dometic refrigerator not staying cold

[medic8ted]

I recently purchased a 1982 TT with a refrigerator which was not the original. I cannot find a part number anywhere but it is an older domestic brand 120v/12v/propane model without electronics. When running on any fuel, the piping gets warm an it cools to 40° in the fridge and 20° in the freezer but soon raises back up to 60°. When I bought it, the space above the fridge was open with a board covering the opening. I put a board in the back of the dead space to keep the "ventilation shaft" contiguous all the way up which I can see the roof vent from the access hole in the side. I also placed a small fan inside that shaft pointing up to help increase airflow in through the louvers in the access panel and out the roof vent, yet the problem continues. Once the fridge heats back up it never cools back down. Does anyone have any more ideas? The door seal is not great but only has a very small gap in one of the bottom corners. A new 3 way fridge is out of the question, that will cost more than the trailer.

[Gale_Hawkins]

After 24 hours a really healthy frig in 90F air temps during the heat of the day can see upper/lower box temps of Zero/28F early in the mornings with air temps of 70F when set on high.

In our 1992 Norcold 6162 frig if on high we are at -5/25F in the morning with outside temp of 70 and it hits 100F in the MH that afternoon we can bet the boxes will be at +5/35F with our replaced cooling unit.

Every 3F rise in air temps for us equals 1F rise in the temps of each box. The 30F spread between boxes seems to be set in stone in our case. There must be a dozen old posts with detailed testing data done over and over under different conditions.

[medic8ted]

2 steps forward, 1 step back. Return coil is cold nearly to the bottom, but fins at the top don't feel too cold. Temp tonight is 62° in fridge, 40° in freezer. Weather is warm and really humid with storms off and on with sun in between. Will check in the morning. Partial blockage?

[Gale_Hawkins]

You are making progress.

[medic8ted]

Update again. It has been running on 120V for about 12 hrs. Temp outside is 64° with rain. Temp inside is 58° and my hand almost stuck to the freezer wall when I touched it. Lower coil is warm on the bottom couple pipes but noticeably cooler on the top 1/2. Heading to work and will check back this afternoon when I get home.

[Gale_Hawkins]

If you have some blockage forming it can reduce the ability to cool as well.

[medic8ted]

Another update and another question...Now the temp inside was 80° and everything on the back was warm. Shouldn't the coil be cool coming back down toward the heating coils be cool(er)? Well it was getting warm about 2/3 of the way up. The top coming out of the heating area is hot to touch and the return area is pretty warm. Could overheating cause a problem internally? I unplugged the power and it cooled off pretty quickly and I just plugged it back in and the bottom part of the return line warmed up pretty quickly. The fan I added is directly above the cooling fins on top, blowing up toward the roof vent.

[medic8ted]

Thanks all for the help. Here's an update. The rear baffle has about 1/16" gap all the way around it and is even with the back of the fridge, so it makes a fairly smooth continuation of the wall all the way up to the vent. The door seal actually seal with a little persuasion on the bottom corner creating a pretty good seal all the way around. I have put 7" insulation on top of the unit in the dead space. The fan is creating airflow proven by drawing smoke from outside of the louvers and exiting out the roof vent. Ambient air temps have been in the mid to upper 70's all week, going down to 50's at night. I added the insulation and pushed the door shut tight about 2 hrs ago and already it has dropped 2 degrees and there is a noticeable difference in the temp of the pipe near the top of the fridge. Will post back updated temps tomorrow morning and afternoon, forecast to be near 80 tomorrow with chance of storms. Right now is 76° and inside temp is 58°. Also I have no fluorescent lights anywhere, all incandescent 12v lighting.

[Old-Biscuit]

Here is a manual for Dometic 3 way fridge.....LINK

Ventilation/clearances are very important

AS is a good, fully closing/sealing door. You stated " The door seal is not great but only has a very small gap in one of the bottom corners"
A small gap is a HUGE cooling loss.

Didn't your Mom ever yell at you......"Close the door. We're not trying to cool off the neighborhood"

You can NOT get fridge cold enough with a 'gap'

Fix the door gasket before any other fixes.......
New door gasket
Re-adjust door
Warm gasket with hair dryer.........until pliable then close door and let seal reform (This is a last ditch repair....sometimes works)

[midnightsadie]

PUT A BUNGEE CORD ACROSS YOUR FRIG DOOR SEE IF TEMP DROPS. DOOR GASKETS ARE INPORTANT.

[Wally_Walleye]

This may be a long shot but we had an older motorhome in which the frig did the same thing. Took it in for service and it turned out to be one of the old flouresent lights that was interfering with the thermostats. Like I said a long shot but might be worth looking into.

[otrfun]

How close did you position the "boards" (baffle?) to the rear of frig? Have no idea what's appropriate for older units, but most of the newer units the baffle must be less than 1" away from the coils.

Does this baffle extend just above and below the lowest and highest part of the coils on the rear of the frig? If not, it should.

Was the area between this baffle and the exterior wall of your TT open? If yes, I believe this should be blocked off with insulation or something to prevent this open area from interfering with the overall air flow from bottom to top on the frig side of the baffle.

Not sure if that fan you're using is being effective or not. Sounds like it's too small. You may want to try using a regular 110v portable fan positioned at the bottom vent as a test (blowing in). If it improves cooling substantially, then at least you know the frig is capable of cooling better.

BTW, what are the ambient temps in your area?

[medic8ted]

I tried it with and without the boards in place. There are 2 now, where there was only 1 before. Right now it is a dead space on top of the box with a board on either side of it. Initially there was only 1 board on the inside, for cosmetic purposes. I then added the one on the back "flue" side. I didn't think about it picking up heat from the dead space above. Maybe some insulation laying directly on top of the box will help?

The fan I added was from the old converter/load center I replaced, unknown cfm, just hot wired to run all the time and assist. There is no insulation on the top coils, I reached up and pushed it back and can feel the top of all the piping which is warm but not hot.

[otrfun]

I would double check to make sure there's no insulation or other obstructions (dust, trash, paper) near any of the rear coils. Not sure how these older units are designed, but the "baffle" (the wall that faces the entire rear of the frig) on the newer units should be no farther than 1/2" - 1" from the rear coils. This small space creates a "venturi" effect and actually increases cooling when temps rise.

What kind of fan, CFM, and where is it installed?

I wouldn't ignore that small gap in the door seal. If the door seal won't hold a piece of paper then I'd seal it with something.

[Gale_Hawkins]

Have you removed the board you replaced and tried it?

Sounds like it may be picking up heat from the air around the box perhaps.