ZISP420DXASS GE Monogram Refrigerator not cooling

[mjordan29]

Model Number

ZISP420DXASS

Brand

GE

Age

More than 10 years

Hey All,

GE monogram not cooling. It is one with the compressor above the refrigerator, not below. I lost freezer and refrigerator cooling. The evaporator and condenser fans are both working. Having a hard time telling if the compressor is on. Resistance from pin to pin for the compressor is ~7 ohms from pins 1-2, 1-3 and 2-3 so that seems reasonable. With the inverter unplugged from the compressor the inverter is outputting ~100Vrms on each channel relative to safety ground @ 60hz.

If I plug the inverter into the compressor I get slight voltage adjustments (couple volts only) and freq is always locked at 60hz. Each of the three output pins is in phase with the others (not sure if that is correct so figured I'd mention) and each waveform although it read 100Vrms is actually a couple volts positive peak and maybe 175V negative peak....

Just weird, not what I expected to see on the scope but I haven't found anyone documenting what the waveform should look like. Control wire to inverter when unplugged is about 11.5V. Condenser coils are dusty but it was working fine for the last few years and then all of a sudden not. I would expect dust to degrade performance slowly... I'll clean them but they are hard to get to so it wasn't my first priority.

What should I check next while I have the whole darn refrigerator torn apart? Think it is the compressor? Refrigerant problem?

Thanks,
Jordan

 

[Jake]

Hi Jordan, After the refrigerator is plugged in, the inverter will attempt to start the compressor with in 8 seconds.

When checking inverter voltage output, connect the test-meter leads to any 2 of the 3 compressor lead wires at the inverter plug (plug should be connected). The same reading should be measured between any 2 of the 3 wires. The inverter controls compressor speed by frequency variation and by Pulse Width Modulation (PWM). Changing frequency and PWM will cause an effective voltage between 80 and 230 VAC to be received at the compressor.

The inverter receives commands from the main control board. The main control board will send a PWM run signal from the J15 connector of between 3-6 VDC effective voltage to the inverter (all wires must be connected). The inverter will select compressor speed (voltage output) based on this signal.

The main control board will only send a run signal to the inverter when the compressor should be on.

Note: When measuring signal voltage (from the main control board) at the inverter, a reading of 3-6 VDC will be measured with all wires connected.
The inverter will monitor compressor operation and if the compressor fails to start or excessive current draw (4 amps maximum) is detected, the inverter will briefly stop voltage output. The inverter will then make 12 consecutive compressor start attempts (once every 12 seconds). After 12 attempts, if the compressor has not started, an 8-minute count will initiate. After the 8-minute count, the inverter will attempt to start the compressor again. If the compressor starts, normal operation will resume. If the compressor fails to start, this process will be repeated. Removing power to the unit will reset the inverter count. When power is restored, the inverter will attempt to start the compressor within 8 seconds.

Here's the inverter board for your model:
GE WR49X10283 Inverter W/jumpers Kit


Here's the motherboard for your model:
Main Control Board Assembly WR55X11070


Let us know what you find.

Jake

 

[Jake]

Also, if the fans are running BUT compressor is NOT running at all--->You may have a bad compressor inverter board, sometimes you can tell from just looking at the compressor inverter board if its bad or not, unplug the refrigerator and look for burnt components on the compressor inverter board.

If you DON'T see any burnt components on the compressor inverter board, you'll need a multimeter to check volts.

Check for 3-6 VOLTS DC between the two smaller wires going to the inverter. Then check for 120 VOLTS AC between the orange wire and the black wire going to the inverter. If the voltage is correct, remove the inverter from the compressor and measure the resistance of the compressor windings. You should have about 10 ohms between any two pins.

Jake

 

[mjordan29]

5.26 Vdc on the control signal.

0V AC between compressor pins with inverter connected.... about 1V when it is trying at the 8sec intervals. So i guess that answers the question about if the scope waveform was correct (it didn't look like what I would expect). I'll put an inverter board on order... Hopefully that is all it is.

 

[Jake]

Did you check for 120 volts AC on the larger wires going to the inverter?

Look here:

PFE29PSDASS GE Refrigerator not cooling at all | ApplianceBlog

Jake