A/C compressor question

[rowdyrabbit]

I’m trying to figure out if my compressor is locking up, or just the pulley going out. A while back the belt started squealing, so I tightened the tension. Helped a little, but didn’t fix it, so I replaced the belt. Still no dice. I was messing with it Saturday and noticed the belt was slowing and trying to stop. Found the tensioner idler pulley was bad. Bearing was shot. Replaced it today. Everything seemed fine, then it started locking up again. Pulled the belt off to check compressor. With A/C turned off, engine running, pulley spins free. With A/C on and engine cool pulley will turn, but doesn’t spin free. With A/C on and engine hot, pulley will not turn at all.

What does this tell me? Anything else I need to check? Compressor shot, pulley problem or something else?

Thanks

 

[Jgrauman]

AC Clutch

AC Clutch or Compressor

 

[rowdyrabbit]

I saw that second thread when I searched before posting my question. Mine acts and sounds the same, but it is not missing the tension bolt as that one is. I’ve tightened the belt nearly to the end of the tensioner bolt threads. I can’t imagine it’s still loose, but I guess it’s possible. Can you get the belt too tight? I’ve got a small amount left I could tighten, but I don’t want to risk messing something up.
Assuming the belt is tight, what would most likely cause the issues? It spins freely and no noise when A/C is off. Screams like crazy when you turn it on. But, only screams after it warms up.

 

[rowdyrabbit]

Can you get the belt too tight? No. The tensioner bolt will break first.

I was bored and thought that was something I could rule out without new parts. Pretty sure I had the belt tight enough.

Does anyone know off the top of their head what size that bolt is? If not, I’ll figure it out at the bolt shop tomorrow.

 

[MoJ]

Yes you can tighten it too much. The end of the adjustment range is too much. Spend $12 for a Gates belt tension gauge and verify it’s within the FSM spec. If it’s not within spec then you have other issues and are wasting time tightening it.

 

[ajax1]

Pop your idler bearing off first, remove the c clip and knock out the bearing, you can then open the bearing dust cover with skinny pick, clean it with brake clean, if it looks good and know spins easy then regressed I just used a little moly grease, put dust cover seals back on,smack bearing back into pulley, install c clip then reinstall. Put belt back on tension up and see if noise is gone. I did this along with inspecting clutch and bearing and mine is now noise free, where as before it would make a terrible squeal under load or when clutch engaged

 

[rowdyrabbit]

Replaced whole idler pulley today. Pulled it off and bearing was shot, so I replaced it. That did not fix the problem.

I’m not exactly sure how much resistance the compressor pulley should give when engaged. It turns easier cold than it does once the engine is hot. Once it’s hot, it all but locks up. I figure that tells me something, just not sure what.

 

[Dave 2000]

Has the system been refilled lately, too much gas? Expansion valve issue?

Bottom pulley not slipping at balancer, use a white paint stripe across the pulley.

Regards

Dave

 

[rowdyrabbit]

I refilled it a couple of years back. It did not show to be overfilled at that time. It was some time later before the problems started. But, it is possible it was overfilled.

The bottom pulley is brand new and looks to be tracking true.

Thanks for all of the help so far.

 

[rowdyrabbit]

Looking at it further, I’m certain it’s the belt squealing. The idler pulley is new and spins freely. The pulley on the compressor spins freely when compressor is off. It spins, but not as freely, with compressor on. As engine gets hot, pulley on compressor is almost stuck with compressor on.

I’ve read several threads on compressor problems and clutch problems. I cannot find a definite answer as far as how to tell whether the problem is the compressor or clutch. Or how to test to rule either out.

I’d like to know, or have at least a good idea, without just chasing parts. Thanks for all the help so far.

 

[Dave 2000]

I might of missed it but you did fit a new belt? If the belt (new or old) has been slipping, check the belt is not sitting the the bottom if the 'V' in the pulleys.



Regards

Dave

 

[rowdyrabbit]

That was the first thing I tried. I tightened the old belt then replaced. I used a Gates belt rather than stock, because that is what was available. I know many say the Gates belt will slip because it is segmented, but I do not believe that is my problem here. The belt on it when I bought it was segmented, and worked fine for a long time. I feel like the compressor pulley has more resistance than any belt can overcome.

How much resistance is expected from the compressor pulley? Both with and without compressor running. Does it mean anything that the compressor gives even more resistance when the engine gets hot?

 

[Dave 2000]

Could be a compressor problem, but before we go any further did you change the expansion valve?

Sometimes you can hear them 'zing' (technical term) when first starting the AC, I am unsure if a jammed valve may cause higher than acceptable pressure (load) on the compressor?

regards

Dave

 

[rowdyrabbit]

I have not messed with the expansion valve or anything in the cooling box. That seems like a pretty detailed job.

 

[Dave 2000]

I have not messed with the expansion valve or anything in the cooling box. That seems like a pretty detailed job.

They do fail, but the loss of cold air is the normal fail mode. Just wondered if it jammed it would allow pressure to build?

Not too difficult to change on a RHD car.

Regards

Dave

 

[Tools R Us]

... It turns easier cold than it does once the engine is hot. Once it’s hot, it all but locks up. I figure that tells me something, just not sure what.

The best hint to the mystery would be pressures. If the high side pressure goes way up when the belt slips, likely a flow blockage, expansion valve, etc. If not, more likely to be bearing, clutch, compressor...

 

[-Spike-]

FYI- If the problem is the clutch or compressor, the clutch is almost as expensive as the complete compressor. The only advantage to doing the clutch alone is the possibility of not discharging the system. But, then you have a new clutch on an old compressor.

 

[rowdyrabbit]

It appears it may have been overfilled. A little may have “accidentally” slipped out, and now no more belt slipping. I’ll watch it a bit and then fill it to the proper amount if it keeps acting right.

That was the easiest thing to check. I was going to have to empty it out if I swapped the compressor anyway. I figured it must have been building pressure as it warmed up, so that seemed the most likely to me.

Thanks again for all of the help.

 

[-Spike-]

It appears it may have been overfilled. A little may have “accidentally” slipped out, and now no more belt slipping. I’ll watch it a bit and then fill it to the proper amount if it keeps acting right.

That was the easiest thing to check. I was going to have to empty it out if I swapped the compressor anyway. I figured it must have been building pressure as it warmed up, so that seemed the most likely to me.

Thanks again for all of the help.

The pressure will rise with the temps. One theory- your fan may not be pulling as much air as it has in the past, allowing the pressure to get higher than it used to.

 

[rowdyrabbit]

That is possible. The fan shroud has been missing since I’ve owned it. I’ve never had any overheating issues, so I’ve not replaced it. I didn’t figure it would be too easy to find, but I’ve also not tried.