Wine fridge

For my Facebook friends, this is a repost. Too bad.

I had been putting off fixing a broken wine fridge a buddy gave me for ages, because I thought it was the leaked refrigerant problem, which is a tedious pain to fix.

 

I finally decided to just get it done, so it's one less thing to deal with. I plugged it in to do the prechecks to make sure the compressor is running, to find its not starting, just buzzing. Hmm.

 

I unmounted the compressor, there's just 4 nuts, on top of washers on bolts which go through the rubber vibration mounts, and started to pull the compressor out, but quite quickly realised that the wires weren't long enough for me to go very far..

 

So after pulling the wiring apart, which looks like this:

(Yes, I noticed the insulation on the wire had cracked and the bare wire was exposed. It's just the neutral anyway).

I was then able to move the compressor out properly, and I then noticed that the brown connector on the side was rattling. That's suspicious..

 

It was also strange that there were only 2 wires going to the compressor, since they need a third wire to start them.

 

After I squeezed the clips on the side of the rattling connector, allowing me to take it apart, I immediately realised the problem, when this happened:

 

Dodgy wiring documentation underneath. It's unlikely I won't be able to work out how to reconnect 4 wires, which are colour coded, but just in case..

 

Well. There's your problem!

 

I had fixed this exact issue before on a different fridge that I rescued from going in the garbage, from the office I used to work in.. 

 

If it's not immediately obvious what the problem is, there aren't supposed to be all those "bits".

 

This design uses a PTC, which is a thermal resistor, or thermistor, in order to provide the third connection to the compressor, for the starter. This resistor is implemented as a small disc of material, which seems like ceramic. (Apparently it's something covered with silicone?)

 

The way these work is that when they are cold, they have very low resistance, so current can easily flow through it, to provide the offset to the extra winding on the motor, in order to kick start it, similar to a starter motor on an engine.

 

Very quickly this causes the disc to get hot, caused by the current flowing through it, which increases the resistance, so it basically removes itself from the circuit, disconnecting the starter winding, which isn't needed once the motor has started.

The problem that occurred here, and in the other fridge, is that the disc breaks, possibly from expanding and contracting every time it's used? so then there's no connection to the extra winding to start the motor any more.

 

Just to make sure that this is actually the problem (I'm almost certain it's going to be), I do the equivalent of what the PTC would do.

 

I do this by hooking up an extra wire to the third connection, the starter winding. I then take the AC supply cord, and disconnect it from the rest of the fridge, or use a separate/spare AC cord.

I then hook the AC supply cord directly up to the common (active) and the run (neutral) terminals on the compressor.

 

When I first power up the compressor, which I do by plugging the cord into the AC supply, I just (VERY CAREFULLY) touch this wire from the starter winding to the neutral (run) connection for a half a second. ie I short together the 2 terminals on the compressor which would normally have the PTC disc held between them.

 

This confirms that the motor will start and run. I also leave it running for a few minutes, just to make sure that the compressor sounds happy, and that it's causing one of the copper lines coming out of it (the high pressure line) to get hot, as this means that the system has (some) refrigerant in it, so it's likely that the whole system will actually work.

My "proper" fix, so that I don't have to kick start the compressor with the extra wire manually each time it needs to cycle on, is to find a couple of the biggest broken pieces of the disc:

 

 

 

and wedge them back in between the contacts in the holder/connector, and it's fixed.

 

It may (will?) fail again eventually, for the same reason it failed in the first place, but it's only a couple of minutes, if that, of work to replace it.

 

You literally just need to pull the neutral wire off the run terminal, and then the PTC housing/connector off the compressor, squeeze the clips, open it, insert the new disc, close it back up, press it back on the compressor, and then put the neutral wire back on the run terminal.

 

Maybe I should buy some spare PTC discs instead of recycling the broken pieces..

Anyway, with that done.. I patched up the couple of places where the insulation had dried out and become brittle and cracked, by cutting off the ends, and re-terminating the wires, and taping them all up.

 

I had also undone the wiring from the terminal block which goes inside to the thermostat/fan/lights etc, in order to clean all the terminals and connectors, but this wasn't really necessary, I just figure that since I'm already in there, I might as well make sure nothing else is dodgy or about to fail..

 

I remounted the compressor back inside the unit, the bolts just go up through the bottom of the fridge, and through the rubber anti vibration mounts, there's a metal spacer which goes over the bolt, inside the mount, and then the washer and bolt go back on the top.

 

The back left nut was a pain in the arse to get back on though. I suspect having tiny asian hands would make it a lot easier than someone like me trying to get their paws in there..

 

So then with it all wired back together, I plugged it in to test, and what do you know? The compressor started straight up, and nothing even exploded or caught on fire. Boring.

 

It was quickly able to get the internal temperature down to the set level, and then the compressor clicked off, and it cycles back on whenever the temperature goes back up..

 

It's been sitting on the bench for a few days now, and I have power cycled it a few times, with hours in between, to make sure that it always starts up properly, and can get down to temperature.

 

It works perfectly. Too bad I don't have any bottles of wine to put in it. Anyone need a wine fridge?