Bad ac compresssor?

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Y

Yoter91

Joined
Jun 21, 2026
Threads
3
Messages
8
Location
USA
Just bought an 80 and drove it home 1000 miles. Had no issues other than ac stopped working half way thru. Old me would have just replaced every potential part it could be but this time im trying to make sure I have it narrowed down correctly.

AC compressor wont engage. I used a jumper on the pressure switch to see if it would come on and got nothing. Then I hooked 12v directly to the compressor and still nothing. Just got my set of manifold guages delivered and its reading a static pressure of 100psi which seems to be in the acceptable range. Safe to diagnose this as bad compressor? Anything I could have missed pls do tell me.

Thanks

20260630_185543.webp
 
Sounds like you have electric clutch failure or the air gap adjustment is incorrect. Gauges will tell you nothing without the compressor running other than you do have some refrigerant. Suggest you download the factory service manual from the Resources section of the forum.
It's also more cost effective to replace the entire compressor than just buying the clutch.
 
Make sure the switch on the HVAC unit in the rig is actually working. My button would not stay engaged and the AC would kick off.
 
100 psi is enough to make it engage. Could be the clutch like @Kernal can you turn the compressor by hand with belt off? This is to see if the compressor is locked up.
 
This happened to me like three times halfway through trips. I had switched to a brass radiator thinking it’s more robust. Turns out it was not the engine as well. When engine overheats there is a thermal switch on the engine block that cuts out the AC system to protect engine. Works otherwise in normal driving. I replaced three compressors at Autozone lots mid trips. Switched to a OEM Koyo radiator and problem was solved. Maybe your issue. How is the engine cooling??
 
ceylonfj40nut said:
This happened to me like three times halfway through trips. I had switched to a brass radiator thinking it’s more robust. Turns out it was not the engine as well. When engine overheats there is a thermal switch on the engine block that cuts out the AC system to protect engine. Works otherwise in normal driving. I replaced three compressors at Autozone lots mid trips. Switched to a OEM Koyo radiator and problem was solved. Maybe your issue. How is the engine cooling??
Click to expand...
Maybe good point could be a bad but he has jumped it at the compressor.
 
If you put 12 volt on compressor you should hear clutch click. If no click electric clutch burned out. Best option if this is case replace entire compressor. Make sure you are putting 12 volt on clutch. No broken wire on clutch.
 
I think 12volt positive goes to the wire lead off clutch and negative to housing. Also check your ac fuse if compressor checks out and ac relay
 
Last edited:
First time in real heat for my 80, AC kept stopping cooling on really hot day driving home on highway after day off-roading.

I could turn it off and back in, generally waiting about 1-minutes and flip back on to cold again for a few minutes then would happen again.

Engine temp gauge didn’t move from middle of range. Light for AC stayed on, it was all the way to left.
 
I didn't read all the comments, but here's how I'd start this process:
- apply 12vdc to clutch coil - CLICK? if yes, move on. If no, then investigate the clutch coil. Could have a broken wire inside, and you can buy just the clutch from the usual places.
- do you get 12vdc using a DVM on the clutch coil wire from the ECU at the compressor when engine is running, a/c set to full blast? If yes, move on. If no, then your ECU is not receiving a proper signal from something. Perhaps the pressure switch near the driver headlight? Your gauges read like a normal static pressure so from that perspective, the pressure switch should be happy.

These Denso compressors are built well and they don't usually fail at compressing the gas, but the clutch coil can fail due to age, or a noisy bearing may develop as well.
 
My pressure switch went bad. I had to disconnect it and jumper the connector. It was causing it to turn on and off about every 10 seconds. Was driving me crazy.
 
Not to hijack this thread but I just tried to charge my system the other day and when I went to light up the A/C the compressor was screeching something fierce so I turned off the button and the noise went away, turn on the button screeching. I was by myself so I couldn’t get anyone to hit the switch so I could see what was going on so I just decided to evacuate the system. You suppose the clutch is fried or the compressor is toast. I’d like A/C cause my wife and daughter aren’t cut from the same cloth as me. But I’d hate to throw a compressor at it just to find out the evaporator or condenser are plugged or what ever and since I can’t run the system I can’t see what pressures are doing for further diagnosis I assume the compressor clutch is toast. It’s got some aftermarket garbage compressor on it now so it could just be donezo.
 
MissahPapaJ said:
Not to hijack this thread but I just tried to charge my system the other day and when I went to light up the A/C the compressor was screeching something fierce so I turned off the button and the noise went away, turn on the button screeching. I was by myself so I couldn’t get anyone to hit the switch so I could see what was going on so I just decided to evacuate the system. You suppose the clutch is fried or the compressor is toast. I’d like A/C cause my wife and daughter aren’t cut from the same cloth as me. But I’d hate to throw a compressor at it just to find out the evaporator or condenser are plugged or what ever and since I can’t run the system I can’t see what pressures are doing for further diagnosis I assume the compressor clutch is toast. It’s got some aftermarket garbage compressor on it now so it could just be donezo.
Click to expand...
No, the clutch isn't toast, but your compressor is locking up, from the sounds of it. The clutch is actually doing a great job of trying to rotate the compressor, but the belt is slipping/squealing. Some kind of a debris was floating around in your closed loop system, and now found it's way into the compression chambers. So, I'd be looking into why this happened vs replacing only the compressor. This means, opening up the system, cleaning it thoroughly, replacing the drier/filter, pulling a vac, then recharging.

I'd conduct a search on how to do this fun job in this 80 section as I bet someone has done it already. I did a writeup on removing the evaporator behind the glove box, and it's in the FAQ thread.
 
Travis 76 said:
My pressure switch went bad. I had to disconnect it and jumper the connector. It was causing it to turn on and off about every 10 seconds. Was driving me crazy.
Click to expand...
his first post stated that he bypassed the pressure switch and still got nothing.
 
MissahPapaJ said:
Not to hijack this thread but I just tried to charge my system the other day and when I went to light up the A/C the compressor was screeching something fierce so I turned off the button and the noise went away, turn on the button screeching. I was by myself so I couldn’t get anyone to hit the switch so I could see what was going on so I just decided to evacuate the system. You suppose the clutch is fried or the compressor is toast. I’d like A/C cause my wife and daughter aren’t cut from the same cloth as me. But I’d hate to throw a compressor at it just to find out the evaporator or condenser are plugged or what ever and since I can’t run the system I can’t see what pressures are doing for further diagnosis I assume the compressor clutch is toast. It’s got some aftermarket garbage compressor on it now so it could just be donezo.
Click to expand...
I have had this happen on several cars and it was sometimes due to compressor not have been run for a long time. First check belt tension and condition of belt and pulleys including idler pulley. Rust or oil or glazed belts? If all checks out clutch surfaces may be contaminated. Hit the ac button on and off 3 times over a few seconds to clear the clutch surfaces. Let us know what you find
 
Last edited:
FJ80HI said:
I have had this happen on several cars and it was sometimes due to compressor not have been run for a long time. First check belt tension and condition of belt and pulleys including idler pulley. Rust or oil or glazed belts? If all checks out clutch surfaces may be contaminated. Hit the ac button on and off 3 times over a few seconds to clear the clutch surfaces. Let us know what you find
Click to expand...
Ya I thought similar things but I did cycle the compressor a few times hoping to loosen it up. But over 5-8 times I decided to throw in the towel. The belt is properly tight and less than 100mi old with a new OE pulley. But I’m positive the system hasn’t been in use for years I had no Freon when I evacuated the system and held vacuum for 25mins. When I pulled off the high side the Schrader valve sucked in air so I replaced all the valves and tried again to charge but it just wakes up grumpy guess I’ll pull of the lines and try to blow air through the system if everything is passing air I guess I’ll flush the system and replace the compressor with a Denso.
 
You must log in or register to reply here.

Share this page

IH8MUD Forum | Toyota, Lexus & Off-Road Community
Community platform by XenForo® © 2010-2026 XenForo Ltd.

© 2000-2026 Tie Rod Media LLC

Back
Top Bottom