I'm helping a friend fix a fridge remotely. The compressor tried but won't start.
I suggested he check continuity on the run and start windings, the starting relay, and the starting cap. Ooops, it has none!
It's been 20 years since I took Machines, but I got an A. [And the fridge is not much younger...] But I don't recall any capacitor-less single-phase AC motors with good starting torque.
What gives?
-- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that\'s close........[v].(301) 56-LINUX Unless the host (that isn\'t close).........................pob 1433 is busy, hung or dead....................................20915-1433
Beware of friends bearing broken devices.
Are you getting a clicking sound (i.e. overcurrent shutoff) or a grinding sound (loss of lube)? Did this happen just after he moved the fridge (broke loose the crud at the bottom of the compressor)?
It certainly does have a relay. Look on the compressor schematic. It's labeled "PTC Relay" on the schematic. Depending on the model, you might get lucky and find that it's removable.
You get an "F" for this posting. Asking a repair question without supplying the manufactory and model number is a capital crime. Turn in your deploma and slap yourself on the wrist with a wooden ruler.
Also, while there may be some electronics inside a fridge, methinks that one of the appliance repair forums or newsgroups might be a more appropriate place to ask your question.
If it's 20 years old, it's quite possible that something in the compressor has worn out. A freon leak will eventually cause the compressor to lose lubrication and grind to a halt.
This might be helpful:
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
I'm not all that familiar with these motors, but they have been made without starting capacitors for quite a long time. I don't remember how long it's been since I've seen a household fridge with a starting cap, maybe in the
60s or 70s, and those would've been old models at the time. Maybe exceptionally large household or commercial reefers still use starting caps.The relay and overload are the motor's control and protection devices.
One possible motor failure mode could be that the motor was in the run cycle and a brief power disruption caused the motor to try to restart before the relay had time to reset (these typically aren't electromagnetic relays lke common ones with contacts actuated by a coil). During these power-fail restarts, the winding can open if the overload doesn't open the circuit in time. I've seen these events happen a couple of times, and the unit just hummed until the overload opened to protect the motor.
You're correct, in that many machine, utility or appliance motors do have greater starting torque when fitted with a starting capacitor, but the small, hermetically enclosed fridge motors in consumer fridges aren't the same.
If the fault is within the motor enclosure or cooling/freon components, the only practical option will probably be to replace the fridge.
-- Cheers, WB .............
He was asking about the omission of the motor starting capacitor, Jeff.
-- Cheers, WB .............
yep...
It's cycling on overcurrent. Been there for 10+ years.
It is. But there's no cap.
GE Hotpoint CTX18BACGRWW.
But the print shows all we know...
The people here are far smarter.....
-- A host is a host from coast to coast.................wb8foz@nrk.com & no one will talk to a host that\'s close........[v].(301) 56-LINUX Unless the host (that isn\'t close).........................pob 1433 is busy, hung or dead....................................20915-1433
There's your clue. The motor is either grinding, not turning, stuck, or fried (shorted winding). In all cases, the motor/compressor assembly appears to dead. It's sealed, unrepairable, and probably a good candidate for eWaste.
Past performance is not a good indication for future results. Works for stocks, investments, and refrigerators.
I haven't bothered to check, but I don't recall seeing a starting cazapitor in any of the assorted refrigerators I've owned or attempted to repair in perhaps 20 years.
Thanks. The diagram shows that the relay is replaceable. However, I doubt that's the problem. It might be that the overload sensor is tripping too early. Tear the relay and overload assembly apart, clean all the junk out, clean the contacts, and look for damage. You might get lucky.
Read the following:
Note the photos of the various relay failures.
I'm not sure I want to suggest this because there's too many ways this can go awry. Just be very careful. Take an insulated stick and jam the relay closed so the compressor is running. MEASURE the AC current or load with a AC wattmeter or clamp on ammeter. If it's sky high, give up. If it seems in spec, listen to the compressor. If it sounds like it's grinding, you're out of coolant. If it wobbles, you've blown a bushing. If it purrs, it's ok and there's something wrong with the relay or its the overload detector.
Nope. Just mention something political and watch the average IQ drop dramatically. Also, I sometimes get bored fixing computahs and printahs. Next time, I'll play dumb.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
The motor doesn't need a lot of torque when the high side bleeds down. Until then it can cycle on the overload until the high side bleeds down if cooling is called for.
Check the start relay and winding.
Here's a bloke who knows how to get people onside. ;^)
--
W
. | ,. w , "Some people are alive only because
\\|/ \\|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
Let's not go there...
--
W
. | ,. w , "Some people are alive only because
\\|/ \\|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
It's probably inside the compressor case.
...
A PTC relay is solid state, like the degauss posistor in a CRT TV set.
I fixed a 20+ year old Whirlpool with a bad overload. The repair consisted of taking out the start relay (bouncing armature type) and the bi-metal click disk overload switch, and gluing a GE brand PTC relay on the side of the compressor with silicone glop and tie-wraps. (It includes the overload function). Three wires: 1) power in from the main thermostat and/or defrost timer, 2) start and 3) run wires to the compressor.
Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)
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