Refrigerator - freezer defrost test

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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
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RichK wrote:

A clamp-on ammeter on the switched lead from the defrost timer to the heater ought to tell you.
HTH,
Jeff
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Jeffry Wisnia

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Of course, the defrost lead will only be drawing amperage if the bimetal is cold enough. But, that confuses things.
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Christopher A. Young
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"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
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RichK wrote:

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. <G>.
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.)
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Jeffry Wisnia

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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
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RichK wrote:

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
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On Thu, 22 Dec 2005 15:03:47 -0500, Jeff Wisnia

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.

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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
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I understand that fully, and do the same thing.
. Also made me aware how much current is used.

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RichK wrote:

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
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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
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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
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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.
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
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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
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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......

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CBHVAC wrote:

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
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Nah...never....just 5 commercial accounts with an average of 6 units in each one.. Plus god knows how many more that were referals over the years...

Im not fucking Sears. If you base your repairs on what some funky does, then you are as bad.

Or how about the units with a vac switch that lets it know that the doors been shut, and the unit can start back up again? Seen those Terry? Ever try to figure out a side by side reach in that wont start but yet, everythings fine?....

As a one man band, I dont expect you to know a thing about how to manage time with other crews out working...and truth be known, new installs are now being scheduled for MARCH. Sales are up quite a bit...but then, again, I dont expect you to know much about that, being that you, as a one man band after all this time, cant sell, repair, install, diagnose, etc, but one at a time, while we have crews out that can do all that at the same time../.while I sit here and go...wow...amazing how business has gone up this year and we are not working any harder.
Oh...now.....excuse me, cause its Christmas and I gave most of the guys the day off, its after 12 noon, and I have a duct system to go install so that tomorrow, all the guys have to do it run a lineset and gas pipe. You DO know what a duct system is dont you Terry? Its those round hollow things that you have to wrap with duct insulation.

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replying to CBHVAC, reality calls wrote: these modern refrigerators are half bullshit. a defrost timer and defrost thermostat, should be EASILY ACCESSIBLE on the inside of the food/freezer compartment, or on the outside. not buried behind all the shelves and back covers, requiring taking all the food out, and putting it in a cooler, to work on it. BAD DESIGN CALLED on all modern appliances that don't have easy access to these critical controls. #2, dust blocks the condenser coils- BAD DESIGN CALLED AGAIN- a filter that is easy to clean or change, is needed, just like an AIR CONDITIONER has ?? WTF designed these appliances ? dumb idiots ? nothing worse then working on the back end w/compressor, start components, and the damned thing goes into DEFROST MODE, and you have to sit for 15 minutes waiting for it to finish, just to continue troubleshooting the first problem- OR take all the food out and put it on ice- this is total BULLSHIT. if I owned an appliance company and my engineers put forth such a design, I'd threaten to fire them- and they'd deserve it. it's like designing a car radio without a volume knob for cripes sakes. what morons invented this stuff ? an old wooden frig with a block of ice worked better. one thing went wrong- the ice melted eventually. big deal, put another block of ice in.
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I think you need to be less eager to call others morons. The message you're replying to is well over a decade old... moron!
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