Volvo 850 Made from 1993 to 1997, this Volvo line was available in both a wagon and a sedan, both with were graced with several trim levels.

850T wagon airconditioner not working....

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  #1  
Old 05-25-2015 | 02:35 PM
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Default 850T wagon airconditioner not working....

Hi,
I'm trying to figure out exactly why my a/c won't work on a Volvo 850T (95).

It doesn't blow cold air, so I refilled the freon, and as far as I can tell that's all good. BUT when I turn on the a/c, the compressor (?) turns on for about 2 or 3 seconds (like a motor revving up...) then turns off...then on again...off again etc.
I can see the bottom "wheel" starting and stopping (see photo).

Any ideas on where to start with this?

Thanks,
Alan.
 
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Old 05-26-2015 | 01:03 PM
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Sounds like your car is still low on freon. The AC compressor needs to be running to take the charge so the procedure for filling a low system is to jumper the low pressure sensor (up near the firewall on the return line) by removing the connector and bridging the two pins with something like a paper clip. If you AC now stays on for more than the 2-3 seconds then hook up your pressure guage/refill kit and repeat the fill process with the sensor jumpered. If your pressure gauge says you are already filled then I'd suspect you may have a fault in either a high pressure sensor (down on the condensor) or the low pressure sensor. To replace those you need to remove all the freon so it becomes a hassle as you should then consider changing out the orifice port and the dryer as well as any o rings.
 
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Old 05-26-2015 | 09:13 PM
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OK, thanks.
I'll try to jumper the low pressure sensor and see how that goes.
Alan
 
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Old 07-01-2015 | 12:33 AM
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Default Resolved....

Thanks for the tip...I jumpered the sensor as you recommended, and was able to fill up with freon. I had tried before but couldn't understand why the freon wouldn't go into the a/c compressor...all very frustrating because I took it to an AC guy last summer and he told me the compressor was not working and it would be $900 or more to fix it...I know it's a complicated thing to to replace and he didn't seem too keen on even doing it (and I was even less keen to spend so much money on a 20 yr old car!).
Is that common for all cars to not have the compressor come on if there's no freon in the system...?
Anyway I'm delighted to have it repaired, having suffered thru last summer with no a/c!
Thanks again for your assistance!
Alan.
 
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Old 07-01-2015 | 10:51 AM
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most newer designs have both high pressure and low pressure sensors to protect the compressor from running without freon (low pressure = no oil gets to the compressor) or high pressure (usually from a blockage or accidental overfill) which may blow out seals/evap/condensor bits etc. You can get a system leak (the evaporators are prone to corrosion when the drain is clogged and condensation puddles at the bottom of the evap) or o-ring leaks - which means you may need to do seasonal recharges until you find the leak with a dye test. Another common failure is the AC clutch - compressors don't generally fail outright. When the clutch wears over time the gap can get too large to allow proper pressure and it slips creating heat and the system will shut down after a few minutes. You can reshim without opening the AC system (some write up are available online). If you decide you need to replace the compressor, rebuilt compressors are available at a fair price on ebay but you then should rebuild the system (anytime you open up the system you add moisture to a closed system) ie new orifice tube, new accumulator (this captures excess oil/freon as they system cycles on/off), freshen the o-rings and do a measured recharge with oil. A dye test is recommended before opening the system to make sure you don't install a new compressor etc only to have a leak in another part like the evaporator or condensor.
 
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Old 07-01-2015 | 11:56 AM
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Thanks,
I'll keep an eye on it and see how it fares over the next two months; it's possible there is a slow leak somewhere, but so far it seems good.
Really appreciate all your input!
 
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