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Discussion Starter #1
I searched and read a few threads.

With the defroster on, a get a periodic grinding and the pulley on the AC compressor appears to stop. The idler pulley also flexes more than usual.

I removed the belt and the pulley does not spin quitely. It doesnt bind, but it makes a sound like there is sand in it.

I read that if I unplug the compressor connector, that the clutch is disabled...its just spinning the pulley - and the compressor should not spin. Is this right?

I did this and the idler pulley did not flex/bounce like it did before.

I am trying to avoid killing the compressor and filling the AC system will debris while I try to diagnose this.

How can i determine if its just the clutch or if the whole compressor is bad?
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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Yes, unplugging the clutch will prevent the compressor from engaging.

Try turning the compressor clutch (not the pulley) by hand. There should be at most 7 ft/lbs resistance. If there is more, the compressor is bad and debris may already be in the system.
 

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Discussion Starter #3
turning the clutch...that would the the outer/front part of the pulley?

i guess i should i turn the clutch with the belt off again? 7ft/lbs should be very little to no discernable resistance. i also assume it should not make an audible sound either?

thanks for reply!!
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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No, it shouldn't make any real sounds, other than perhaps an air pumping sound.

Yes, the front part of the clutch is what you want to turn. You don't need to remove the belt to turn the compressor part of the clutch.

However if you take off the belt and spin the pulley, it shouldn't make any awkward sounds either. If it grinds then you need a new pulley, which comes with part of a new clutch assembly. Since you say it sounds like there is sand in it, I'd venture to say your bearings are shot. If you end up having to replace the compressor, new units come with a new clutch.

FWIW, when I had to replace my compressor due to seizure, I spent about $400 in parts and tools to flush and rebuild the system. That includes a recharge at at a local shop.
 

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Discussion Starter #5
yeah, the pulley making a sound seems like at min the clutch is shot.

i just went down and tried to turn the clutch with the belt still on by hand....i couldn't turn it. i put a long screw driver across the front and couldn't really turn it either. seems like i should have been able to. i'll try it on my other tbird tomorrow daylight for comparison.

i'll bet the damn compressor is siezed.

i can replace the compressor hardware but i'm not confident i can flush the rest of the system reliably. wish i knew a reliable local ford service tech.
 

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Discussion Starter #6
just to help future searchers.

i went and turned the AC clutch on my other tbird and it is very easy to turn my hand...can just about spin it with the belt on the pulley.

clearly my other tbird has a seized compressor. i think they call it the black death in AC circles.

looks like i am going to drop about $2K at the lousey local ford service dept.
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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If you have the time and a decent compressor, a flush gun will run under $100; you can use lacquer thinner to flush the lines and evaporator. I ran a couple hose lines in/out of the flushed areas so I could re-use the flush solvents and filtered it twice using coffee filters each time I used it over. You're not supposed to flush the condenser but I did and haven't seen any issues.

I guess the first thing I'd do in your case is pull the liquid line from the condenser and see what the orifice tube looks like; that will indicate how much crap made it into the system.

Oh and be sure to replace the low side cycling switch. The cause of my failure was that someone had hotwired it on all the time so the compressor was always running. If yours is bad it might be causing the same thing.
 
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