From digest.v7.n1413 Tue Mar 31 00:29:48 1998
From: Rick & Lisa Westerfield <73237.2070_at_compuserve.com>
Date: Mon, 30 Mar 1998 22:41:17 -0500
Subject: 1989 325is A/C Problems <Kinda Long>
Hello Bimmersg & the Digest,
You do not mention if your A/C service place has put your car on the
manifold gauges or not. And hopefully, most of the simple stuff has been
checked but more on that later. It almost sounds like they like to
practice "SWAPTRONICS" with your money and A/C until they get it right.
Find another service center if this continues. Has your system been
running this winter with the defroster? Or has it possibly been open to
the atmosphere since last summer? If it has been down for a long time,
it could have picked up a big load of moisture. Only a good long pump
down or maybe two will rid you of this moisture. The water can freeze up
your expansion valve.
From the Haynes A/C book and several years of tinkering with the
Behr/York A/C in my 75 2002 and retrofitting a Behr/Frigiking A/C into my
brother in law's 74 2002, this is what I have to suggest:
Does the compressor clutch engage fully when it is supposed to? Or does
it slip intermittently? Check it for a loose power and ground wire.
Does the belt or clutch slip after the compressor has warmed up? Is the
fan in front of the condenser/radiator running properly? What is the
receiver-dryer (R-D) sight glass telling you - any bubbles? Does the
compressor stay on all the time or does it cycle normally? Or not at all
when you have your problems?
Are any of your vacuum lines loose or broken inside the dashboard? These
could allow the plenum doors to stay closed thus robbing you of cold air.
Does the evaporator stay cold to touch even though you get no cold air?
There are many manifold gauge combination readings that can tell a lot -
Low side gauge - hi pressure and compressor cycles at too high of a
pressure = defective thermostat or incorrectly adjusted
High side - higher than normal pressure = excessive moisture in system that
may freeze up at the expansion valve thus blocking your system after a few
minutes of operation
High side - higher than normal pressure and low side lower than normal
pressure accompanied with R-D lines and liquid lines being cold to the
touch(or even frosting) = screen in R-D is clogged
Low side - high pressure accompanied with excessive moisture on the
evaporator/suction lines = expansion valve thermal bulb has lost it's FREON
charge - BTW, this bulb line is fragile and easy to break
Normal pressures but warm air at the vents or slightly higher than normal
high side pressure and a lower than normal low side pressure = the screen
in the expansion valve is clogged
High side gauge is normal and the low side indicates high pressure = the
evaporator pressure regulator or hot gas bypass valve or suction throttling
valve is defective or improperly adjusted.
If your A/C technician looks at you kind of funny when you mention these
indications or blows you off then find a different A/C service place.
Please let me know how this turns out. Like you in Atlanta, it gets
plenty hot here in Shreveport!! I'm using my A/C all the time already.
Rick Westerfield BMW CCA 75009
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