Freezer repair (pop noise!)

[Part timer]

I have a Zanussi 2080 chest freezer (been retired to my garage last summer) which won't start when I plug it in at the wall. It makes a pop sound (the fluorescent lights dim momentarily), then tries again with another pop sound after about 10 seconds (I then turned it off to investigate further). Got the end panel off, as well as the control panel:

't worry about the insulation leak (brown) - that's original from the factory. Excuse my bricks under the corners - it helps me get hands underneath it to lift it. Control panel (demounted): (UK Mains, 170W): connections to the compressor: had a clip-on plastic cover over (which I removed to see what was going on inside. Every time it was plugged into the mains, I could see a component glow red (!) before the pop sound (it then cooled off). That was above the red component on the left (it wasn't glowing when the picture was taken).

Any ideas? Is it a simple fix or is it a goner? (My level of competance with a soldering iron & screwdriver is OK) but I won't touch refridgerant tubes etc. I won't kill myself with live mains (in case you were hesitating to help!)

Cheers.

[Clive Mitchell]

In message , Part timer writes

Compressor may have seized during storage. a gently whack with a firm but not sharp object may free it. Other than that it all gets a bit complicated.

[Andrew Gabriel]

I agree with Clive. Another possibility is that you moved it, didn't let it settle for 24 hours before switchon, and the expansion jet waxed up, causing the compressor to overheat and short out internally. I've managed to write off a freezer that way, although the 'moving' in that case included having it upside down IIRC, and even settling for 48 hours after that wasn't enough. (A Hotpoint engineer later advised me the way to avoid that is to switch it on for only 1 minute every 10 minutes for the first couple of hours.)

The gubbins on the side of the compressor are cutouts for overheating and overcurrent. Overcurrent cutout gets used quite a bit in many freezers in normal operation. The compressor has barely enough power to start in modern low energy freezers, and if the compressor output is still pressurised due to having run quite recently, the motor will stall and rely on the overcurrent cutout to protect it.

[Clive Mitchell]

In message , Andrew Gabriel writes

The coil bit may be a starter unit that initially powers a start winding if the main winding is drawing too much current (stationary). Never really done much with small compressors. Done lots with the big "car engine" sized industrial units though.

[r.bartlett]

Cheers

Richard

[Steve Walker]

Car engine sized isn't big! Try a compressor with an 8MW motor or a far larger gas turbine to drive it! ;)

Steve W

[Clive Mitchell]

In message , r.bartlett writes

No. They could generally run in both directions although not continually if the bearings had run-in, so a compressor seized in storage could occasionally be given a new lease of life by swapping the phases and giving it a quick jag. Alternatively the professional compressors could be stripped down like a car engine and the seals replaced. You can't do that with a hermetically sealed home-fridge compressor, so a soft thump is your only easy option before it goes to the "safe CFC disposal" site.

[Clive Mitchell]

In message , r.bartlett writes

Pumps and compressors are notorious for just "sticking" when stored. A gentle thump with the hope that it may transfer enough vibration over to make it stick just a bit less is an infinitely better choice than dumping it.

Of course, you could open the compressor with a huge tin-opener and give it a bit of a spin by hand..........

[Clive Mitchell]

In message , Steve Walker writes

800A per phase on 415 is still a big compressor bank.

[Steve Walker]

I grant you it's a fair size, but still the bottom end of the range for the company that I used to work for ten years ago!

Steve W

[Part timer]

Gentlemen! Enough of the size comparisons ;-) Anyway, the percussive maintenance I doled out to the compressor casing with a 2lb hammer didn't seem to do much good, just increased the time between the pops (when I stopped tapping, about 10 seconds later it would try starting up, glow and pop). A small tap say once every 6 seconds would keep it from even trying to start up. Is this any more of a clue before it gets disposed of? It's not costing us either way as it's already been replaced last summer with a highly efficient Bosch one (if that lasts as long as this Zanussi it will have done well).

Thanks for the replies.

[Clive Mitchell]

In message , Steve Walker writes

Oh yeah? Well mine were more aesthetically pleasing and you could stick one in the back of a van. (With lots of effort!) :)

[r.bartlett]

No it never does!!

The other way I've seen is to grab the compressor and rock it like mad -you can hear the motor knocking around inside- then trying it again...

That never works either!!!

Cheers

Richard

[Clive Mitchell]

In message , r.bartlett writes

I'm sure for one of the pot compressor types there IS a way to make it jolt in the wrong direction by some devious swapping of start winding coil connections, but it's probably best suited for those of a good technical disposition.

I remember reading a short article about the tendency to get stuck in this manner and some maintenance guy had built a little unit that allowed him to free them by jolting the rotor backwards electrically.