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68 TWind · 07-20-2012, 04:05 PM

This morning I started my year old Dometic fridge on LP to make sure it would light and to start cooling down the unit for a trip this weekend. It fired right up and in a couple of hours the temp was falling nicely. Since I had the trailer plugged into shore power after a couple of hours I switched over to 120V. A little while ago I went out to start putting food in the unit and I found that the temp was back up and the fridge was not cooling. I checked the breaker and the outlet in the back where the fridge is plugged, all was fine. I would appreciate any advise on trouble shooting the 120V mode for the Dometic.

**DKB_SATX** · 07-20-2012, 04:33 PM

Is it the original fridge with manual controls and no 12V control board?

If so, did you verify that all of the controls are set properly for 120V?

Verify that 120V is available at the fridge outlet and that it's securely plugged in.

Test for continuity across the 120V heating element.

68 TWind · 07-20-2012, 04:42 PM

It is new. I bought it last year. The last time I used the 120v was in May and everything was fine. It is cooling just fine on LP.

snakecharmer · 07-20-2012, 04:54 PM

Is the "Check" light coming on?

Make sure you didn't accidentally activate the "gas" button on your controls area.

I did that once and then wondered why it wasn't cooling on A/C

lewster · 07-20-2012, 05:51 PM

Quote:

Originally Posted by 68 TWind

This morning I started my year old Dometic fridge on LP to make sure it would light and to start cooling down the unit for a trip this weekend. It fired right up and in a couple of hours the temp was falling nicely. Since I had the trailer plugged into shore power after a couple of hours I switched over to 120V. A little while ago I went out to start putting food in the unit and I found that the temp was back up and the fridge was not cooling. I checked the breaker and the outlet in the back where the fridge is plugged, all was fine. I would appreciate any advise on trouble shooting the 120V mode for the Dometic.

First, it is AC, not A/C (which is usually shorthand for air conditioner

). If it is a newer Dometic, there will be a series of fuses in the rear, near the control board. You should check them, as the 120VAC that runs thru the control board is also fused there. Also, if you have access to an amp meter with an induction clamp, you can see if the heating element is drawing anything by clamping around the wire (either one) that is coming from the board to the element.

Further, you can locate the 2 output terminals at the bottom of the board (terminal #'s vary with the model of fridge, but usually at the bottom right of the termninals) to see is 120VAC is coming out of the board to the element. If no voltage and the fuse is good, along with checking the outlet to the fridge, either the heating element is bad or the board is bad.

You can check the heating element by doing an ohms test after removing the leads from the board, IIRC, Dometic elements are usually around 45 ohms, but they also vary according to model.

Let me know if you have any other questions.

68 TWind · 07-20-2012, 06:50 PM

Thanks Lewster. I will try and give it a good check when we get to the campground. The outlet was the first thing I checked and it is fine. I checked the model and it is a RM2510. Hopefully I will be able to access the wires I need to check from the small access hatch. I spent several days working on this when I built it in and I really hate to think about what all would be involved in removing it. Just checked the temp and is down to 31 on LP so we will be in good shape for this trip. I'll keep you posted on what I find but it will be next week before I will have time to check it.

TG Twinkie · 07-20-2012, 07:59 PM

The electric side has a separate thermostat. Do you have it turned up? Mine has a 3 position switch: gas-off-electric. Make sure you select electric and not off.

snakecharmer · 07-20-2012, 09:17 PM

Dang it, lewster, I should have known that, having recently attended your highly informative seminar at the Resto Rally!

I remember Ohm's law, but I can't keep AC-A/C straight!

Anyway, thanks for the correction.

I feel very fortunate to know that you are out there, ready, willing and able to share your extensive knowledge and experience with us.

You're a real asset to our community!

Thank you, thank you, thank you!

lewster · 07-21-2012, 04:36 PM

Quote:

Originally Posted by TG Twinkie

The electric side has a separate thermostat. Do you have it turned up? Mine has a 3 position switch: gas-off-electric. Make sure you select electric and not off.

Newer models of RV type refrigerators (unless you are referring to the Dometic NDA-1402) do not use a thermostat, rather they have a single 'thermistor' that is located on the cooling fins inside the unit at the upper right section, generally on the second fin about 3/4 of the distance up from the bottom of the fin.

The control board reads the changing resistance generated from this device (measured in ohms and variable with the internal box temps) to keep track of the interior fridge temps and regulate the operation of the electric element or the LP burner. The interior temperature is set within a certain range by the adjustable control (on Dometics, either numbers 1-5 or no numbers for the fully automatic units)

If the unit operates properly on LP, the thermistor is in working order and can be excluded in the trouble shooting regimen.

lewster · 07-21-2012, 04:37 PM

Quote:

Originally Posted by snakecharmer

Dang it, lewster, I should have known that, having recently attended your highly informative seminar at the Resto Rally!

I remember Ohm's law, but I can't keep AC-A/C straight!

Anyway, thanks for the correction.

I feel very fortunate to know that you are out there, ready, willing and able to share your extensive knowledge and experience with us.

You're a real asset to our community!

Thank you, thank you, thank you!

My pleasure!