Kenmore 795.79002901 compressor not running

Mike7987

Member
Joined
Jun 20, 2019
Messages
4
Location
USA
Model Number
795.79002901
Brand
Sears Kenmore
Age
6-10 years
Symptoms:
- compressor never runs
- evapo fan struggles to spin for about 2 seconds then spins ok for 8-10 seconds, then stops for 8-10 seconds, then repeats this pattern
- cooling fan runs
- starter relay makes a click
- after a minute code 67 comes on the temp panel
- running ok since 2011

Visual inspection inside:
- there is a dent on the compressor, must have been there all this time
- black pieces of what seems like rubber under the heating coils
- heating coils never cleaned, have some dust
- no burn spots on PCB

What I replaced:
- starter relay
- overload protector

What I tested:
- there is continuity on the starter relay and overload protector
- the 3 pins on the compressor have normal low ohms
- there is no short on compressor case to any pin
- there is 120 v on the starter relay wires
- the pins (4 & 6) on the PCB for the evapo fan have 12dcv
- ran diagnostic test mode- same symptoms
- the capacitor seems ok with mutlimeter ohm (numbers go up or down)
- tapped compressor with rubber hammer (didn't work)


Service manual says code 67 (light 6 and 7) is:
Failure of BLDC fan motor at freezing compartment ,
If there is no fan motor signal, for more than 65s. In operation fan motor
Poor motor, hocking to wires of fan, contact of structures to fan, snapping or short lead


With the code 67 pointing to the freezer motor, and seeing that it struggles to start spinning, then stops for 10 secs. Do you think replacing the evapo motor will get the compressor to come on? I thought the compressor is suppose to come on first, then the evapo motor? Says that in the service manual

Advice? thanks
 
Last edited:

rickgburton

Appliance Tech - Moderator
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Messages
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It sounds like you have two separate problems.

Mike7987 said:
.....spins ok for 8-10 seconds, then stops for 8-10 seconds,......pins (4 & 6) on the PCB for the evapo fan have 12dcv
If the voltage remains constant the evaporator fan motor is bad. However, you might not be measuring the voltage on the correct pins. The evaporator fan motor voltage is measured at CON4-Pin 5 to CON4-Pin 6. The voltage should be between 10 to 14 VDC when the fan should be running and 2 VDC or less when it should not be running.

Mike7987 said:
the 3 pins on the compressor have normal low ohms ......there is 120 v on the starter relay wires
A lot of the information LG puts in their service manuals borders on fiction. That's one of my major peeves with LG and Samsung. For example, LG states if the resistance of the compressor windings is between 1Ω - 50Ω the compressor is good. That's false. It's 1-5 ohms for the run windings and 3-11 ohms for the start windings. LG calls it a start capacitor. That's false, it's a run capacitor and a compressor doesn't need a run capacitor to operate correctly. Here's how to check the compressor:
43701


On your relay the resistance should be about 6.8Ω. The overload should be <1Ω. The evaporator fan motor doesn't affect the compressor operation. The overload will open if the compressor gets too hot or if draws too many amps. If the voltage at the relay and overload is 120 VAC and the compressor doesn't run, bad compressor.
 

Mike7987

Member
Joined
Jun 20, 2019
Messages
4
Location
USA
Thanks for the quick reply.

Here's what I got:

CON4-Pin 5 to CON4-Pin 6:
when connector is off: steady 16vdc
when connector is on: changes from 12 to 0.5 vdc every 10 seconds

What does this indicate what's bad? If it's 16 steady with no motor fan load, then 0.5 to 12 when it's connected?
Bad evapo motor fan or pcb?

On the compressor:
COMMON AND START: 4.1 Ohm
COMMON AND RUN: fluxes from 6.5 to 7.5

C&R is above the 5ohm. Is it bad?

Overload: 0.8
Relay: 7.6 (also above your 6.8)

What do you think?
 

rickgburton

Appliance Tech - Moderator
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Replace the fan motor:


Mike7987 said:
C&R is above the 5ohm. Is it bad?
Yes sir! Forget about the fan motor. That's the least of your worries. The compressor is bad. It's a very expensive repair that I wouldn't recommend on an LG machine.

I forgot to add the overload and relay are good.
 

rickgburton

Appliance Tech - Moderator
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Messages
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Anything but LG. No manufacturer makes a perfect refrigerator. They all eventually need some kind of service/repair. Before you purchase another machine, do your homework.
 

Mike7987

Member
Joined
Jun 20, 2019
Messages
4
Location
USA
Update. I hard wired the compressor and it runs. I have to hold the momentary switch at least 1 second, sometimes two.

I then attached just the overload (measured at 0.8ohm) to the compressor with the hard wired setup. The compressor starts and within 10 sec the overload clicks and shuts it off. After it cools down in a minute it clicks again (I guess it's resetting)

I have three overloads that all do the same. However when I shake them they all have a rattle noise. youtube posts say the rattle means the overload is bad and need replacing?

I know you said the compressor is out of proper working specs with the C&S above 5. Is the compressor destroying the overloads and that's why they rattle? So a bad compressor can still run but overheat? Also, it never runs when connected to the internal wires, only hard wired.

So I'm a bit confused.
 

rickgburton

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This is the compressor thermal overload. It connects to the common pin on the compressor. If the overload gets too hot or if the compressor tries to draws too many amps it will open. It's a safety device designed to protect the compressor.
43725


This is the solid state relay. When the compressor circuit is first energized the relay has low resistance, 3-12 Ω Both Start and Run windings are energized to start the compressor. The run capacitor is bypassed by the relay. When the self heating solid state relay has reached temperature it changes from a low resistance to a high resistance, 10KΩ to 20KΩ and switches off the start windings. The only purpose of the run capacitor is to improve compressor operating efficiency and not necessary for the compressor to run properly.
43726


This is the Start device. The overload and relay are combined in one unit. About ten years ago there was a recall on 1.7 million refrigerators due to an electrical failure in the relay. The internal contact points burned off and would jamb in the relay. This was a common service call. An easy way to test it was to shake it and if you could hear the contact points rattling around inside the start device was bad. Sometimes when shaking it the burned contact points and burned little plastic pieces would fall out. Not unlike a pepper shaker. This is the only part you can test by shaking it. You have a PTC relay/overload not a start device.
43727
 
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