high head pressure

[cribbetr]

HELP!! I evacuated a semi hermetic compressor with R12 as I put the r12 back in the system the head pressure will go 300 to 400psi and trip the pressure switch. what is going on ?

[t527ed]

discharge valve on compressor closed???? if not that something very very very bad to get those pressures with r-12

[onetime]

It sure sounds like a valve on the high side is closed or a blockage, bad txv.

[LGM]

You either had non-condensibles or added them by mistake, most likely. Easy way to check:
- Close liquid line solenoid and let the system pump down.
- Remove a control wire from the compressor contactor.
- Jump out the condenser fan and let run for 1/2 hour.
- Get high side pressure.
- Get ambient temperature.
- Look at P/T chart for the ambient temperature measured. If the pressure is more than a pound or two higher than what it should be (which allows for the gauge to be off a little), you have non-condensibles.

Hope this help.

[Makinice]

What was the reason for the "evacuation"??
Did you change a system part or something?

[R12rules]

Back seat your discharge service valve stem and attach your hi side gage to the liquid line at the receiver.


THEN and only THEN ... restart your compressor.

[bob1420]

overcharged

[cphc]

overcharge or restriction on high side of system.

[dnt]

Have you checked water/airflow whichever applies over the condensor coil?

[Edited by dnt on 07-12-2005 at 03:35 PM]