Refrigerator weak on AC

[MNtraveler]

We have been on the road for over two weeks and the refrigerator has been working admirably (except for normal altitude issues with propane while traveling). Now we are parked in Colorado at elevation (about 6800') and it is working poorly on AC. Refrig temp has been up to 45 and even 50. Gas works better (as it usually does) (brings it right back down to 40) but is not reliable due to elevation. Sometimes it gets intermittent. I would really prefer electric mode. Here is what I have done so far:

Turned off house AC power. Checked refrigerator plug and it was fine. I plugged another item into the refrigerator socket and it is fine. I removed the refrigerator fuse box cover and the fuses are fine, as are all connections inside the box. Closed up and plugged in again and turned on house power and the refrigerator. I could hear the evaporator working very quietly but after 10 mins or so the tubes were not getting hot. (I know electric cool down is slower.) I switched to gas mode and of course it works better so the tubes got hot relatively quickly. The thermostat is pushed all the way up into the "cold" range as far as it can go. The awning is keeping sun off the side for now and the outside temp is only 67 going to 75 today.

Am I missing anything?

Thanks!

[pgandw]

Possibly an airflow problem. When on propane, the hot exhaust is used to help cause cool air flow across the cooling coils. I had to install an exhaust fan to get proper air flow across the cooling coils - without the fan, fridge performance was highly dependent on the direction and velocity of the wind. Based on advice from others, I installed a 12V 400CFM computer case fan on the exhaust grill. I used tie-wraps to hold the fan in place. That quiet little fan makes my fridge work consistently in all temps and conditions. I have to shut the fan off when temps get down in the 40s and 50s to prevent the fridge from freezing.

Another thought - the chimney above the burner also contains the AC coil. So that chimney should be getting hot regardless of power source. If it's not getting hot in AC mode, I would check the resistance (or continuity) of the AC coil to make sure there is not a broken wire or connection.

That's about all I can think of, others may have better advice.

Fred W
2014 Rockwood A122 A-frame
camping Colorado and adjacent states one weekend at a time

[Toddupton]

More than likely the element is out of spec and not heating to the correct temperature.

[MNtraveler]

Thanks!

Also should have mentioned I washed a bunch of dust off the coils from our road travels. Also that the refrig fins are not frosted up, in fact they have been wet to the touch. We are in totally dry areas (desert).

Just returned from 3 hours away and had left it in gas mode. The temp was OK (40-41) but should have been a bit colder. I have switched it back to AC mode to see if it can hold or not.

There is a mobile RV repair service that was just at the park this morning and if need be I can call him back.

[Knoxie89]

Originally Posted by pgandw

Possibly an airflow problem. When on propane, the hot exhaust is used to help cause cool air flow across the cooling coils. I had to install an exhaust fan to get proper air flow across the cooling coils - without the fan, fridge performance was highly dependent on the direction and velocity of the wind. Based on advice from others, I installed a 12V 400CFM computer case fan on the exhaust grill. I used tie-wraps to hold the fan in place. That quiet little fan makes my fridge work consistently in all temps and conditions. I have to shut the fan off when temps get down in the 40s and 50s to prevent the fridge from freezing.

Another thought - the chimney above the burner also contains the AC coil. So that chimney should be getting hot regardless of power source. If it's not getting hot in AC mode, I would check the resistance (or continuity) of the AC coil to make sure there is not a broken wire or connection.

That's about all I can think of, others may have better advice.

Fred W
2014 Rockwood A122 A-frame
camping Colorado and adjacent states one weekend at a time

Makes sense, we just adjust the fridge to a 'colder' setting on power and warmer on propane to fix it, but I like the 12v fridge fan idea. Am i reading it correct that you installed it outside the fridge on the back to vent air up and out of the 'chimney' to the roof?

[pgandw]

Originally Posted by Knoxie89

Makes sense, we just adjust the fridge to a 'colder' setting on power and warmer on propane to fix it, but I like the 12v fridge fan idea. Am i reading it correct that you installed it outside the fridge on the back to vent air up and out of the 'chimney' to the roof?

No, an A-frame is a pop-up with a 2 piece peaked roof instead of a 1 piece flat roof (and the a-frame has hard sides).

So there is no fridge vent to the roof. The outside fridge vents are 22" apart vertically (minimum Dometic distance) on the lower (fixed) part of the trailer. What I call the "chimney" is the insulated vertical canister that sits on top of the propane burner and transfers heat from the propane flame or electric coil (contained in the chimney) to the ammonia solution. The chimney should be hot to the touch when the fridge is working, regardless of heating method. It takes at least 10-15 minutes for my chimney to get hot.

The computer case cooling fan I installed is tie wrapped to the upper vent grill, and pushes the air out. I have enough slack in the fan wiring to allow the vent grill to be hinged downward or partially removed. There is also a wire connector if I wish to totally remove the grill.

If you have a roof vent for your fridge, the chimney effect of the tall space should be giving you decent airflow over the cooling coils. If everything is working right, the air coming out of the upper vent (side or roof) should be warmer than ambient air to the hand placed over the vent on even the hottest days.

Fred W
2014 Rockwood A122 A-frame
camping Colorado and adjacent states one weekend at a time

[MNtraveler]

Update: after running on AC for a couple of hours, the temperature was barely holding. I opened the fridge compartment again and found the tubes were hot, meaning it was sure running on AC! However with the tubes at 120-130, it was clear it was a heat dissipation problem. I got up on a ladder and there was no air flow obstruction. However although it was in the 70s outside I underestimated the heat of the desert sun. The roof was about 120 and the black Vent hood was about 130. I couldn't run down a portable fan at the park so I just left the compartment open all afternoon to ventilate. The refrig temp came down below 40 for a while. Tonight it's cool out but it's stuck at 41 again, which does not make sense. It's nearly OK but we'll be losing more food at this temperature.

[Herk7769]

Originally Posted by MNtraveler

Update: after running on AC for a couple of hours, the temperature was barely holding. I opened the fridge compartment again and found the tubes were hot, meaning it was sure running on AC! However with the tubes at 120-130, it was clear it was a heat dissipation problem. I got up on a ladder and there was no air flow obstruction. However although it was in the 70s outside I underestimated the heat of the desert sun. The roof was about 120 and the black Vent hood was about 130. I couldn't run down a portable fan at the park so I just left the compartment open all afternoon to ventilate. The refrig temp came down below 40 for a while. Tonight it's cool out but it's stuck at 41 again, which does not make sense. It's nearly OK but we'll be losing more food at this temperature.

Any shade at all will help you (tarp?).

You need to get the cooling load down as well. A small battery fan inside the fridge, and keeping the fins free will help. Contrary to a compressor fridge, an overloaded evaporator fridge will have trouble maintaining temperature.

Check door seals. An IR temperature "gun" can spot air leaks.

[DouglasReid]

on my previous camper I had to do two mods to get the refridge to work correctly. The cooling unit is dependent on air movement from bottom to top over the condenser coil at the very top of the cooling unit. Sometimes the manufacturer does not mount them correctly. You need as little air gap behind the cooling fins as possible to prevent the air from bypassing those fins. I put some 2" thick foam on the wall behind the fridge to give minimal clearance in that area. I combined that with a small 12V fan mounted beneath that to blow the air over those fins instead or relying on mere convection. It made a HUGE difference. It went from barely keeping 45 degrees in the fridge to 34 degrees and down to 12 in the freezer compartment

[MNtraveler]

Thanks for all the input. This seems to have resolved itself though I'm not sure why. I did move the thermometer a bit. LOL It seems to be holding at about 37-38 now. I do think a vent fan will be needed to help cool those hot coils. Many thanks!

[Ree]

Originally Posted by MNtraveler

We have been on the road for over two weeks and the refrigerator has been working admirably (except for normal altitude issues with propane while traveling). Now we are parked in Colorado at elevation (about 6800') and it is working poorly on AC. Refrig temp has been up to 45 and even 50. Gas works better (as it usually does) (brings it right back down to 40) but is not reliable due to elevation. Sometimes it gets intermittent. I would really prefer electric mode. Here is what I have done so far:

Turned off house AC power. Checked refrigerator plug and it was fine. I plugged another item into the refrigerator socket and it is fine. I removed the refrigerator fuse box cover and the fuses are fine, as are all connections inside the box. Closed up and plugged in again and turned on house power and the refrigerator. I could hear the evaporator working very quietly but after 10 mins or so the tubes were not getting hot. (I know electric cool down is slower.) I switched to gas mode and of course it works better so the tubes got hot relatively quickly. The thermostat is pushed all the way up into the "cold" range as far as it can go. The awning is keeping sun off the side for now and the outside temp is only 67 going to 75 today.

Am I missing anything?

Thanks!

We posted this last fall, maybe this will help.
We live and camp a lot in the South, many hot days
To date the Refrig is working great as stated below.
Remember to check you temp slider in the back inside of the refrig on the
the coils
REFRIGERATOR COOLING PROBLEM

Many owners have a refrigerator with two outside access vent covers. One low and one high. The theory is, rising hot air pulls cooler air into the lower vent and a the hotter air vents out the top. Then some genius thought the refrigerator coil fins were not seeing the moving cooler air so they installed a small fan blowing upward to the back of the refrigerator. Then because the coil fins are just about centered on the upper vent, another genius decided to block more than half the vent opening with wood paneling, reasoning the moving air would flow over the coil fins.

The fan in ours was annoying and noisy. We notice the cabinet walls next to the refrigerator were unusually HOT. Removing the vents exposed the wood paneling baffles. Removing the top piece also exposed there is no insulation around the refrigerator.

So, we have a vent that is mostly blocked, a fan to small to do any good and no insulation. And the refrigerator has a cooling problem? DUH!

SOLUTIONS: First, the heat has to get out from behind the refrigerator. It is much more important that the heat escapes than to have mechanical air flow over the coil fins.
I removed the fan and put a bullet through it. Next I cut out as much of the wood paneling blocking the upper vent as I could. I cut some strips of 2" Styrofoam to fit into the sides of the cabinet around the refrigerator closing off that cavity. There is a large cavity above the refrigerator and that was blocked by blocks of 2" Styrofoam. On walls if the cavity behind the refrigerator, I glued Styrofoam there to insulate the surrounding cabinetry.

RESULTS: Five days in Florida 90 + degree weather, evenings mid 80's. NO fan ! No Noise !!! Normal use each day.
Day 1 am - Refrigerator cooled prior to loading - Freezer 2 degrees, Refrigerator 32 degrees. Unit loaded with pre-cooled or frozen items. Propane cooling for 3 hours, 120 Volt cooling the balance of the time.
Day 2 am - Freezer 12 degrees, Refrigerator 35 degrees
Day 3 am - Freezer 10 degrees, Refrigerator 35 degrees
Day 4 am - Freezer 5 degrees, Refrigerator 35 degrees
Day 5 am - Freezer 5 degrees, Refrigerator 35 degrees

[MNtraveler]

Originally Posted by Ree

We posted this last fall, maybe this will help.
We live and camp a lot in the South, many hot days
To date the Refrig is working great as stated below.
Remember to check you temp slider in the back inside of the refrig on the
the coils

Belatedly, thank you!