New Feedback on '85 Vette

[nmacdonald]

Today was my first chance to actually put some real miles on the car - right at 200 and most of it highway miles with a full tank of fuel and a bottle of Chevron Techron fuel system cleaner.

Here are two things I noticed while on the drive:

1) The AC does not blow cold air. The dealer supposedly checked it before delivery, but I suspect that all they did was add freon. I did notice one time for about 20 seconds, ice cold air out of the vents, then it stopped. I suspect something different than freon. Any thoughts.

2) The drivers side window sounds like it's about to fall out on bumpy roads. All the way down, no problem, all the way up, no problem. But partially down and it rattles like crazy, especially near the door handle. Any thoughts.

Before I call the dealer to discuss the issues, I thought I'd troll the knowledgebase here and see what I came up with.

Thanks in advance....

 

[tyrel]

I'll do the easy one first. The window rattle thingy is common on the C4. The first time I closed my door with the window halfway down, it sounded like an elephant falling down a stairway. All the way up, no problem, all the way down, no problem. The c4 hates halfway opened windows, and it's quite normal.

As for the a/c, this is something you could possibly diagnose yourself, here is an excellent forum dedicated to the a/c DIYer if you're so inclined:

http://www.aircondition.com/wwwboard/

I suspect that after many years, if you have the original refrigerant R12, the system is simply leaking from age as all a/c systems are so inclined. If you do not have a label on the compressor stating that it has been retrofitted to R134a, and the service fittings have not been changed, then I highly suspect you have the original refrigerant, and twenty years is a lot to expect out of a car's a/c. The weak point is always the shaft seal on the compressor, although you could also have leaks at the condenser or the evaporator. I have a friend who is an ASE mechanic, and in twenty years of working on cars, he has never seen an a/c o-ring failure (a/c o-rings are used in areas where the hoses are joined to components). The hoses will leak before the o-rings, they are tough monkeys. But I highly doubt you need new hoses.

Here is a site that shows you a repair and a retrofit for your style of compressor:

http://www.diynet.com/diy/ab_auto_air_conditioning/article/0,2021,DIY_13674_2276708,00.html

At the very least you will need a new accumulator, and possibly a new compressor. A new condenser wouldn't hurt, I picked up one on Ebay. A/C work is always expensive, you're probably looking at a $1,000 repair bill with parts and labor, and keep your fingers crossed that the evaporator is intact. Your mechanic will probably use dye and and also an electronic sniffer to find the leaks, but again I highly suspect that it's leaking from the shaft seal on the compressor. Shaft seals can be replaced, but for warranty reasons most mechanics will prefer to install a new or remanufactured compressor, along with a new compressor clutch. The compressor/clutch combination is one of the most expensive parts on your car.

So to sum up, your mechanic will probably check the high- and low-side pressures using manifold pressure gauges, and my hunch is that the readings will be way below spec. He'll also probably use a sniffer to look for leaks. He'll evacuate the system, flush the oil out of the parts he's going to keep (evaporator, condenser, the lines), install new accumulator and compressor, change the o-rings to R134a compatible o-rings, put in PAG oil, pull a vacuum, and recharge with R134a. Then he'll monitor the high and low side pressures and read the temps at the vent (even with R134a you should get to 50 degrees). It's a big job, and many little things can go wrong, that's why it costs so much.

Good luck!

 

[nmacdonald]

Tyrel...

Thanks for such a thorough reply. I did notice yesterday, while doing some probing, that the AC compressor pully was spinning then engaged. Once that happened cold air aplenty. I tried to get it to repeat that, but the ac stayed cold and consistent for the remainder of the time. I'm going to check again today. Guess it could be as simple as a loose belt perhaps. (fingers crossed)

Too bad on the window thing. But thanks for the heads up on that one.

Much appreciated.

 

[Daryllawman]

Hello and welcome to the Corvette Action Center...Enjoy!!

 

[G Winter]

The system is equiped with a pressure switch on the low side of the system. If presure gets to low it shuts off the compressor to keep it from buning itself up . You will notice in warmer conditions it my start for a min. and stop . Cooler condititons it may not run at all. That is an indication of low freon .