Thermisters ???

[Jerrybo66]

There has been many questions about how to regulate the temp of their refers. Answers have boiled down to move up to a colder temp and down to warmer. Maybe it's the wine that has given me the courage to ask, "how come". How does the refer know how to regulate the temperature just because that little piece of plastic is up or down on the aluminum fin? Inquiring minds would like to know, including those who didn't want to be branded as dummies..:)

[dougrainer]

This is what the cooling tube looks like behind the fin plate. <
The COLDER part of the cooling tube is at the top. The Extreme cold comes from the freezer tubes and then down. It flows to one side at the top of the evap plate, makes a 180 degree curve and flows to the bottom back of the evap plate. The Thermister is installed inside that plastic clip on the flat fin. The Evap fins will be 10 degrees colder than the inside of the refer. If the evap fins are 26 degrees the inside of the refer will be 36 degrees. Sliding it up and down on a NON adjustable Tstat refer will only yield at best a 4 degree temp difference. The Thermister senses the FIN TEMP, NOT Air temp. Doug

[wa8yxm]

How come moving it up gives you colder temps.

As you know. There is a major UP-DRAFT over Capitol Hill (most all "Capitol Hills" due to all the hot air that is given off in the houses of government. (NOTE: this is a joke).

Seriously. "Hot air rises" thus in the fridge the top is warmer than the bottom. Moving the thermisistor UP moves it into an area that is naturally Warmer,, and since it is the sensor for the thermostat, when you cool that spot to the target temp. The rest is colder. Moving it DOWN moves it to a cooler level, so now the rest is warmed a bit because the sensor cools sooner.

[Golden_HVAC]

Old-Biscuit wrote:
Moving the thermistor will only affect temp IF the fridge does NOT have an adjustable temp control on upper panel (non-adjustable temp setting)

It is attached to the cooling fin in food section.
It has a sensor (bulb) on the end of tip.

It provides feedback to temp control.

Moving it up (into warmer area of fridge) will make cooling cycle longer (more cooling)
Moving it down (into cooler area of fridge) will make cooling cycle shorter (less cooling)

YET.....if it falls off and is laying down in lower section of food compartment fridge will go into continuous cooling resulting in frozen food

I would like to offer a slightly different theory, you can take both and use it to your advantage.

The cooling coil is cold. Perhaps colder in the center than at the bottom. If the cooling coil is say 25F at the back, where the heat exchanger meets with the coolant (ammonia and water mixture) then the fins collect heat and transfer it back to the colder area in the back of the refrigerator section. So the fins might be say 30 at the bottom edge (no more cooling beyond this point) and 28 closer to the center of the heat exchanger - this means that moving the sensor up will get it to a cooler area, thus shut off the cooling control sooner, while moving it to the edge where it is warmer will run it longer. Taking it off the cooling coil, and it might never reach 28F and shut off the gas valve - thus everything will freeze inside the refrigerator section.

I prefer a adjustable thermostat. If people would walk into a RV, see that the temperature is not adjustable, and complain to the person in charge of the RV sales lot, then drive away, manufactures will stop installing non-adjustable thermostats in their RV's. But as long as "We the buyers" accept non-adjustable thermostats, they will keep installing refrigerators that are $50 less than the model that has an adjustable thermostat.

Fred.

[Old-Biscuit]

Moving the thermistor will only affect temp IF the fridge does NOT have an adjustable temp control on upper panel (non-adjustable temp setting)

It is attached to the cooling fin in food section.
It has a sensor (bulb) on the end of tip.

It provides feedback to temp control.

Moving it up (into warmer area of fridge) will make cooling cycle longer (more cooling)
Moving it down (into cooler area of fridge) will make cooling cycle shorter (less cooling)

YET.....if it falls off and is laying down in lower section of food compartment fridge will go into continuous cooling resulting in frozen food

[old_guy]

heat rises.