Diagnosing bad AC compressor

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Diagnosing bad AC compressor

Post by Hodgdon Extreme » Mon Jun 01, 2020 7:29 pm

I'm not an AC guru, but I think I've diagnosed my AC compressor as bad. Would like other's thoughts:

2002 Lexus IS300, 140k miles, owned it a couple years, AC always worked great

This spring, I noted warm air coming out the vents. AC clutch is definitely engaging and compressor is turning, but no strange sounds at all. Hooked up the gages and I have 100psi on the low side, and 100-105 on the high side - that is while compressor is engaged and turning. AC clutch does not cycle on and off. As soon as you call for AC, it engages and stays engaged. No noticeable change in engine load when this happens.

Tried to put a little refrigerant in it anyway (cause that's what you do when your AC doesn't work, right???) and obviously, the low side pressure was higher than the can of refrigerant - so no flow into the system.

Also, during operation with the gages hooked up, I had no flow through the sight glass.

Seems obvious to me the compressor isn't doing jack shit - but I'd love for someone more experienced than me to confirm/deny my findings!

If it needs replacement, I'll be changing the compressor, condenser, expansion valve and drier - because my understanding is that's the "right" way to do it if/when a compressor fails.

Thanks in advance.

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Re: Diagnosing bad AC compressor

Post by Bateman » Tue Jun 02, 2020 8:53 am

I’ve never had one not Lock up when they go bad, but obviously that’s not always the case.

I’ve got away with not replacing the txv when it’s a dash out ordeal. Mainly just came in here to say that I used BuyACParts.com. Believe it was like a year or two warranty, but anyways all of it was about $200. Compressor, condenser, oil, orings, everything. Still blowing cold 2+ years later.

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Re: Diagnosing bad AC compressor

Post by vehicular » Tue Jun 02, 2020 2:24 pm

The fact that it's throwing the magnet on the clutch, but not compressing refrigerant says the clutch isn't actually functioning to me.

Either way, most modern compressors aren't serviceable so you're probably going to have to replace the whole assembly simply because you can't get a clutch.

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Re: Diagnosing bad AC compressor

Post by BloodFart » Tue Jun 09, 2020 10:51 am

Not to hijack, but also having Lexus ac issues. 05 LS430, 150k miles, AC blows warm when car is 1st started. After restarting, blows cold rest of the day. Only does this during the hot summer months, during spring and fall AC works normally. According to the gauge on the ac can (I know) refrigerant level is good. Is this also a compressor issue, or pressure switch, or who knows w/out gauges. What shop would you guys use? DK Auto, or ?? Gracias
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Re: Diagnosing bad AC compressor

Post by Hodgdon Extreme » Tue Jun 09, 2020 2:15 pm

Is it engaging the compressor on that first call for AC?

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Wilson!
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Re: Diagnosing bad AC compressor

Post by Wilson! » Tue Jun 09, 2020 9:15 pm

System may be full of air. Need to evacuate the system, pull a vacuum and properly charge it and go from there.

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Re: Diagnosing bad AC compressor

Post by Hodgdon Extreme » Wed Jun 10, 2020 2:03 am

Wilson! wrote:
Tue Jun 09, 2020 9:15 pm
System may be full of air. Need to evacuate the system, pull a vacuum and properly charge it and go from there.
Are you referring to my issue?

If so, how could my system go from full of good refrigerant to fill of pressurized air?

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Re: Diagnosing bad AC compressor

Post by Wilson! » Wed Jun 10, 2020 9:11 am

It happens. Seen it many many times. I’m not saying you don’t have an issue, but the only way to properly diag it is to evac/recharge and see what what it does with a known good charge.

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Re: Diagnosing bad AC compressor

Post by Hodgdon Extreme » Wed Jun 10, 2020 9:17 am

I don't see how I could have anything other than a known good charge, already.

It worked great. It hasn't leaked.

What am I missing?

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Re: Diagnosing bad AC compressor

Post by Hodgdon Extreme » Wed Jun 10, 2020 1:19 pm

Anybody know where I can get a refrigerant recovery tank emptied?

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Re: Diagnosing bad AC compressor

Post by OMGWTFBODY » Wed Jun 10, 2020 1:24 pm

Back yard. :mrgreen:
STeeL wrote:Not a bad price for unlimited dicks.

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Re: Diagnosing bad AC compressor

Post by Hodgdon Extreme » Wed Jun 10, 2020 1:41 pm

OMGWTFBODY wrote:
Wed Jun 10, 2020 1:24 pm
Back yard. :mrgreen:
I'm no tree hugging hippie, but that is just wrong and irresponsible.

RE Michael will take a full one and give you back an empty one - but you must have an HVAC license...

Can't understand why the powers that be would want to add a roadblock to the responsible recovery/recycling of refrigerant. I can *sort of* understand the roadblock to buying the refrigerant - but surely not the return.

So - anybody here have an HVAC license that's willing to perform the tank swap-out for me?

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