85 vette ac issues
Thread Starter
Heel & Toe
Joined: Jun 2013
Posts: 17
Likes: 0
85 vette ac issues
I have an 84 vette the ac has been converted 134a few years ago, the compressor has been replaced at the same time, now about 7 yrs later I had to replace the Schrader valve, because it was bent and would take refrig, So now to the issue, I refilled with 134a 2.75lbs as stated on the bower. I start the car turn on the ac it cools down to about 38 to 40 degrees for as long has the car is running, great, Now when I turn the car off after about 30 miles and wait about an hour or less and start the car and turn the ac on I get warm ac some time but not all the time I can get cold air but then it goes warm again any ideas, summer is here and it has a glass top. Thanks for any help.
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 42
From: Baltimore, MD USA
The 2.75 lbs of refrigerant is for R12.
If you have R134a you should charge the system to around 85%
of the R12 which is 2.3 lbs.
Could also be you have a refrigerant leak. Only way to verify
is attach some manifold gauges and verify the pressures.
If you have R134a you should charge the system to around 85%
of the R12 which is 2.3 lbs.
Could also be you have a refrigerant leak. Only way to verify
is attach some manifold gauges and verify the pressures.
Pro
Joined: Oct 2012
Posts: 648
Likes: 6
From: weems va
I went through same thing with my 93.
Thread Starter
Heel & Toe
Joined: Jun 2013
Posts: 17
Likes: 0
ok, I found out it was over charged, now psi is about 30 to 40 lb. But I seem to have the same issue, took the car out for about a 20 mile ride and the ac worked just fine, the car sat over night, went to go out the next after noon truned on the ac took off it was cooling then about 5 minutes it stoped cooling, any ideas?????????? is there a wireing diagram for c4 ac's? sound like it could be a clutch issue??
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
You need to see if the compressor is running and I'd guess that it isn't; and the most likely thing keeping it from running is the Low Pressure Switch. Verify at least 50 psi static pressure (nothing running) with your gage set and then use a DVM to see if the Switch Contacts are closed. If not, get a new Switch. If so, jumper the Connector plug with a paperclip which should fire it up. Then hold the Connector on the Switch and/or wriggle it around and if it runs you can try to tighten up the Connector contacts with some needle nose pliers; replace the Connector altogether; or simply try another Switch (which on the later Years seems to work without having to do anything else when this situation pops up).
Burning Brakes
Joined: Apr 2011
Posts: 917
Likes: 25
From: College Station Tx
Sounds like an issue I had on a Volvo. Over time, the gap between the clutch plate and pulley gradually increases. When the gap gets too big, the clutch will not be able to engage. So, when you first start the engine in the morning, everything works fine. As the compressor heats up and the gap increases, the clutch no longer engages...hot air. Give it 10-30 minutes to cool down and everything works well again. I know this isn't a Volvo, but the same thing might be happening since I believe the corvette also has a magnetic clutch. To check, drive the car with the A/C on. When it stops cooling, get out and see if the clutch is engaged. If not, carefully, very carefully, take a piece of wood, I used a broom handle, and tap the clutch. If it then engages, that is the problem. On the Volvo, the gap is set by a set of shims located underneath the clutch plate. The problem was resolved by removing the clutch and taking out a shim to get the gap back to specs. I'm not sure if GM does the same. If not, you will have to put in a new clutch.
Thread Starter
Heel & Toe
Joined: Jun 2013
Posts: 17
Likes: 0
Ok looks like I could have two problems, the connector and the low presure swith note all wireing to all switches on the 85 vett are black with no tracers. anyway I move the connector around the clutch would turn on and off, pulled connector spread the prongs on the swich, but there seems to be a 5 to 10 seconds delay some times not all the time for the clutch to come on, Also can the low presure switch be replaced with out draining the system?
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Racer
Joined: Feb 2012
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From: Seattle Washington
I have an 84 vette the ac has been converted 134a few years ago, the compressor has been replaced at the same time, now about 7 yrs later I had to replace the Schrader valve, because it was bent and would take refrig, So now to the issue, I refilled with 134a 2.75lbs as stated on the bower. I start the car turn on the ac it cools down to about 38 to 40 degrees for as long has the car is running, great, Now when I turn the car off after about 30 miles and wait about an hour or less and start the car and turn the ac on I get warm ac some time but not all the time I can get cold air but then it goes warm again any ideas, summer is here and it has a glass top. Thanks for any help.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Low Pressure Switch is on a Schrader so there's no need to discharge it - just unscrew it - and screw it back on - as fast as you can. Do use a little compressor oil on the o-ring and tight plus one turn is all it needs.
Clutch gap shouldn't exceed .020 inch. Check it with a feeler gage. I can't remember if the R4 compressor uses shims or if it's a press fit (which will take a special tool that's available at NAPA - so are shim kits). Fixing the air gap doesn't not require a discharge either.
Clutch gap shouldn't exceed .020 inch. Check it with a feeler gage. I can't remember if the R4 compressor uses shims or if it's a press fit (which will take a special tool that's available at NAPA - so are shim kits). Fixing the air gap doesn't not require a discharge either.
Thread Starter
Heel & Toe
Joined: Jun 2013
Posts: 17
Likes: 0
ok Seems that the problem was with the low presure connector, not the switch. when I touched the connector the clutch would tour on and off. So I took the connector off turned it 180 and no issues after that. got cold at 40dg seems all ok. Thanks for the help. I will need to start another thread because now the shuts down after coming off at trun but not all the time, mostly when it was in a tight turn.