Only one thing that Gerry left out.
Did you connect a vacuum pump after you put the NEW receiver
drier in and a new expansion valve. Each time the compressor
quits all the cleaning has to be done and a solid vacuum pulled.
Living in Florida I run the pump for at least an hour just
because I have the time and it helps boil any moisture out of the
system. Then close the gauges off and see if the vacuum stays the
same after an additional hour. If so then you put the freon in.
If you didn't do the vacuum then there is air and moisture in
there and the new receiver drier is probably dead with moisture
right from the beginning.
archer75--- via Mercedes wrote:
Karl Wittnebel wrote:
Pressure goes super high, then the compressor fails. It will cool for about
30-40 minutes per compressor. Has new evaporator, new expansion valve new
drier, now on compressor #3 (or about to be). Control unit is new. At least
one new pressure hose. All the vac pods are new, as is the dash. Works
great for awhile, then gradually gets warmer over an hour or so, and that's
it.
Any ideas on how to troubleshoot this further? Tired of throwing
compressors at it. Nippodenso units from rock auto, same as original. Of
course the motor is a 606 now.
Thanks
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Has the AC auxiliary fan been coming on?
Did you disconnect all the lines and wash, then blow, them out using AC solvent
from NAPA or elsewhere in the opposite direction from their direction of flow?
Did you replace the main freon filter/reservoir?
Do you have a set of AC gauges (about $60 at HF)?. If so, what were the
readings when the AC was not working properly? (Carefully learn how the gauges
work so you don't accidentally send high pressure into low pressure cans of
freon and/or the low pressure gauges, which could be very injurious or fatal).
Which lubricant did you use when you replaced compressors, etc? Did you add the specified amount?
Did you add the freon with the can upright or inverted?
If you added the freon using the typical low pressure gauge that comes with some cans of freon, what was the pressure reading when you finished?
Did you have a household or shop fan blowing through the radiator and condenser
when you added the freon? Did you have the AC set on max cool and max fan speed?
What has the temperature been where you live?
There is supposed to an (add-on?) filter that can be installed in the return
line just before the compressor, but I've never heard any discussion about it
on this list, or have seen it listed anywhere. Also, I have no idea where it
would be installed without cutting the return line. This is supposed to keep
the shedded debris from old freon lines from getting in to the AC pump and
other parts.
Which car is this? All my experience has been with an '83 300D and '83 240D.
Most FLAPS have a book on auto AC repair which should give you the correct
amounts of freon and oil to add. The different types of oils should not be mixed
(see the book for a discussion of that.)
It's 2 am here in Florida. Later this AM someone with more knowledge than I
should be able to help you.
Good luck,
Gerry
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