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

["Marty Galbreath" <marty@xxxxxxxxxxxxxxxxx>]

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 compressor?  

Any advice appreciated.

At wits end,
Marty Galbreath
#3765

 

 









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