Well, it took a long time to thaw out the freezer.
I pulled it out of its cubby and removed the back panel.
Trouble-shooting
One of the keys to trouble-shooting or diagnosing problems is to split the system in half and isolate which half contains the unexpected performance. That supposes that you can noodle out what "expected" performance is.
The alternative to searching for the problem by bisection is to start randomly replacing parts. That gets expensive when parts run $50-to-$350.
When possible, I like to look things over and then sleep on it. I am a morning person and I do my best work in the morning. Sleeping gives my brain time to puzzle out the curiosities.
Relays
For example, I identified a "black ice-cube" that I am 95% sure is a relay. It only has three wires going into it.
A relay is a device that takes a "signal" and uses that signal to activate or turn off a power feed. It is a very crude, binary (on/off) amplifier. Internally, a relay is typically a solenoid or a linear electric motor and a set of contacts.
The engineering rational for using relays is that less expensive sensors (thermostats) can be used because they do not have to switch large, inductive loads. Another advantage is that thinner, more flexible wires can be used which saves space and makes it easier to assemble the unit. In automotive, jobs content that involved handling the main body wiring harness was one of the least desirable jobs in the factory because it was like wrestling with an octopus.
My expectation was that relays would have two "signal" wires (thinner) and two "power wires" (thicker) but this one only had three wires. That suggests that the signal shares the leg-to-ground with the power wires.
Since the function of the relay appears to be to turn on the power when the thermostat signals that the compressor needs to run, one way to test the system downstream from the relay is to disconnect the wires and jumper across the two power wires and then plug the refrigerator back in. If the sealed unit takes off and runs then I either have a bad relay or a bad thermostat.
Another thing I can do is to plug into a Kill-a-Watt and see if the refrigerator is drawing power other than the internal lights. Given that I don't hear any humming, I don't expect that it does but it is one more thing to check.
Limited access
The back panel isn't very large. There could still be cheap-to-replace components that failed but I am not sure I can get to them. For instance, some refrigeration units have a snap-disk thermostat on the condenser to shut off the compressor if it senses an over-temp. Not only can the snap-disk fail but wires can fatigue and electrical connectors can vibrate loose.
I get a great deal of satisfaction in trouble-shooting systems but my batting average isn't very good on refrigerators and freezers.
Modern refrigerators are designed to fail. My mother still has a refrigerator from 1980. Works fine. Only had to replace the door seal. I'm on my third one in the past 15 years. Designed obsolescence. Things aren't built to last and they are designed to so that it's easier/cheaper to replace them than repair them.
ReplyDeleteJoe, I wouldn’t jump or bypass that relay. Yet. There should be a snap action overload (thermal protector) on the can (hermetically sealed compressor). That snap action overload is designed to protect the can. The relay does exactly as you suggest, but it cuts the start winding in and out of the compressor motor.
ReplyDeleteClean the coil. Are you getting any water out of the evap drain tube? This would mean the evap coil might have been iced up. With the fridge plugged in, and the thermostat turned to its normal setting, find the door light switch and cycle it 5-6 times rapidly. See if the compressor stops running. This maneuver cycles the defrost timer. If the timer is bad, no defrost, and the evap coil ices up.
THank-you for the tip
DeleteSince time immortal, household appliances have had a schematic installed somewhere in the unit. Is it pasted to the inside of the cover? Folded up, stuffed in a plastic bag glued inside the compartment? That schematic had gotta be there somewhere. Right now it's your DVOMs bff...
ReplyDeleteHappy to help if you need it. (31 yr appliance repairman here.) I would not start by bypassing relays although that could be your problem. You were on the right track when you started to break the system down into parts and asked yourself what does not match with what you think should be happening. Another way to ask this is, 'what is not running' or 'what component is not performing it's task.' Again, feel free to DM if you want some free help.
ReplyDeleteThe only fridge I fixed was a pretty obvious pair of bulging capacitors on the main circuit board. Once it gets past cleaning the fins (if it has them) and checking the fan, I'm pretty much out of my league. :)
ReplyDeleteSometimes the wiring diagram is on a folded up piece of paper behind the grill in front of the fridge. In my older fridge, there is a motor-driven defrost timer which kills power to the compressor and fires up the defrost heaters; if the timer motor quits during a defrost cycle, it won't cool. Usually there is a knob or screwdriver slot you can use to get out of the defrost cycle if that is the kind you have.
ReplyDeleteThat three-wire device could be the overload or a starting relay for the compressor.
I found a couple of wiring diagrams in the home improvement section at stackexchange (diy.stackexchange.com). Sometimes you can find a schematic at partselect or repairclinic, or even the manufacturer website. I scanned our GE wiring diagram, and can email if you think it might help.
Another thought...If it's a new enough unit, say 8-10 years old, it may have jumped into "demo mode", where the lights work but the compressor doesn't. It's so it can be plugged in at the store and you can see how pretty it is without wasting energy on cooling. I've had my Samsung do that twice for reasons unknown.
ReplyDeleteI will note that it hasn't happened since I installed one of these fancy surge protectors-https://www.amazon.com/gp/product/B00D7KP8S4/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Short version is that when the power goes out and comes back on, this delays the startup of the connect load for a few minutes. I have them on several items where a sudden on-off-on could cause problems.
Most any fridge after 2000 has a motherboard that runs everything. Could be your problem??
ReplyDeleteI have had a bad starter capacitor prevent the compressor from running before. Those are relatively cheap. Check that if you are able. Although these usually stink when they fail they don't always.
ReplyDelete