I have an air cooled Isotherm
unit with ASU (auto start up) charging
a holding plate in cool box. The compressor
is a single
Having spent $500 on servicing including replacing line couplings, condenser etc. I was disappointed that after only a month or so it failed again.
Now when I switch it on the compressor
starts briefly but stops after between 10 seconds & 20 minutes. The lights on control panel
indicate compressor overload. Checking refrigerant (R134a) pressure (low side) shows 25-30 psi with compressor off, dropping to 15 psi when it runs. It makes no difference if I try to run it in Manual or Auto (voltage sensing) mode.
Removing refrigerant (lowering pressure) allows compressor to run longer but it always shudders to a halt after a while suggesting a heavy load. The compressor gets quite warm but the high pressure line to condenser seems cool & no sign of cooling
on cold plate at any time.
Trying different pressures (adding/removing gas) always gives similar result. If too high when running (> 18 psi) compressor stops after a few seconds & although it tries to restart this fails. If low (<= 15 psi) compressor will run for up to 30 minutes before stopping but it gets quite hot with no sign of cooling
. Whilst running it never goes into high speed mode despite being on shore power
& cycling battery charger
into mass mode with approx 13.5 volts at control unit.
I am fairly sure there is no air in lines as they were vacuumed after last repair & I have been very careful purging re-charge lines before adding refrigerant. Also there are no signs of leaks
. Have also checked & re-made all electrical
Any help or suggestions would be appreciated.