Refrigerator Fins Freezing Up

[wolfe10]

NOTE: MOVED TO NEW TOPIC FROM "Refrigerator not working on propane"

John at jwsties@aol.com is the author of this post:

I have a 2004 Safari Cheetah with a Norcold four-door refrigerator. The cooling unit on the Norcold was replaced in July of this year before a long trip to West Coast.

RV Masters in Houston, Texas, replaced the unit under extended warranty and the warranty (Prizm) would only authorize a

refurbished unit, which I have heard has a pretty good track record.

The installation, which included a new propane activator PC board, checked out okay in an overnight test. So,l we picked up the coach and headed west.

For several days, the unit was cooling well, including freezer/ice maker operation. However, the fins at the back/top of the refrigerator are now frosting up at the end where the temp sensing thermocouple is attached. About six to eight fins are involved and will not defrost.

My question is: Does this indicate that the new cooling unit may be defective? Could it be the thermocouple was left disconnected during the cooling unit changeout, etc.?

We have rearranged the refrigerator contents away from that end of the coils, thinking maybe air circulation in the "box" has been compromised due to blocking.

Any suggestions?

John at jwsties@aol.com

[wolfe10]

John,

Two things you should check:

1. What is the temperature in the refrigerator? If below 33 degrees F, can you turn up the refrigerator thermostat (some models have this feature, others do not) and bring the temperature up to the 35-39 degree range?

2. Have you checked your door gaskets?

Door gasket test: With a $1 (A $20 works even better) close the bill in the door repeatedly all around the perimeter of the refrigerator and freezer door. The bill should pull out with the same tension all around and require firm pressure, but not close to enough to tear the bill. If the door has settled so the gap is larger at the top, allowing lots of extra humid air in, it CAN be shimmed easily on most models.

Certainly, the more humid the environment and the more frequently the refrigerator is opened, the more moisture WILL get in.

And you CAN defrost it. Turn off the refrigerator. Wait an hour. Remove food that obstructs your access to the cooling fins. Use a hair dryer ON LOW and KEEPING it OUTSIDE the refrigerator itself. Aim the dryer at the fins.

Also, be sure to defrost the freezer (same technique) when ice builds to 1/4". Ice is a GREAT insulator and you do not want the cooling unit insulated from the interior, as you DO want heat transfer out of the refrigerator and freezer.

Brett Wolfe

[Guest 2driftrs]

Brett, here's a good question for you that's kind of the opposite problem - - we have a difficult time getting the fridge section to cool. The freezer section will get to zero and stay there at a mid-point thermostat setting, but the fridge section will often get no colder than about 50F. Note that temps were taken with an infra-red probe. If I push the thermostat higher to get the fridge colder, the freezer section makes ice cream like bricks! All the door seals are AOK with no leaks.

This is a Norcold N621, and it has a thermistor attached to the fins in the fridge. Is this what controls the fridge temperature? Might it need replacement? What baffles me is the freezer compartment works great, but it almost seams that the fins have been isolated from the freezer!

Thanks for any ideas you might have.

Barry and Jan

[wolfe10]

Barry and Jan,

Yes, the thermister controls the "on and off" of the cooling unit.

The "coolant" goes through the freezer first, then to the refrigerator. NO separate controls for freezer/refrigerator.

The most accurate way to measure temperature in the refrigerator is to put a thermometer in a glass of water. Much more accurate than an IR or thermometer just in air.

And as you suggest, if you have a refrigerator model that does not allow you settings to control temperature, moving the thermister UP on the fin makes the refrigerator colder (and of course the freezer as well).

If the same (too high) temperatures are experienced on both 120 VAC and on propane, that would suggest that you need to relocate the thermister higher on the fin.

If this occurs only on one heat source or the other, you will need to troubleshoot that source.

Brett Wolfe