Charleysnoop

Need help with wife’s car.
81 Vette with AC compressor problems. The compressor is new just installed. However the clutch clicks on and off every few seconds.
Jumpered it with a different battery and it runs like a charm.
Can someone out there give me some clues what the problem could be.

slickfx3

'
check the diode

Kevova

If you have gauge set what are high and low side pressures? It could be low. If DIY, did you evacuate and recharge it? Was orifice tube replaced? What else was changed?

4SPDL81

Did you re-service with freon?

chevymans 77

Its more than likely low on freon,

Neal

Charleysnoop

Thank you all, The Compressor was installed in local shop only assuming freon level
is correct. He installed new condenser and compressor also new manifold hose.

Kevova

I would just take it back in and have them look at it. Most likely low on gas. Negotiations in order if something else just happened to fail.

Charleysnoop

Back to the shop it goes.
Also I am new to the forum so thank you everyone...

Rmodeler

Don't mean to hijack in on this thread, but I just had the same thing done on my 82. At idle speed the compressor runs off/on every 4sec(sometimes it runs continously), go above 1200rpm and it will do the same thing, only faster-every sec or two(even with a/c lever turned off). Also, is the auxillary cooling fan for additional engine cooling or is it tied in with the a/c? The wiring diagram looks like it is only for additional engine cooling. They told me at the shop to troubleshoot the htg/ac controls to make sure they were operating ok, I can hear dampers opening and closing, vaccum to heater water shut off(because it was putting out cool air and not cold air). The heater hose seem to cool off when vaccum is applied to control valve. What would make the compressor cycle all the time, regardless of where the control is set??

68blvert

Rmodeler...a control switch not killing power or a short to power on the compressor clutch circuit will cause clutch to engage. it still should not short cycle though unless it is low on charge. auxillary fan is for engine cooling only. controlled by temp switch in cylinder head.

Kevova

Check your pressures. At least low side if pressure is dropping below 25psi when compressor kicks out it low on refrigerant. If you changed it over to 134a , I would add the 134a with dye in it. You want to check service ports ...same as a bike tube if it blows bubbles its leaking. If your still on R12 you may want to change it it over to 134a.

Hot water valve turns off coolant flow to heater core max with control in control in max a/c and temp full cold.

Air has to blow across condenser or high side pressure will be too high. normally excessive high side pressure does not cause rapid cycling.

hugie82

The compressor will be turned on in the AC selections and the defrost position. The constant on-off every few seconds is usually a low freon situation. The damper has an adjuster built into the cable so you can adjust it. If you take off the carpeted console panel on the passenger side you'll see the white plastic section on the cable. It is threaded and can be adjusted with your fingers. This will give you the ability to ensure the damper is sealed tight for cold air but you'll need to check your freon level before doing anything. Good luck.

Rmodeler

Thanks, trying to get as much information as I can, so when I take it back to the shop. It was switched to 134a w/dye. I do need to make a little extension to the vaccum control behind glove box so the lever pushes against the vaccum switch, I temporarily made an extention to the control to make sure I was getting vaccum to the heater shut off.

Kevova

For compressor to always be engaged regardless of control setting I would look for a fault in control at dash; melted connector or shorted switch within control. Melted connector at compressor relay allowing a short to voltage is also possible. Relay is not shorted and working since kick outs compressor. Somehow 12v is getting to compressor relay so that clutch will engage. With key on and engine off you should hear clutch click on, if you can wiggle wiring and hear clutch click off it may help find cause.

jim in oregon

yes..The glove box interior will come out with a short blade phillips screwdriver removing the six screws..two to front, two bottom front and one each side..You will need to pull the little bulb for the glove box lite and gently wiggle pull the socket toward the cabin to get it free of the glove box interior.Then you can see the cable attachment to the water shut off vacuum switch..and see IF it's closing properly. The cable can be adjusted without tampering with the ends by removing P/S console panel and using the turnbuckle provided on the OEM cable....When temp control lever is on COLD.. OFF..the cable bypass valve is depressed to open two vac lines one of which closes the underhood heater line water to the heat box and opens the dampers and stuff for the air to flow for vent and A/C..JIM

Rmodeler

Where is the actual location for the compressor control switch. The shop manual shows the schematics(?), but not the actual location, looks like it is on firewall near the distributor

jim in oregon

if you look under the hood passenger side, the off-on relay should plug into a socket on the firewall right above the black heater box affair..About big as five fig newtons..prolly has five flat prongs..Dont think that is the problem.New one is about 11 bucks at most auto stores..Napa etc..Jim

jim in oregon

The relay has 3 black 'quick' electrical connectors..2 wires in the top one, a single wire in the middle one and 2 wires in the bottom one..I KNOW because your car is same as mine in that regard..77-82 had many of the same components..jim

Rmodeler

Looking at Fig. 1B-3--C60 wiring in 82 shop manual:
When the a/c lever is put in the off position(clear to the left), is there a disconnect/switch at the electrical connection the lever that shuts the current off to the compressor? When in this position the fan shuts down, but the compressor clutch is still energized? When the LT green wire(brn is feed) leaves here it goes to the pressure sw, then to the compressor control sw. Could one part of the electrical selector switch for the a/c be bad?

jim in oregon

UNLESS you have selected A/C the compressor should Not cycle in or out.

FWIW..I believe the fan as selected on the console from lo to high does run in low even with everything off including the fan blower lever down like OFF otherwise for cabin air circulation.
I still think your issue is in the temp control-cable mechanism and the two vac lines that it opens or closes in response to the temp lever.All the other functions are vac controlled by the mode lever?
The relay underhood get's it's cue to close to operate or shut the A/C compressor off in response to the temperature sensing capillary to the evac-dryer in the A/C system..IF THE System is low on coolant.(R134A.. takes about 80% of the pressure the old R12 coolant required.that WILL MAKE YOUR COMPRESSOR cycle on-off quite often.Jim