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AlexM

G.E. Fridge SxS Model# PSH23PGPGTAWV, Tired of guessing.

16 posts in this topic

About 5 months ago I replaced all (3) thermisors and that seemed to fix the vague tempurature variations.  This week the customer called back with more tempurature swings, mostly getting warm in fresh food and freezer section.  This is what I did yesterday.  Checked the mother board for physical damage on the back and any relays that may have looked bad, all good.  Cleaned the condensor. The compressor and condensor fan seemed to be working.  I opened up the evaporator area and replaced the defrost heater and limit, the evaporator was only icy near the top and it didn't take much to defrost it.  The reason i replaced the heater is because the glass was broke on one end and it was all gray and cloudy inside the tube. 

 

The customer called back 24 hours after my latest repair and still having temp issues.  My suspision is that its a evaporator fan issue.  Finally I will ask my question:  Is there a 'cheat sheet' that someone might have that gives the various circuits and values to be looking for so I can stop guessing? 

 

Also, if I determine that it needs a new evap fan, should I get a new board at the same time?

 

Also, the board on one of my websites says it would be P/N WR49X10152 but there is a sticker on the back of the fridge that says to replace the board with P/N WR55X10156,  I should go with the one printed on the fridge?  I believe this is a variable speed compressor unit.

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Need appliance parts? Call 877-803-7957 now!

... the evaporator was only icy near the top

may have a Sealed System leak ..

may need to see pictures of the Freezer Evaporator

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This unit has a custom cool compartment and so has four thermistors. The most troublesome one is the one attached to the evaporator because it sees 100F temperature swings and gets lots of moisture exposure. It controls the defrost cycle. Very common for it to go out of calibration and mess up the defrost cycle, usually making it too short and causing the evap to ice up and making the beer compartment intermittently warm. Most Appliantologists, unaware of how critical and vulnerable this thermistor is, overlook it and replace the other thermistors to no avail.

I've gotten to where I just replace these evaporator thermistors as just part of SOP of servicing the unit anytime I'm in the freezer of a GE refrigerator. It's kinda like replacing the bimetallic on the old-style units anytime you replace the defrost heater or evap fan. Same deal here.

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So, when I was in there the other day I did check that I had changed the thermistor on the evaporator.  The frost pattern looked to me excactly like what you discribed, that the heater isn't staying on long enough.  I checked my connections and they seemed good. Could that new thermistor be bad after 5 months?

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I have a confession, I used butt connectors for the thermistor splice and can't remember if I used silicone,  should I be using bell connectors?  and would soldering with heat shrink  be acceptable or recommended when splicing thermistors?

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... the evaporator was only icy near the top

may have a Sealed System leak ..

may need to see pictures of the Freezer Evaporator

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I have a confession, I used butt connectors for the thermistor splice and can't remember if I used silicone, should I be using bell connectors? and would soldering with heat shrink be acceptable or recommended when splicing thermistors?

Three years ago, Samsung was saying that their sensors needed to be soldered in. GE had no real guidance on it so I defaulted to Samsung's guidance because its all the same technology. Then about a year ago, GE came out and clearly said that bell crimp connectors are acceptable IF and only if you seal the open ends of the connector with RTV silicone. GE makes a food grade RTV, don't have the model number right now, but it's what I use.

Butt connectors are a big no-no. Unsealed butt connectors are a big Bozo No-No. Those connections will corrode and add resistance to the sensor circuit. These are NTC sensors so as resistance increases, they will falsely report a lower temperature to the muthaboard causing the poor temperature control. In the specific case of the evap thermistor, it will cause premature termination of the defrost cycle causing incomplete defrosts.

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The butt connectors I used sounds like the smoking gun, glad I asked and glad you knew the answer!  Thanks So Much!

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Measure the voltage drop across the evap thermistor and then, quickly get a pin point accurate temperature shoot with your IR gun on the evap thermistor itself. Compare this voltage reading with the voltage-resistance-temperature chart for the thermistors found in the service manual for this model. Service manual should be in the Downloads section. If the voltage drop is higher than it should be at the measured temperature, then you know the problem is in that evap thermistor circuit. If the voltage drop is within spec, then we may be dealing with a sealed system problem, a damper problem, or something else.

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I didn't get your last post until I got home tonight.  I didn't test the circuit at the board, but did put a new thermistor on, properly.  I brought the old one home to test in ice water.  I'm getting used to analog meter so I tested with my digital meter as well, they both showed 16k ohms before I cut off the butt connectors and after.  Would this indicate another issue since it tested good?

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The sensor itself was only one of the variables in that circuit, the other being the unsealed butt connector splices. With the sensor cut out of the circuit and being tested, we have no way of knowing whether the splices were the problem or not.

With the new sensor properly installed, now we go to the Big 10 Steps for Solving No-Cool Complaints:

1. Check for loose plug at outlet, intermittent power

2. Check door seals, esp., bottom corner rot and hinge side pucker

3. Check integrity and continuity of 12vdc harnesses

4. Check door lights and switches for proper operation (light staying on)

5. Check condenser for lint build up.

6. Make sure both fans, evap and cond, are running

7. Check for excessive frost in the freezer or abnormal frost pattern on evaporator

8. Check proper defrost operation

9. Check compressor operation, including current draw and megger check on windings

10. Do the diagnostic self test on the main board

That's the riot act for solving no-cold complaints. Doesn't matter which order you do them in. But this will identify the problem.

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I didn't see any mention of using the built in diagnostics to run the thermistor tests. They all showed 'P'?

 

I tried to check to be sure that your interface has the display but the model number in the title of the thread is wrong. The closest one I found was a   PSH23PGTAWV

 

Is that your am-nimal?

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Yes my mistake on the correct model #, you were correct: Model# PSH23PGTAWV 

 

I replaced the mother board based on the following test: I set my meter to read DC voltage and placed the black lead on J2-pin 3 and my red lead on J2-pin 5 and got about 7.5vdc and a read somewhere that if it is a variable speed compressor you should only read 4vdc, if not, replace the board. 

 

I did replace the board and tested the same pins, I got the same 7.5vdc.  which is above what I thought it was supposed to be.  Do you think I fixed it with a new mother board?

 

thanks,

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... the evaporator was only icy near the top

may have a Sealed System leak ..

may need to see pictures of the Freezer Evaporator

.Note: When measuring signal voltage (from the main control board) at the inverter,

a reading of 4-6 VDC will be measured with all wires connected.

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ah for the days before digital.  control strategy was really digital back then (except analog timer) , it was just 120V digital 1 or 0.  that kind of voltage didin't give you so much trouble over how you attached your thermal sensors - other than that you insulated them well.

 

i've always hated butt connectors other than solder and heat shrinking so I always used wire nuts carefully taped. get the RTV silicone approach.

 

but this sounds really frustrating that you are getting wrong voltages off new board and old board.  still don't know if it is really fixed.

 

a lot of stuff can be electrical but with all this circutry crap being add to these new units, couldn't somebody come up with a reliable pressure indicator for the high and low side for a quick indication of cooling system operation.

 

the one thing that occurs to me is whether the odd frost pattern on the evaporator actually indicates a coolant problem rather than a defrost cycle problem.

 

how old is this fridge?  the one downside of pressure indicators or other service access to the refrigerant circuit is that these are usually pretty bombproof for maybe a 20 year life and adding complexity and access can actually be the source of the leak.  although as the master appliantologist has pointed out, you might not get the right pressures not because of a loss of refrigerant but because of dirt/dust clog on condensor, blockage of flow or intermittant or unreliable operation of fans etc. My inquiring mind wishes that every refrigerating appliance in the world had onboard gauges. and in the IC age, there would be nothing to stop them charting the operating pressures and saving snapshots every ,month or so so you could track operation before and after cleaning and over a period that might quickly indicate problems, coolant loss, etc.  -- all of this balanced by the problem that coolant control and measurement is unfortunately one of the most likely sources of coolant leaking. when you come up with a refrigerant that has the pressure and physical characteristics to reduce that phenomenon, then you've really got something.  because refrigeration is civilization - thus refrigeration repairmen are the centurions of the day -- albeit given our nature we might more -- as I often do -- claim the mantle of archibald tuttle. i.e. the DeNiro character from the movie Brazil.

 

appreciate being a fly on the wall for this headache because it helps me know I'm not the only one who faces seemingly insurmountable diagnostic issues with these IC refrigerators. 

 

one issue I have is that the GE I last had a part, there was no test facility that I could find for the defrost cycle, so you just had to infer it was busted from symptoms, rather than test it, and you pretty much just replaced all the parts.  Maybe this is the wave of the future but my clincal mind gets clincally depressed contemplating it.

 

time to go off and crack an IPA before noon when I run into this stuff.  let us know if you need to bailed out of the drunk tank.

 

brian

Edited by occidental tourist

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I don't know how old this fridge is, and I have a temporary break from this unit, as the owner is out of town.  I will find out anyday if the unit is working or not.  Thanks for the input, much appriciated!

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