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ac compressor

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.
1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70
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volvomadness
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ac compressor

Post by volvomadness » Thu Apr 20, 2017 9:39 am

clutch is not engaging. System has enough freon. I jumped the pressorstat and the clutch engages.

Question? If clutch engages when i jump is the gap fine on the compressor or will it engage if the gap is still too large.

Thanks Madness



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abscate
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Re: ac compressor

Post by abscate » Thu Apr 20, 2017 9:46 am

It will usually engage when cold, then drop when hot. You can measure the gap to confirm, of course.

It is tough to confirm Freon amounts - the gauge on the can readings certainly won't be accurate


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Ozark Lee
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Re: ac compressor

Post by Ozark Lee » Thu Apr 20, 2017 11:09 am

The pressostat prevents the system from engaging if the static (system off) system pressure is below about 28 PSI. If you can get a gauge on it you can see if it is just low. If it is low then, sadly, chances are you have an evaporator leak.

...Lee


'94 850 N/A 5 speed
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abscate
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Re: ac compressor

Post by abscate » Thu Apr 20, 2017 12:35 pm

IS this for your 2003 V70? We should move it to the P2 Forum. Thankfully - these EVAPS go a lot less than the P80 cars.


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volvomadness
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Re: ac compressor

Post by volvomadness » Fri Apr 21, 2017 6:51 am

It is for a 850 97 I put a multimeter on the pressostat and the ohms does not read oo assume that the pressure is low.



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abscate
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Re: ac compressor

Post by abscate » Fri Apr 21, 2017 8:11 am

Low pressure or the pressostat has failed open circuit.

You need a good gauge to measure the low pressure side with the compressor running to verify correct charge.


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Ozark Lee
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Re: ac compressor

Post by Ozark Lee » Fri Apr 21, 2017 6:58 pm

The pressostat can fail, but it is really, really rare. Usually when the pressostat reads an open circuit it is because the system pressure has dropped below 28ish PSI. The static pressure of the system is not a good measure of the charge since it is so dependent on temperature but on a moderately warm day a pressure of around, or a bit above, 100 PSI would be in the ball park for a correctly charged system. The only remotely valid pressure measurements are made when the system is actually operating which is a catch 22 since it won't operate, or stay operating, if the pressures are to low.

You can do some real damage to the compressor if it is operating more than a few seconds without a correct charge since the oil doesn't flow without the refrigerant to carry it so be careful testing. You can get by with a quick on and off by jumping the pressostat but keep it quick. Your best course of action is to get a gauge on the system and see where you are.

...Lee


'94 850 N/A 5 speed
'96 Platinum Edition Turbo
'99 V70XC - Nautic Blue
Previous:
1999 V70XC - RIP - Wrecked Parts Car.
1998 S70 T5
1996 850 N/A
1989 740 GLT
1986 740 GLT
1972 142 Grand Luxe

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