Refrigerator - freezer defrost test

Hi All,

Fridge - Kenmore/GE 12 years old. Freezer on top.

My fridge was acting strange temp-wise, so I pulled the panel in the freezer and found the coil all frosted up. Defrosted it.

Now to the problem, as to why it happened. Pulled the defrost timer and found one crimped wire a bit loose. Soldered it. Did continuity test on the defrost heater - OK. The defrost thermostat contact was open, which was at 60deg - OK too. Put it all back together. Fridge works, but...

After about a 24hr run, I'd like to verify that the defrost works. The timer motor is turning, I can see that with the control cover off. But can I really tell if the defrost heater is working? Should the back panel in the freezer be warmer? This would verify the whole ckt.

RichK

Reply to
RichK
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A clamp-on ammeter on the switched lead from the defrost timer to the heater ought to tell you.

HTH,

Jeff

Reply to
Jeff Wisnia

Of course, the defrost lead will only be drawing amperage if the bimetal is cold enough. But, that confuses things.

Reply to
Stormin Mormon

"Stormin Mormon"

I have thought about the clamp on meter, after I posted it. Tried to feel the plastic cover in the freezer, but it's not good enough indication. It seems that the bottom of the back panel is a bit warmer, which is where the heater is.

Why do you say that it confues things? It seems like the only good test, I can think of.

Rich

Reply to
RichK

It *should* work, particularly if you have one of the motor driven defrost timers which has a manual knob on it which allows you to advance the timer by hand so that you don't have to stay there for a day watching the meter waiting for the defrost time to come up. .

I suppose if you were anal enough about it you could use a slow speed chart recorder to plot the output from a current transformer placed on that lead to see that current comes on periodically and stays on until the thermostat ("bimetal") senses that the evaporator area isn't ice cold anymore and opens the circuit.

Jeff (Don't take me seriously please.)

Reply to
Jeff Wisnia

"Jeff Wisnia"

There are some clear advantages to old tech designgs. The timer can be advanced using a screwdriver to rotate the cam operating the contacts.

No I did not take this part seriously :-) Don't have a chart recorder :-) But was going to ask, if anyone has seen something in that line. I'd like to record somehow, the total time an appliance runs in 24hrs - say the refrigerator in question. Of course you can sit through several cycles with a stopwatch and record the times.

Rich

Reply to
RichK

They are easy to check out. If it is your fridge, let it run a few hours and while the fridge is running advance the timer until it clicks into defrost mode. The evaporator fan should stop, wait a few minutes and open the freezer door and feel where the heater coil is located, it should be warm. You will usually get a clear indication that the element is heating.

If it isn't heating immediately unplug the fridge and check for continuity through the defrost termination thermostat circuit, it should be closed, if not and all the other circuits test okay, replace the defrost TH with one of the same termination temp. Check out the wiring diagram and schematic for check points.

- udarrell

Reply to
udarrell

There's an easy way to do that if you can get across the main load, like the compressor motor in a fridge.

Just wire an old fashioned electric clock across it, the kind with a synchronous motor. Set the clock's hands at midnite and.....You can figger out the rest...

Happy Holidays,

Jeff

Reply to
Jeff Wisnia

"udarrell"

You are right. The key here is to feel the heater area, soon after you force the defrost cycle. I could feel that part of the of panel warmer in the freezer. I also measured the current - it was 4A.

Left the defrost cycle on for a while and the thermostat must have worked, as the panel got cool again. I probably would have cycled ON/OFF during the

40min (spec) that the cycle runs.

I later measured the run current of the compressor in the same place in a circuit (a common leg) and to my surprise it was only 2A. Is this about right?

The compressor spec (from sheet on the back of fridge) is 1092 BTU/hr. Monthly energy consumption listed at 80 KWH.with 20-30% run time at 70F.

Rich

Reply to
RichK

Doesn't this thing have slide on connectors? Why not putting the ammeter right in the circuit? Most people don't have a clamp-on.

Remove NOPSAM to email me. Please let me know if you have posted also.

Reply to
mm

Actually, you're right. There's a connector that plugs onto the timer and another one near the Temp Control. Could have allowed the freezer to cool and close the defrost thermo, then checked continuity of the whole ckt downstream from that plug.

As it is, I had a clamp-on attachment for a multimeter and this was an excuse to use it. Also made me aware how much current is used.

Rich

Reply to
RichK

This is Turtle.

first the 40 minute cycle you speak of is new to me for the longest defrost cycle time that i have ever hear of is the 31 minute every 8 hours , but most are the 25 minute every 6 hours.

now if the defrost circuit is pulling 4 amps in defrost cycle. it is running and pulling the right amps. if it is pulling 4 amps your heater is running. Your good there.

most Refrigerator these days will pull 1.5 amps to 3.5 amps and most regular refrigerator will pull between 1.5 and 2.5 amps. So your 2 amps seem just about right.

now in your other post you spoke of a loose spade connection and not a broken connection. Was this connection broken enough to say it could break the power to that section or not ? we are looking for a cause for the defrost system to stop and have not found one yet. So now your going to have to watch it and try to determine the cause of the defrost system to stop working. here is a list item or causes that would stop the defrost system from working.

Defrost time just hang up and stop running.

Malfuctioning Defrost terminator hanging up and sometime works or other times not work.

Defrost elements is defective or loose connection at the tie in at the elements for the wire to connect.

=============================================

Now what i have heard so far it is working good now but if it messes up it will not show up as a problem for 7 to 14 days and you will see it freeze up again. now this might be the best cource of action here because of tring to do all the testing to see a refrigerator running good. wait 14 days to see if it screws up again.

=============================================

Now here is what I think and really off the record here. I think the defrost timer stop on you and when you moved it it unstuck it and went back to working. If it is frose up the heater will most of the time will not be enough to do a total recovery from the start of it all froze up.

TURTLE

Reply to
TURTLE

I understand that fully, and do the same thing.

. Also made me aware how much current is used.

Remove NOPSAM to email me. Please let me know if you have posted also.

Reply to
mm

Hi Turtle,

Thanks for confirming my measurements!

I have not measured the defrost cycle. I'm quoting from the wiring diagram and info that was on the back of the fridge. It states: Defrost Control 12 hrs. @ 40 min. Defrost Thermostat 60-28degF. But it was at least 30 min, just from what I remember.

OK.

OK

The "loose spade" I found was the power to the timer coil. There's a "post" wire, which is crimped to the spade connector. It is that crimp that was loose. The timer motor wires are like human hair and are wrapped and soldered to that "post wire".

I found the loose connection as I was measuring timer motor resistance. The measurement was varying, due to the post moving.

FWIW, I also found a spot on the plastic timer cam, where there was some melting of plastic. Suspect the motor stopped and contacts did not break cleanly and perhaps "cooked" for a while. I cleaned up the cam and put it back in. Cleaned up the contacts in the timer. They break the full load of the compressor, which is about 2A as you've confirmed.

Will watch for a while. After a few days, I will pull the panel in the freezer and see how much frost has accumulated on the coil, if any.

You got it! I wrote that above.

Thanks for your help. I've been able to troubleshoot several things in the house, thanks to the help from this Group.

Regards,

Rich

Reply to
RichK

Three easy ways to tell if it is working.

  1. put it in the defrost cycle and look at the heater, it will turn red. Even the metal heaters turn red.
  2. Wait for the defrosting to begin. You'll hear the water dripping on the heater, water should show up in the drip pan.
  3. Put it into defrost and put the plug in and out of the wall outlet. If it's working you'll see a pretty good spark.

Reply to
Ed

This is Turtle.

There is one thing i left out. In the refrigerator service business there is a old rule that says if there is a dought as to what the problem was with the defrost system. As a rule you change the defrost timer and move on.

TURTLE

Reply to
TURTLE

And with the refrigeration techs that know what they are doing, they find out whats wrong and dont throw parts at it.....

Guess your daddy was a parts changer. Like Father......

>
Reply to
CBHVAC

"TURTLE" wrote

That's not the rule for me. It's a pretty simple diagnosis. Heater, limit switch, timer. Even the newer adaptive defrost models with electronic controls are easy to figure out.

I would not like changing a timer only to get called back.

Reply to
Ed

This is Turtle.

I see you have never worked on refrigerators and dealt with the problem of the refrigerator defrost systems.

OH and the Refigerator Super tech like Sears has that works on these refrigerators. They are told the system it too complext to work on and here is what to do. If it is out of the 5 years warranty -- Call the compressor bad. If it is under warranty -- call back and we will send out our warranty tech to see about it. The Warranty tech is to just doctor it up to get to the 5 year warranty limit so they can walk out on it. If he fails they just wait till the customer sues them and if not they are off the hook. If the sue, they just replace it. I was told that 10% of the customer will sue and 90% will not sue the company.

I can just picture CB scratching his head at a Electronic Dual control side by side refrigerator with flipper door for the cooler area temperature control. Now bullshit don't walk here you have to know what is the problem.

HVAC sales must be poor to see you here so much.

TURTLE

Reply to
TURTLE

this is TRurtle.

first These words was not written when they had electrinic controls, but on standard block timers.

Second You don't need to spend about 6 to 8 hours at the refrigerator customers house and change him about $500.00 on a $500.00 refrigerator to hunt down a defrost problem. You ohn out to see the defront terminator it ok, then you ohm out the defrost element is ok, and then see if the defrost timer is running. Now Ed , you do all the test you can do on this refrigerator and still find nothing wrong . Now What do you do ?

Thirdly the words that i stated was the old time refrigerator service people [ not me ] who have workied on these refrigerator all thier lives and have this as a rule of their business. I was told this by all the refrigerator service people eversince i was a kid [ 40 something years ] when you can't find a problem with the defrost system -- change the defrost timer. Also sears tells their tech this same words when they can't find anything wrong with the defrost system -- change the defrost timer.

Fourth No disrespect at all but these words have been carried down the through the years and is still used in the refrigerator business today. Now what i think here. On the old stuff i would say yes , but on the new stuff NO, Sorry if my opinion differes from your !

TURTLE

Reply to
TURTLE

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