is to replace all rubber hoses and all o rings that I can get to without removing the hood. Then I will try pulling vacuum and see what happens. Zip corvette has the pre-made hoses for $250 total. I did try the compressor. No bad noises and the clutch does engage!
I am determined to keep R12 and factory system.
VERYSOON

 

See if you can find the leak first. believe it or not, those original hoses are killer, and rarely the issue. Bad o rings, bad schrader valves, and compressor front seal are where I would start.

 

The hoses do look great! Car was stored most of its life in a controlled climate garage!!
Would the zip o-ring kit cover all the O-rings needed?
Thanks
VS

 

I just buy assortment from NAPA or any parts store.
Coat them in oil, install, use air to pump it up to 100lbs and get a brush with dishwashing soap.
You'll find the leaks.
Just be patient. It's just not that hard.

 

The front seal on the old compressors is the normal point of leakage. And, the less use the system gets, the more likely it is to leak.

I just couldn't stay with the old R-4 compressor any more: noisy, heavy, inefficient (by today's standards). So I opted for a Senden compressor and pressure switches (rather than the POA valve).

If your budget is tight, get the original stuff fixed--unless the compressor threw craps... For low dollars, a pro can find out what's wrong with your system and give you a repair estimate. R-12 refrigerant is a LOT more money than R134a; that should be considered when making your decision on which way to go.

 

I agree that the R4 is JUNK. My 85 Jaguar conversion (sbc, tpi & 700R4) is currently waiting replacement of its R-4 for a Sanden.

 

I want to thank everyone, I've decided to just go ahead and get the vintage air system from Ecklers's. Looks like it has everything and should work great. Someone mentioned Mike Davis's AC book, he's actually a very good friend of mine and recommends the VA system as well. I'll get it on the way. As always thanks again.

 

Mike's book is no longer in print. Has he looked into making it available through one of the print on demand services? Seems like people are regularly referring to it. I just bought one off ebay and found some interesting stuff in there.

 

What part of Dallas? I'm in McKinney. I'm just finishing up a VA install in my 69. I don't have it charged yet but it blows very hard. I just need to get the dash and console put back together. I can't wait.

 

Steve
Here we go with A6 reseal. Took out receiver/drier no problem from the bottom. Orings were perfect and oiled. Replaced Schrader valves and lubed with Nylog. Vacuum held perfect for twenty minutes. Pretty sure leak down is from old compressor shaft seal. 1.5 ounces oil in receiver. A little cloudy. New receiver on the way. Don't give up yet. I'll keep you informed or anyone else that cares. R12 all the way!!
VS

 

I agree with this post completely. The A6 is bullet proof and after rebuilding about 70 vette compressor, I have never had one that came in that spit out parts. There is nothing that can go thru or fit thru the high pressure port. If the compressor fails, the failure would cause a lack of pressure and the high pressure would flow the opposite direction towards the low pressure and enter the compressor. Crap can't get out backward thru the inlet filter.
I also think that the advice to see what you have to deal with is the best.
The main cause of A6 failure is the mineral oil. I allows things inside to rust. The rust crawls under the shaft O-ring and causes a leak. The ceramic can actually be used over again with new O-rings. it's O-ring failure that causes the leaks, and the O-rings are stationary. They do not spin on anything, they are only there to seal both parts of the ceramic.

Dom

 

Well I spent the day removing and resealing my A6 compressor. It looks bulletproof for sure. Hardest part was putting the clutch hub back on. (Take woodruff key out and align for installer!). I used the new type shaft seal. SOB is tight!! Put 8 ounces of oil in and letting stand overnight to see if any problems with seal at front of compressor case. Will hook it back up and do a vacuum test and see how it does mañana. Touch of vodka just now.