Fritzing and unfritzing the fridge

Yep, it was my fault. I had the fuses there, right there, lying on the batteries. I had the batteries disconnected, as I was checking to make sure (we got them second-hand, and we’ve had them 5 years) that one wasn’t pulling the others down. This needs separation, so you can measure the held voltage in each. I used a separate battery as a stand-in, running the house, and the fridge.

For some reason, I didn’t flip the knife-switch, or disconnect the fridge. Something zapped – I’m not sure even yet what. I heard the crack from the fridge electronics box (part of the compressor) and saw the smoke. Bother, said Pooh. Jennie and Zeb decided they had urgent business in the general direction of ‘away’.

I dug my way in (the fridge is built into the house) to the compressor, removed the circuit board. A component (unfamiliar size, but looking like a diode) was scorched, and fractured. A quick ring to the agent: no, they only sell the whole board, no fix. If the board is the only thing shot, it’s $400. If the compressor is shot, $1,100.

Ouch. I went up the drive to Jennie, and suggested she’d perhaps made a mistake in life-partner-choice. Then I drove to town, thinking. If the board had to be replaced, I had nothing to lose by trying to fix it. What does it do?  It takes 12 volts, positive and negative. It takes a thermostat, which is just a switch. and it drives the compressor. The plug to the compressor had three equally-placed pins, and could be plugged-in any way around. So, I surmised that it had to be a three-phase AC compressor motor, and the chances were that it would be 12 volt too.

I bought a diode (no numbers made sense, so I did it by size!) nipped back to Dad’s workshop, soldered it in. Put a 12 volt supply on the appropriate lugs. Put a clip-lead across the thermostat lugs. Selected AC on the multimeter, and tried the 3 pins. 8.9. 8.9. 8.9 volts AC, between them. Given that AC between poles measures where they cross over, not at the peak – that seemed good, as did the fact that they produced something, and the same something at that.

Shot home, buying a bag of ice in case. Connected it up, the lovely purr of the compressor. Watched the internal temp drop to 2.4 – its bottom number. Had a shiraz. Told my partner she had chosen wisely.

PS – There is now a fuse in the line.        🙂




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