Strange PSI's in AC system, no cold AC

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Al9
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Re: Strange PSI's in AC system, no cold AC

Postby Al9 » Fri Jul 03, 2020 3:15 am

New clutch hub/pulley might be unburnished and slipping.
Last edited by Al9 on Fri Jul 03, 2020 4:15 am, edited 1 time in total.
Noquacks
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Re: Strange PSI's in AC system, no cold AC

Postby Noquacks » Fri Jul 03, 2020 3:40 am

Al9 wrote:New clutch hub might be unburnished and slipping.


Should I scuff it up with say, 100 grit sandpaper?
Al9
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Re: Strange PSI's in AC system, no cold AC

Postby Al9 » Fri Jul 03, 2020 4:13 am

New compressor installation instructions usually require to repeat a 10 second compressor engaged, 10 second compressor disengaged cycle a few times. Seen these "few times" range from at least 5 times to 50 times (yes, pretty boring messing around with an AC switch and chronometer thing). Engine idle. Both the pulley and the clutch hub friction surfaces have to take some wear to properly engage.
Noquacks
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Re: Strange PSI's in AC system, no cold AC

Postby Noquacks » Fri Jul 03, 2020 2:58 pm

I finally got the new clutch on as well as the plate! I decided it was time to yank the old clutch as its surface was sooo nice compared to the old. Put it all together and gapped around 0.017-0.018, and works nice meaning clutch does not skip/squeal anymore.

Thanks to all here who patiently supported me and my problem! You guys are great!! (if it wasnt for the advice here I would have probably got a new compressor, not knowing about the clutch failures.)
Noquacks
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Re: Strange PSI's in AC system, no cold AC

Postby Noquacks » Fri Jul 03, 2020 3:45 pm

OK, excitement was too early as I took it for a drive and the car engine lurches/kicks/bucks a lot when the ac runs. on/off, etc. Air is not that cold. Could it be the magnet that came with the clutch kit whiuch I did not install? Should I test that old coil?
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Tim
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Re: Strange PSI's in AC system, no cold AC

Postby Tim » Fri Jul 03, 2020 4:04 pm

Clutch/Pulley smooth with a/c off?

If so compressor is toast. Can't turn locked up pistons.
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Al9
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Re: Strange PSI's in AC system, no cold AC

Postby Al9 » Sat Jul 04, 2020 3:33 am

If i'm not mistaken he has a Sanden scroll. In that case it's likely the compressor body's temperature switch, either misbehaving or doing what it's supposed to do.

Might be a good time to have a pro service the system and rule out any undercharge/overcharge condition (or leak).
Noquacks
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Re: Strange PSI's in AC system, no cold AC

Postby Noquacks » Sat Jul 04, 2020 4:12 am

Tim wrote:Clutch/Pulley smooth with a/c off?

If so compressor is toast. Can't turn locked up pistons.


Good tip, Tim. Im trying to remember- when the belt was off and I was removing the pulley (clutch) I was trying to turn it to pop it off and yes, it was sometimes hard to turn the pulley so that would mean that the piston is stuck/stiff inside, right? I think we are finally onto something. I am prepared to replace the comp if necesary.
Noquacks
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Re: Strange PSI's in AC system, no cold AC

Postby Noquacks » Sat Jul 04, 2020 4:15 am

Al9 wrote:If i'm not mistaken he has a Sanden scroll. In that case it's likely the compressor body's temperature switch, either misbehaving or doing what it's supposed to do.

Might be a good time to have a pro service the system and rule out any undercharge/overcharge condition (or leak).


I didnt know one can determine if a system is under/overcharged, How do you do it? With guages? And if a slow leak, how does that make the 'comp act so violently? I think if system would be low wouldnt the system just not work/be shut off with absolutely no cold ac?

So far, I tending toward a new comp. Anyway, thanks again people for helping with my big problem.
Al9
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Joined: Tue Mar 10, 2020 3:26 am

Re: Strange PSI's in AC system, no cold AC

Postby Al9 » Sat Jul 04, 2020 4:28 am

What i said is that your compressor, like most early rotary (vane or scroll) compressors, has a temperature switch that is meant to cut the clutch off (it's in series with the clutch) whenever the discharge temperature gets too high. An undercharge results in higher than normal superheat and this causes higher than normal discharge temperatures. But the switch itself might also be faulty. Might have noticed that strange wiring setup yourself while tinkering around. Until the high side pressure gets terribly low i doubt the compressor clutch will plainly stop engaging due to low refrigerant.

With modern TXV systems, only reasonable way to determine that the system has the proper charge is to have someone recover any leftover refrigerant, weight it, vacuum the system and then refill it by weight.

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