Fridge cooling unit fan - Montana Owners Club

rlrich · 07-16-2007, 09:31 AM

After finally getting the cooling unit on the fridge replaced, I have begun to suspect the cooling fan mounted on the rear of the fridge. There is a thermostat or sensor of some sort mounted on the fins behind the freezer portion of the cooling unit that controls the fan. Out of curiosity I jumper wired across the sensor and heard the fan run. I had never heard this fan run and it is very easy to hear. I checked the temperature at the fins behind the freezer and found 115 degrees. Manually jumped the fan to run and the temp dropped to 108. Tilted the top of the plastic grate out for better airflow and the temp immediately dropped to 103. I had also shot the temp of the cooling unit tube with my infared thermometer as it exits the top of the flu and found 290 degrees before the fan was turned on, 270 degrees after. The plastic grate seems to seriously restrict airflow. I would think there would be a better design for fridges such as mine mounted in a slideout. The hot air has to make severe downturn to exit through the grate to the outside.

Does anyone have any idea at what temps the rear cooling fan should kick on?

sreigle · 07-16-2007, 09:50 AM

I don't know what temperature kicks on the fan. If your refrigerator is not in a slide there should be a vent at the top for the hot air to exit. You might make sure there is no obstruction there, such as a bird nest or mud dauber nest.

If in a slide, then there should be a second cover above the first one to exhaust the hot air. Same story, check for obstructions although I don't see how that one could be entirely plugged.

The thermistor on the fins should control refrigerator temperature. It is used to fine tune the settings from the button along the top. Higher on the fin should cause cooler temperatures in the refrigerator. I was not aware it also controls the fan but obviously it does. Thanks for that information.

rlrich · 07-16-2007, 10:38 AM

Steve - the thermostat I was talking about is mounted on the fins that are part of the cooling unit behind the freezer. These are located behind the second cover that you speak of on the outside. Sorry about the confusion.

sreigle · 07-16-2007, 11:03 AM

My fault, Rick. I was not aware of the one outside and was thinking thermistor/fin inside. I'll have to check that thermistor on ours as I've never heard the fan run. Maybe I'll jump it like you did to make sure it works. However, it's in the 90's outside and the fridge is working well on 4 so it must be ok.

bigmurf · 07-16-2007, 11:20 AM

I added a outside fan to ours. I mounted the switch on the inside light cover. Any time I think it will be hot I can turn the fan on. It uses very little battery anyway so if I forget to turn it off, no big deal.

rlrich · 07-16-2007, 11:28 AM

Steve - Here's an interesting note. My fridge has been set on 4. Freezer temp has been right at 0 which is fine. Since I jumped the fan and let it run most of this afternoon with temps in the 90's today, the freezer temp has dropped to -10. Moving some air across the cooling unit in the rear seems to increase the efficiency of fridge considerably. That's why I wonder when the rear fan is supposed to come on. I don't think mine ever was coming on.

rlrich · 07-16-2007, 11:31 AM

bigmurf - That's what I'm going to do. Go get me a switch and mount it inside so I have manual control of that fan.

sreigle · 07-16-2007, 11:37 AM

Rick, if we assume the fan is doing as it is supposed to and zero in the fridge is the target (which I think is correct) then it looks like a switch connected in parallel across the thermistor wires would give you the ability to turn that fan on when you want it on without affecting the normal operation. Or maybe this is what you're saying.

The additional fan is a good idea, also.

lawrenceb42106 · 07-16-2007, 02:52 PM

Had a thermostat on the outside go bad on ours. Called the dealer about a new stat . He didn't know there was one. So called Dome tic and they said you have to order a new cooling unit. That they didn't sell the stat separate. Found a old unit that had been taken out. got the stat off of it and good to go now.

rlrich · 07-16-2007, 03:08 PM

Larry - Any idea how often your fan runs and what kind of outdoor temps gets it started?

lawrenceb42106 · 07-17-2007, 02:50 PM

rlrich

According to the # on the switch it should operate at on 105 F off at 90F. That is coil temps that work the switch. This is for a single door ref. Ours runs most of the time when running the ref. It will cut off on cool mornings. We have warm temps and high humidity here.

gungho · 07-18-2007, 04:34 PM

Ours seems to start run when the outside temp is about 85, and after that its dependent on fin temp.

rlrich · 07-20-2007, 04:46 PM

Larry or Jon

Can either one of you tell me where the thermal switch is mounted on your cooling units? I never paid any attention where it was located on my old cooling unit. They mounted it on the fins behind the freezer on the new unit. The fan has still never kicked in on it's own. The only time it runs is when I jumper wire it. I laid my outdoor temp sensor on those fins and have seen temps as high as 130 degrees. That just don't seem right to me. I think that thermal switch must be bad or mounted in the wrong place. As soon as I turn the fan on the temp will drop 20 degrees.

lawrenceb42106 · 07-21-2007, 12:07 AM

rlrich
Mine is located at the top right hand corner at the very back. You have to look close to see it. It is about the size of a dime with 2 wires coming off of it. It is about a !/2 inch thick. You have to take the top cover on the outside off to see it. Ours is built into the slide out.

Larry

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