Ptc thermistor in a wine refrigerator

Thread Starter

sherlock ohms

Joined Dec 24, 2013
25
Wine fridge stopped cooling. Compressor would not start but would get hot. Found a post on line where a guy with a similar problem pulled the relay/overload off the compressor and found a little round ceramic disc which appeared spotted on one side. On a whim he reversed the disc, reassembied relay housing, and Voila!, the beast began cooling.
Question: im a self-learning amateur. This littlt disc might be a thermistor i think wich will initially allow current flow to the start windings. But why would reversing its direction in the relay housing have any influence on whether current was able to flow through it??
Many thanks in advance for any kind assistance
 

sailorjoe

Joined Jun 4, 2013
361
Sorry, Sherlock, but there's just too little to go on here. The little disc could have been a thermistor, an RTD, a capacitor, or a fluegalfram. Reversing it may have done something or maybe nothing. It's just too random. We don't know what would have happened if he had just removed it from the circuit altogether.
You could try replicating what he did. You could look for more ideas on line. You could call a repairman.
How would you like to proceed?
 

Thread Starter

sherlock ohms

Joined Dec 24, 2013
25
Sorry, Sherlock, but there's just too little to go on here. The little disc could have been a thermistor, an RTD, a capacitor, or a fluegalfram. Reversing it may have done something or maybe nothing. It's just too random. We don't know what would have happened if he had just removed it from the circuit altogether.
You could try replicating what he did. You could look for more ideas on line. You could call a repairman.
How would you like to proceed?
 

Thread Starter

sherlock ohms

Joined Dec 24, 2013
25
I don't agree it's random. I followed suit and flipped the little disc around. My compressor kicked on and the fridge fell to 45 F in minutes. So reversing the disc DID change something in the circuit. I,m just not schooled enough to understand what or why.
 

#12

Joined Nov 30, 2010
18,167
So reversing the disc DID change something in the circuit. I,m just not schooled enough to understand what or why.
Neither am I, and I fix 'em for a living! That's probably a lie, but I never bothered to autopsy one. The last time I looked, the local appliance parts store had several hundred of those ceramic starters in stock. That tells me they fail...a lot! I just replace it, the machine starts running, and that's the end of it.

You can replace your starter and autopsy the old one...or buy two and autopsy both a good one and a bad one. From here, we really can't tell if the only thing that happened was disturbing the dirt so it made contact again.
 

Thread Starter

sherlock ohms

Joined Dec 24, 2013
25
Neither am I, and I fix 'em for a living! That's probably a lie, but I never bothered to autopsy one. The last time I looked, the local appliance parts store had several hundred of those ceramic starters in stock. That tells me they fail...a lot! I just replace it, the machine starts running, and that's the end of it.

You can replace your starter and autopsy the old one...or buy two and autopsy both a good one and a bad one. From here, we really can't tell if the only thing that happened was disturbing the dirt so it made contact again.
Thanks for writing. Do you think this ceramic disc is a ptc? Would a ptc allow current flow only in one direction? I like your thought that maybe the surface was cleaned up a bit in handling and the reversal of the disc was not the prime factor.
 

joeyd999

Joined Jun 6, 2011
4,288
Thanks for writing. Do you think this ceramic disc is a ptc? Would a ptc allow current flow only in one direction? I like your thought that maybe the surface was cleaned up a bit in handling and the reversal of the disc was not the prime factor.
I think it was a bad solder job to start with. Resoldering is coincidental with flipping it around.

I bet if you flipped it again, it would still work.
 

Externet

Joined Nov 29, 2005
1,428
When the PTC pill was flipped, the electric contact points from its holder contacted another undegraded area of its surface and worked. Agree with joey that should work if flipped again.
 

#12

Joined Nov 30, 2010
18,167
Do you think this ceramic disc is a ptc?
I always get those mixed up. PTC means hotter = more resistance? If true, then yes, it's a PTC. It allows start current for just about a second, then heats up and sort of disconnects the start winding from the power. The low mass of the ceramic means the PTC will reset to the, "current available" condition in less than a minute, and refrigerator thermostats usually stay, "off" for several minutes during normal operation. They used to use current relays for this function. They don't need a quiescent time before they will re-start. They also failed occasionally. I have installed about one, in my whole life, but I mostly work on machines that are way larger and use massive start systems. Some, "hard start" kits contain a capacitor with a PTC already attached.

Let me try to put this in perspective. When I worked at Sears, each parts bin was labeled with a, "minimum low stock" number.
For instance, electric water valves for ice makers, MLS=3
95405 v-belts for clothes washers, MLS=6
When I see a parts bin with over 200 ceramic starters, I know immediately that they sell a LOT of them.

ps, "only one direction" implies a DC circuit. False in this case. This thermistor is a time delay device which passes AC current. It is merely a very irritable resistor that refuses to work for more than one or two seconds at a time.
 

Thread Starter

sherlock ohms

Joined Dec 24, 2013
25
I always get those mixed up. PTC means hotter = more resistance? If true, then yes, it's a PTC. It allows start current for just about a second, then heats up and sort of disconnects the start winding from the power. The low mass of the ceramic means the PTC will reset to the, "current available" condition in less than a minute, and refrigerator thermostats usually stay, "off" for several minutes during normal operation. They used to use current relays for this function. They don't need a quiescent time before they will re-start. They also failed occasionally. I have installed about one, in my whole life, but I mostly work on machines that are way larger and use massive start systems. Some, "hard start" kits contain a capacitor with a PTC already attached.

Let me try to put this in perspective. When I worked at Sears, each parts bin was labeled with a, "minimum low stock" number.
For instance, electric water valves for ice makers, MLS=3
95405 v-belts for clothes washers, MLS=6
When I see a parts bin with over 200 ceramic starters, I know immediately that they sell a LOT of them.

ps, "only one direction" implies a DC circuit. False in this case. This thermistor is a time delay device which passes AC current. It is merely a very irritable resistor that refuses to work for more than one or two seconds at a time.
 

Thread Starter

sherlock ohms

Joined Dec 24, 2013
25
When the PTC pill was flipped, the electric contact points from its holder contacted another undegraded area of its surface and worked. Agree with joey that should work if flipped again.
Thank you for this important info. I,m beginning to see things much more clearly.
 
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