mrfileio

1997 4runner, 6cyl, 210K miles

My AC compressor or clutch recently started intermittently seizing causing belt screech.

It's strange in that, with AC off, no bad noises from clutch/compressor/tensioner/belt. Turn on AC, clutch engages, cold air starts blowing, every thing normal for 15-30 seconds and then, looking at the compressor from the front, pulley stops for a couple seconds and the AC belt screeches. Then pulley starts to turn again, all is well for another 15-30 seconds. Rince and repeat.

When AC is running between screeches, it doesn't appear like there is any undue strain on the motor.

Oh, belt is new, good tension on the belt via the tensioner. That isn't it.

So it appears that either the clutch or compressor is binding but "unbinds" after a couple of seconds. I would think it would be all or nothing.

I'd like to troubleshoot by disconnecting belt, engaging the clutch by jumping from the battery (engine off), and turning the pulley by hand to see if I could hear or feel what might be binding. I couldn't find any pics of where to apply the +12v DC to the clutch/compressor to get it to engage.

Any thoughts on the problem or troubleshooting? Of course I hope it is the clutch but fear it is the compressor.

One other side piece of info. I had terribly leaky valve cover gaskets for years. Just did that job (and timing belt) but spent a lot of the time cleaning stuff. The AC compressor does have a pretty good coat of old engine oil on it. Like I said though, belt and tensioner are new and clean respectively.

tunnelmotor99

Sounds like either the bearings inside the compressor are shot or there is some other catastrophic internal failure happening. Either way, you need a new compressor. Take the belt off until you can replace the compressor so you don't contaminate the system with metal shavings and ruin the new compressor. Oh, and unless you have access to a recover/vacuum/recharge machine, you will need to go to the dealer or an independent shop. Good luck!

rjaudi

Mine did the exact same thing. Made a screeching noise for a couple seconds and then it went away. I removed the belt and when turning the compressor pulley I could hear a faint metallic sound. I replaced the compressor and it is completely quiet now. I took it to midas they removed the freon. Then I replaced the compressor and dryer. Then took it back to Midas for it to be vacuumed and recharged. I found a brand new denso compressor online for about 260 if I can remember right. The clutch alone is almost that so you replace the whole unit. I should have replaced the expansion valve looking back now.

mrfileio

Thanks for the replies. I'm going to go the same route. Denso online including drier and shop to drain and refill. 2 out of 3 AC techs I talked to recommended I change the expansion valve too.

profuse007

what are the pressures?

waskillywabbit

iTrader: (-1)

Remove and replace.

ISFast

I guess I might be confused but the reason people think it is not the Clutches is due to it is not blowing fuses like mine is?

https://www.yotatech.com/forums/f2/c...-could-214151/

skyratcalls

Mine did the same thing. I cut the belt off planning to fix it immediately, but that turned into about 4 years. I just got motivated to fix it (I am getting old and it is hot). I really did not want to spend a mint on the thing, and new compressor would have been great, but.... I took the compressor off and found that the clutch bearing was locked up. Found a bearing on ebay for $19.00 and a new clutch coil for $19.00. Replaced both. The bearing dimension was 52mmx30mmx20mm. Changed the drier and expansion valve. By the way, when changing the expansion valve, you can not seperate the lower and upper part of the cooler box while still in the truck. You have to remove the blower motor (not that hard), unbolt the refrigerant lines at the firewall and pull them throw the firewall with the complete cooler box and its contents. Now you will see the screws and clips that were hiding behind the cooler box and get to the expansion valve. The copper wire on the expansion valve was solder to one of the lines, I cut it off leaving some and soldered the new copper wire to the old one, I don't know if that was the correct method or not but it worked. Replaced all o-rings with the green ones (~$5), new expansion valve and drier (~$60), new bearing and coil (~$40), r134a (~$30 or so). Nice cold air about 43 degrees at the vent for under $150.00. Yeah a new compressor would have been great and best. But, if your coolant has not leaked out, you can simply repair the clutch without opening the system.

Good luck.

stinger381

I just had the same problem .... My belt would lock up and it would melt the belt and then it wouldn't tighten back up because it had a rubbed flat spot on it. Turns out it was the belt all along. I was buying the cheap belts from O'Reilly's and they didn't fit the groove of the pulley correctly. I bought the more expensive belt from CarQuest (green line belt) and it now works great. The belt was getting stuck in the compressor groove with the old belt not fitting correctly. The new belt is working flawlessly.