Another old Liebert unit I am raising from the dead. Its a 1994 Challenger 3 with Level 0 controls, Glycol.

Unit starts up and compressor comes on. Gauges show 60/205. Liquid line solenoid opens up, and the coil gets nice and cold.

After three minutes, the compressor shuts off. No alarms.

I was reading the manual, and compressor has positive start, so it always comes on for 3 minutes bypassing electronics, then after 3 minutes, the electronics take over.

The cooling control relay is definitely being activated to shut-off the compressor contactor, but I cant figure out why.

The sight glass does have air bubbles in it, so the unit needs a little charge. But I can't imagine why that would cause the compressor to shutoff. I have run newer Lieberts, and when they have a leak, the still run.

Other observations. This unit has a HP switch, but there is no LP switch of any kind - the only thermocouple on the low side is for the TXV. According to the manual that is OK for a glycol unit. I also tried manually overriding the electronics with the triac jumper (Q6 I think), but no luck.

Also when the compressor shuts off, the electronics still show it in cooling mode, and the liquid line solenoid is still activated.

I'm worried that maybe the unit has messed up electronics if charging it has no effect.

Any ideas?

Thanks
-John