I got called to a customer last Friday as his cold room was no longer cooling.

He said that the fire brigade had broken-in in the early morning and tripped the whole place out due to an alert from a neighbour of smoke coming from within. Nothing to do with the cooler though.

On arrival and after resetting the main trip switch they found that the cold room comp wasn't running.

When I got there I found the contact relay (KM1) was energized but 0V across the three phases. I found the trip switch before this was out so I tried to reset it but it wouldn't have it. After disconnecting the comp the trip switch stayed in, and I was getting 400V across the disconnected wires. So, after checking windings' resistances concluded: comp change.

Got the comp in the morning and changed it out in the afternoon. Now he waits until I've finished (chopping, modifying, brazing, pressure testing, fixing leak, re-pressure testing, vacuuming, charging) to tell me that this is the third time in three years!

So, after I got it up and running a gain I start gathering info to try and work-out the cause.

Calculation for room 2759W
Condensing unit unité TAJ4519ZHR 404A 2771W@ -5°C
Evap Friga Bohn MUC420 4600W

Seeing this mismatch I go back and find the TXV is a TEX2 R22.

Before filling in the details on the comp autopsy, running temps and so on I wonder if anyone has anything to say about this set up and the life span of the compressors?