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Old 10-25-2011, 11:00 AM   #7
Registered User
Join Date: Dec 2010
Location: MD, USA
Posts: 1,489
My Ride: 01 330CI 6MT ZSP EU3
Continuing my A/C challenge.
All of the above actually may indicate that pressure sensor is indeed faulty. The good thing is that it costs just $42 at and can be replaced w/o evacuating refrigerant (there is a valve similar to high/low pressure valves for connecting gauges). However, here is what worries me: when the A/C system is completely off (engine is running), I must see equals low and high pressures on gauges, correct? This wasn't so when I did check the pressures, even though A/C was off I saw something like 50 psi on low side and 150 psi on high side. I am going to redo this test by connecting gauges to completely cold and not running car to see if these pressures are still different or not. After that I'll heat up the dryer/sensor to start the compressor, wait for some time to stabilize and turn off the A/C. Measure pressures. If they are different now....
What can this mean, especially in conjunction with pressure sensor readings in INPA? Blockage in the dryer/receiver, this is what comes first in my head. So, here what possibly happens:
1) there is a blockage in the dryer, that leads to higher high side pressure
2) this blockage is located AFTER the high pressure port but BEFORE the pressure sensor (either in the pipe or most likely in the dryer)
3) therefore, the pressure sensor may be perfectly fine: there is really no pressure at that point because of blockage.
4) after I heat up the dryer the blockage becomes smaller, it allows some refrigerant to go through. Not completely though, since after turning off the A/C I don't see equal pressures (will verify again, though). Also, not sure how precise should be the reading from the sensor in INPA, but it shows 11 bar utmost, whenever my gauge shows 230 psi (around 16 bar).
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