Cab1

I have a 74 with a fresh short block 350, dual exhausts with long tube headers and a 3/4 race 400 turbo. Nothing fancy, but it can get out of it's own way nicely - which is better than most stock 74 owner can say. Anyway, a few years back I had the stock A/C rebuilt from the ground up. Boy, what a mistake! The day I drove it home from the shop with the A/C blowing I was shocked at how bad of a performance hit I got. That A/C unit just sucked the life right out of the car. What was once a snappy no nonsense wheel turning little bad boy had become a dog. I wanted to puke. Look, I know A/C is a power drag, but this is just beyond the tolerance of any serous motorhead. So what's the deal here? There are a lot of cars out there blasting down the road with their hair on fire, the radio roaring and the A/C cranked up to arctic levels that would frost over your RayBans. Is it because the stock A/C system is so inefficient? Do I have to rip it out and go with an aftermarket box? What's the fix here?

Mark Riles

Sounds like something could be wrong with the compressor. That's where I would start. There are other options as well. You can always convert to a newer more modern style compressor and upgrade the system as such. It'll be more efficient and in many cases even cooler.

anips

its the nature of the beast, now that you got a new one its drawing down power and should be delivering lots of cold air, i'll be going down the road 65-70 turn the AC on and the car slows down and on a real hot day the temp gauage goes up, keep an eye out for oil being thrown from the clutch to the under side of the hood thats more of the bad nature of the beast even with a new compressor, changed the seal twice still does it, so i disabled the AC and drive around with the windows down, someday I get around to changing it out for a late model set up.

7t9l82

the compressor on that year and others like sucked a bit of power but something may be wrong with it. the new compressors are much more efficient.

Manuel Azevedo

Assuming there is nothing wrong with your compressor, going to something like a Sanden will help alot, also an override to cut out the compressor at WOT works really well also.

great68

Cab1, I know what your talking about!!!! I have a 68 427 with a/c and when I turn on the a/c the front end noses over and my a/c is new. I wondered what was wrong with it too!! I have had bb's with a/c and this does'nt seem normal. I too need help..

pauldana

you have ether to much oil or to much gas or both in the system...

for me it was to much oil.... this will fix it

Cab1

I feel your pain, great68. It's especially horrifying when you have a stout big block under the hood. This should not even be a remote issue for you. Something is definitely wrong. Adding insult to injury, the A/C barely cools the car - even with it cranked up full blast. I don't know about you, but driving this beast around without A/C is not an option. It will fry you alive. Anyway, there's some real wisdom here - starting with the compressor. It's a boat anchor. Maybe going to a newer model would help. Then the gas and oil levels might be off - but that should have been addressed by the installer. This is a new system. So maybe that's the problem, the guy didn't know what he was doing. Finding the right A/C guy who knows what he's doing is probably a better way to go then beating on it with a rock.

noonie

The results of poor output and excessive drag are consistent with an improperly charged system. You may in addition have a bad compressor.
The A6 was in a gazillion GM and other brand vehicles and remains today as probably the best compressor ever made. It will put a drag on power, but not to an unacceptable degree. After all it's powerfull enough to cool a small house.

You can go to a more modern compressor that seems more efficient because they displace less and require less power and along with a much more efficient modern condenser, you should gain what you are after.

great68

Wow that's great I'll have this checked out!!! Thanks so much for the info I hope this is the case it's a new compressor. It's impossible to drive a car in Texas without A/C, even in the winter!!! Soon as I find the problem I will let everyone know. Again thanks to all.

briankeery

Ken...for some reason I can't send you a PM.....the ebay part # for your car cover is 180655852708....hope this helps....sorry about hijacking the thread guys.

Brian