I came back to town from deer camp to hopefully address this compressor noise. I need a temp fix so I can get back to camp. It started growling with defroster on, not a belt squeal but a growl like bearing or internals. Not real sure never had an AC go bad on a vehicle. I don't want to get up in mountains and have it seize and burn my belt off. I thought it was alternator up at camp, but is ac compressor for sure.

AC is empty, non working for sometime now. I searched and found ac delete pulley options, tracking down parts could take atleast few days IF I find the right bracket.

In a nutshell, can I make this compressor function as a free wheel so it will not lock up and burn my belt off. I know nothing of the ac clutch, can it be disabled to free wheel like a idler pulley, if so how ??

1990 4.0 aw4 sanden 508 compressor

 

Is it making noise even with the A/C or defrost off? If not, just unplug the connector that goes to the A/C clutch.

 

If it is growling only with the defroster on, it could just be the clutch. This also indicates that the system is NOT empty - there's a low pressure switch that wouldn't let it cycle on. Trace back the two wires coming off the clutch assembly and there will be a connector, just unplug it and see if your noise goes away.

On this compressor, there is a static shaft that the pulley rides on so there's no "quick" way to do a total bypass other than a delete pulley.

 

I had to do the delete pulley this summer. I had a growing noise, then a locked solid compressor.

 

So I disconnected the clutch wire and the noise is gone for the most part with defroster on. Closer inspection today, Noise is loudest when first revving rpm's up AND when rpm's rev down right before idle. Kinda like grinding to a stop.

I'll rip it off after hunting season and drain compressor oil to see if any shavings are present, possibly just needs a bearing and clutch. I'll put some gauges on it to see pressures as your right it shouldn't run without r-12 in it. The last time it was charged it worked for awhile then cooling stopped so I figured freon leaked again. I didn't bother putting a gauge on it because I was done wasting money on expensive r-12. If I can rebuild compressor, I got one can left to maybe top it off.

 

Was yours making noise without ac or defroster on ? Did it go pretty quickly after noise first appeared ?
Local wrecking yard want an arm/leg for parts lately. LKQ bought up most of the u pull its and closed them to entry. So i am not too confident finding a delete setup locally. I priced a 91-93 bracket and delete pulley at around half the price of a new compressor, so far. $65 for a used compressor is no deal either. I will go with new before paying that much for used.


Thanks for the replies.

 

Just a tip for when you put it all back together again. If you also put a new drier on it and clean the system of all the old r12 oil, r134 oil and charge works just fine in a system and compressor originally designed for r12. And they make adapters for your fittings.


A good friend of mine who owns a jaguar shop in hollywood figured this one out back when they first outlawed r12 and were scamming the whole country for outrageously expensive retrofit conversions. I have since done many of these myself with no problems.

 

Maybe not for you, but for the thread, not sure what years this works for besides 87-90 >

AC Bypass/Idler pully. (unconfermed) > Get an AC bracket from a 92, go to NAPA to pick up a Dorman AC bypass pulley for a 92 and newer. NAPA # p/n 660-1819. The belt size remains the same. You need to use the pulley spacer that comes with in the hardware bag, it moves the pulley out about an 1/8" so that it lines up perfectly with the rest of the stock pulleys.

 

AC clutch should freewheel when not engaged. If its engaged all the time then the clutch is broken and dragging. You can replace just the clutch and bearings, that won't require you to evacuate the system.

 

Sounds exactly like the clutch bearing going out - in a pinch, you CAN sometimes get a couple extra days out of squirting some SAE 30 oil in the clutch/bearing. It is a quick/easy change if you can source the bearing (or better yet a whole clutch kit) without it killing you on time.

Generally once a ball bearing starts making audible noise, it is too late to save it.

 

I might have to yank this one and check the bearing and clutch then top it off and see if it still blows cold. Thats' the beauty of this setup, it has service valves to close off system and remove compressor for service with out loosing freon. If a new compressor is needed then I'll probably go that route.

Yeh I seen that thread in my search and led me to the stock setup for non ac 4.0. 87-90 seems likely the only years with that 4.0 version, 87 was the new redesign year. Napa around here do not carry that part # but I found the Dorman #'s at their website. Dorman #34171 Air Conditioning Bypass Pulley
Application Summary: Jeep Cherokee 1993-91, Jeep Comanche 1992-91, Jeep Wrangler 1995-91. There is 3 different pulleys for the 4.0 years apparently.

Disconnected clutch wire and it is discoing when I turn on defrost, so thats all I really needed short term.

I need to price out those parts and double check my pressures. Last couple days discoed it has been quiet. Put about 200 miles on her. Yeh, I know rolling the dice I am.

Thanks again !