Thursday, August 16, 2012

Fixing Whirlpool Refridgerator

Found that some "click" noise heard inside kitchen since last night. Then find the fridge is not cold any more. The lamp inside lit up normally. A clamp ammeter is used to check the current through the compressor (actually 2 wires lead to the compressor relay box, which in turn is plugged to the side of the compressor with 3 pins). The lable at the back of the fridge noted 1.5A @ 220V. However, the ammeter reads 5 A for 2 seconds and then down to 0A. A "click" noise is heard just before the cut out and this is assumed from the thermo protector in the relay box. What in my mind is that the compressor is seized as it does not run up at all. I make this guess as I found grease over the high pressure lines.
Then I read the net and found the relay box is the commonest fault. Then I go back and check
1) Voltage at the relay side : 3 pins -common, Run and start. The start/common pin reads erratic 180V-200V only , when the fridge is switched on.  This makes me suspicious.
2) Check resistance of the 3 pins on the compressor and looks for 2 coils Ohm reading. The sum of the smallest 2 reading should equal the highest value. Make sure the pins are not ground as well. My readings are 10 Ohm, 6 Ohm and 16 Ohm. So I suppose that the coil is not dead.

The relay is then suspected to be faulty. On opening up the relay box, I found chips of broken ceramic disc (later I found this is the so called PTC relay, or labelled as PTC thermistor from the fridge offical circuit label. This ceramic disc is shattered that the 2 pins (run and start ) lost their connection at the spring contact. The largest piece of the ceramic is realigned such that the 2 pin contact on both sides of the disc. Contacts are sanded and sprayed.

Then I pray and switch the fridge again. Wow.. the compressor works again !


The above is the compressor relay, which is usually found on the side of the compressor with 3 pin socket. The ceramic disc is found shattered. This PTC thermistor works by channeling current to the "starter" coil in first second. Temperature/resistance increases and current goes through the "run" coil circuit then.
Largest remnant is placed over the contact pins as a temporary measure, till I found a replacement part.