RE: [DML] AC system compressor doesn't cycle, high discharge pressure
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RE: [DML] AC system compressor doesn't cycle, high discharge pressure

You may have TOO much freon in the system. The low side pressures should be
about 35-40  psi if I remember right. The compressor is always running
trying to pull the low side down.

Dave Sontos 

-----Original Message-----
From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On Behalf Of
Marty Galbreath
Sent: Thursday, August 11, 2005 1:00 PM
To: dmcnews@xxxxxxxxxxxxxxx
Subject: [DML] AC system compressor doesn't cycle, high discharge pressure

I am having a terrible problem with my AC system on the Delorean. 
Maybe someone can point me in the right direction.

The beginning.after I had my car restoration complete, I checked the Freon
charge and saw it was empty. I evacuated the system and charged with 36
ounces of R12. I had replaced the low pressure switch since it was old and
rusty, but nothing else was done to the system.

The compressor ran all of the time, pressure was way high on intake and and
about right on discharge. After a few minutes of driving, either the high
pressure switch would turn off the compressor or the evaporator froze up,
and the air got warm.  I detected a leak in the evaporator as well. OK now I
need to do some things to the system. 

So I replaced the evaporator, restored the insides of the case with new foam
and such, replaced the Orifice tube, accumulator, flushed the condenser and
hoses, drained the compressor of oil, installed 6 ounces of new mineral oil
into the compressor, put two more in the lines for a total of 8 now in the
system, and replaced the high pressure switch because it was old. I
evacuated the system to a level of 30" Hg for two hours using a 5 cfm HVAC
vacuum pump. I charged the system again with 36 ounces R12. Same result. I
have 50-
55 psi on the low side reading taken at the service ports. High side reads
about 195 - 220.

I noticed as I charged the Freon that the cycling seemed to be somewhat
normal when I only had one pound of Freon in the system. As I added more to
reach the specified level, the cycling became more and more constant. At all
times during charging the suction pressure was above normal.

The fans at the front are both working strong and in the correct direction.
The condenser is as clean as possible.

What would cause this high suction reading and continuous running of the

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