Fridge won't cool below 50F on 120V

[Shibre]

Hello,

Hopefully this isn't something that has been covered thoroughly but I haven't been able to find anything via searches (here or online) other than if 120v doesn't work at all.

Basically, my fridge is a Dometic RM4223 in a popup camper. It's worked great until recently. LP still works exceptionally well but the 120v won't cool past about 50F. I have 120v at the socket and there's plenty of heat coming out of the back of the fridge. The area it's venting is clearly ventilated with no blockages of any kind.

The fridge has had plenty of time (days to weeks) to defrost in between camping trips so I feel that's not an issue.

Any ideas why the fridge isn't getting cold enough on electric?

[red31]

Shibre,

the parts lists doc shows the 120vAC specs on page 2
RM4223 parts list

Measure the temp as directed!

taller chimneys work better than shorter.

Check the install manual you posted, esp the minimum measurements on the back. Adding a baffle between the upper and lower vents may be need to help the convection move over the upper fins. Lots of folks have added baffling @ https://www.popupportal.com/forums/refrigerators-and-coolers.78/ , directing air to the upper fins and adding a 12v fan can help these fridges as they do not come with them generally in PUs.

[dougrainer]

That type Thermometer is USELESS. They are NOT that accurate. Get a Digital Thermometer and place it in a glass of water that has been in the refer for 24 hours on Max cool. Doug

PS, The fact you stated 20 degrees and using that thermometer shows how inaccurate it is. BY about 10 degrees.


https://www.homedepot.com/pep/Digital-Pocket-Thermometer-DT130/301397537?mtc=Shopping-BA-F_HDH-G-D29...

[doxiemom11]

What are the outside temps where you are? Are you sitting so the sun is shining on the frig side of your rv ? Are your cooling fans for the frig vent still operational? We have had this a few times, but one of the above was the cause. Once corrected the frig again cooled as it should.

[Shibre]

The preview of my post looked good but if my pic & link didn't work:

https://i5.walmartimages.com/asr/c472b4a6-0ec5-4132-a38c-3e73864a6ff9_1.1b5ed33d9c19568ca6d2ad80103559ab.jpeg?odnWidth=612&odnHeight=612&odnBg=ffffff

https://www.manualslib.com/manual/472015/Dometic-Rm-4223.html?page=8#manual

[Shibre]

I have one of these sitting on the main shelf:

I'll try with the water - that makes sense. On LP, this holds rather steady at around 32-34 on that thermometer leading me to believe there aren't any issues with the thermistor or door seal.

Yes, being a pop-pup it has the upper and lower sections. We've had it for about 2 years and this is the first we've had this issue. The current vents seem rather open but there does seem to be a lot of heat coming out of there. How would I improve this beyond just cutting more holes in the vent? Looking through the manual, I don't see any fan - nor have I heard one. It only appears to have cooling fins. ***Link Removed***

Thanks again for your help. When I get back Sunday I'll see how it does using the water test.

[dougrainer]

Shibre wrote:
Thank you for the suggestions.
If it helps to narrow things down, yesterday I turned the temperature knob to 0 (click) and then back to 7, the coldest setting. By morning it was at 20°F but by this evening it's back to 50°F.

Forgive my ignorance but which 'element' am I measuring for ohms and amp draw?
At the outlet, I'm getting 121.9V

You need to post what type Thermometer you are using. The ONLY way to test refer temp is to install a 8 oz cup of water on the shelf below the Evap fins and after 24 hours on 7, then test the water temp. NO RV REFER WILL GET TO 20 DEGREES IN THE LOWER SECTION. So, your temp test is suspect. The freezer will get below 10 degrees. What is the temp on LP? Also, in a Pop Up. I assume you have a Lower and upper vent doors on the outside. Pop Ups are notorious for having inadequate venting and baffling for correct Heat removal. This is a OEM caused problem not a refer problem. If the refer gets to that 20 on 120, your 120 system is OK. Ventilation will be your problem to fix. Most Pop Ups the refer has a 12 volt cooling fan on the back side of the refer cooling unit to help move air up and out the upper door. Doug

[Shibre]

Thank you for the suggestions.
If it helps to narrow things down, yesterday I turned the temperature knob to 0 (click) and then back to 7, the coldest setting. By morning it was at 20°F but by this evening it's back to 50°F.

Forgive my ignorance but which 'element' am I measuring for ohms and amp draw?
At the outlet, I'm getting 121.9V

[opnspaces]

So Doug,
Since the refrigerator is cooling to 50 would that rule out tests 1 and two?? If so then it sounds like only #3 low voltage is left.

OP, are you able to put a meter on the 120v outlet and see what it reads?

Are you able to run a long extension cord from a different outlet in the house and see of the refrigerator cools better?

[dougrainer]

You need to OHM check the 120 element, which should be about 60 to 75 OHM's depending on the wattage. BUT, ANY resistance other than OPEN the 120 element is Good. They do NOT operate anything under 100%. Either good or bad. The quicker way if you have a clamp on AMP meter is to clamp 1 wire of the 120 element and see the amp draw. From about 1.4 to 2.6 depending on the wattage rating. But, ANY amp draw will show it is good. LAST, The LINE voltage is critical on 120 volts. Below 115 volts, the Element will not get hot enough. Test the Line Voltage with a Digital multimeter AT the receptacle the refer is plugged into. Doug