Electrical or gas problem with my freezer. What do you think?

[Bungarra_Bob]

Hi all,

I'm so-so with the electrical side but a total n00b with the gas side.

The freezer is an upright 340litre, Westinghouse FJ383Q-R. It uses R134a (126g).

Until recently it was working fine except for a mechanical rattling/buzzing noise when the compressor was on.

When we noticed it was not working properly, the “ALARM” light on the bottom was lit and the evaporator fan was off. The food was still cold apart from the top shelf and when the freezer was emptied, all the evaporator coils still appeared cold.

The compressor was very hot. It appeared to be cycling on its internal thermal cut-out.
My original assumption was that the evaporator fan was blown. I removed it and it tested fine. Ie. It is *not* the evaporator fan.

My next assumption was that the defrost heater shared the same circuit as the evaporator fan and it was *that* which had blown. I tested it and the problem is *not* the defrost heater element. It has a resistance of 133.7 Ohms (equates to 430 Watts) and matches the specification.

I next tested the defrost limit switch (terminator thermostat). I cooled it in a different freezer to below zero and it records 0 Ohms (short-circuit) when cold. When it thaws, it records 200K Ohms to 300K Ohms. Frankly I would have expected a complete open circuit but that is certainly enough to shut down the defrost heater.

After checking the fan, defrost heater and defrost limit switch, I let the unit run for a little while. The bottom two folds of the evaporator coil cools nicely. These are the closest to the compressor feed-in. The remainder of the evaporator coil does not cool substantially.
Ie. The bottom of my evaporator unit gets cold, the top does not.

I am now thinking that the non-functioning evaporator fan was a red herring. Could the ALARM be caused by low R134a pressure?

Now that I have run the unit while open, it would seem like the previously described rattle is the evaporator coils vibrating. Maybe this rattled a slow leak into the system? That eventually tripped some low pressure alarm which shut off the evaporator fan and effectively killed the unit’s ability to work at all? Is this possible?

Thoughts? Suggestions? Advice? Jokes? Sympathy?

[Tesla]

Guiday Bungarra Bob and welcome to the forum
Indeed you have a bung fridge. Sounds like short of gas. Look for corrosion or oil on any welds, but you will need to leak test with a sensitive electronic (soapy water might not do) detector and check the gas side pressures if you have the tools.

[tonto33]

It's a system fault could be a blockage or just short of gas, if got the equipment stick gauges on and find out if not call in a pro