A/C won't turn off: continuous run cold

[Sportriderseattle]

Car: 1987 Supra Turbo w/ 75K miles
Symptom: my a/c compressor will not turn off unless I hit the "off" button for the fan, therefore I can not use heat or just the vent air without the air conditioner compressor running. This is with the A/C button in either the on or off mode and that light illuminated.

This all came about after I took my car to get the R12 upgraded to the R134 (?). It blows nice and cold as it should when turned downward to 65 degrees and warms up to hot toward the 85 degrees, but with the air conditioner compressor still running. After the mechanic did the upgrade to the system they apparently found a defective wire which they had to replace since the compressor would not engage. They claimed it was probably a corroded wire.

So as can be expected I don't want to be driving around with the damn a/c compressor running all the time and killing my gas mileage. Any help or suggestion would greatly be appreciated.

**** See update below for 9/2/07, now just aint working ****

 

[antman]

So, the ac light stays on reguardless what position the ac button is in?

 

[GeneStarWindGSW]

maybe the actual CC has problems with it but hey man ur lucky to have AC lol.
if anything swap out the CC and try another one.

 

[tte]

You have any friends who also have supras?
Just do a quick CC swap and see what happens.

Cheers,
Roy

 

[antman]

thats my guess too

 

[Dracov]

Sounds to me like they bypassed your magnet clutch relay when they replaced that wire. Check the wiring underneath the junction block in the engine bay - just behind the battery - that's where the compressor clutch relay and condenser fan relays are located.

 

[Sportriderseattle]

thanks guys for your responses. I assume that "CC" refers to the compressor clutch. And to answer Antman, the green light on the A/C only comes on when the button is switched, but of course goes out when it's pressed again, that is while the compressor is still clunking away.

 

[IJ.]

CC in this case would be Climate Control

 

[suprahero]

First time I've ever heard about a MKIII owner complaining because his A/C works tooo good...........:biglaugh:

 

[glntom]

First time I've ever heard about a MKIII owner complaining because his A/C works tooo good...........:biglaugh:

If he lived in the south like us he would be bragging.....

 

[suprahero]

:word8kn:

 

[Sportriderseattle]

Well, the repair shop is now on day 3 (of just trying to diagnose why the a/c compressor is not shutting off) and they still have no idea why the compressor is not shutting off when the A/C button it turned to off. I had them check this wire and they said they did and that was not even the wire that got replaced. They just keep saying this is one very complicated a/c system and most of the wiring diagrams for this old of a car no longer exist.

It seems highly unlikely for an a/c wire to go bad and have some other component in the a/c to also go bad at exactly the same time!!! Wouldn't one agree that likely only this wire went bad and when the shop was making repairs, or doing their diagnosis, did something incorrectly or forgot something that caused the a/c compressor to not shut off?

What is a guy to do? Demand a full refund and take it to a Toyota dealership?

Sounds to me like they bypassed your magnet clutch relay when they replaced that wire. Check the wiring underneath the junction block in the engine bay - just behind the battery - that's where the compressor clutch relay and condenser fan relays are located.

 

[Ric]

undo the harness clip to the compressor.. if it's getting no power, the clutch should disengage. If it doesn't, the clutch is toast.

 

[jetjock]

While it's true the system is complicated it's not that hard to fathom when run in manual mode. Plus the wring diagram is readily available. Having the dash out helps when troubleshooting but it can be done in. Sounds like you need to find a better shop, preferably one that does nothing but AC work. I'd avoid the dealer.

 

[Aspec]

undo the harness clip to the compressor.. if it's getting no power, the clutch should disengage. If it doesn't, the clutch is toast.

Agreed. Unplug the compressor. If it shuts off it electrical, if it keeps going it's mechanical (clutch). Let us know and we will go from there.

 

[CPT Furious]

When I had this problem many years ago, it turned out to be a mechanic setup up the magnetic clutch relay to be engaged whenever the blower fan in the cabin was turned on. He justification was "that's how Corvettes do it." Anyway, I have since fixed it. The relays I speak of are behind the battery and slightly under the junction box.

Just another suggestion. I would also avoid the dealer. They WILL try to rob you blind...ask me how I know!

 

[Sportriderseattle]

okay, so the a/c is not working at all afterall. I finally got the shop to admit that the only way they could get the a/c going was to jump the compressor. They finally gave up after over a month in the shop off and on then refunding my money, so they unjumping the compressor and now it does not work. The last thing they did was replace the solar sensor in the dash which they said was bad, then the last thing they said was that it "appears" that the climate controller may be the issue as things were pointing to it. I purchased an updated unit out of a 91 and no changes whatsoever.

So I pose to you....If they got the a/c compressor to work by jumping it, could it be the clutch inside the a/c compressor? (maybe I should say is it more than likely) And if so, how much work is involved in changing out the clutch since I see they don't cost much online new which I found on ebay?

Or...any other ideas or suggestions? Thanks for your help.

 

[Sportriderseattle]

anyone that can help? * see post just above *

 

[Sportriderseattle]

see above

 

[suprabad]

:icon_bigg Move somewhere warm.