Poor Refrigerator Performance - Fan Thermister Test & Drain Hose Routing?

[jadams]

We experienced some lackluster refrigerator performance on our last outing.

In preparation (thanks for all the tips found on the forum! ):

--fridge cooled down to below 40 degrees on AC power (24) hours prior to departure,
--fridge loaded with solid freezer blocks and chilled beverages on departure,
--drove 2 hours, arrived at 8:30pm,
--turned fridge on LP, loaded with cold food from cooler, freezer packs moved to freezer

Fridge held cold temp until late morning the day after our arrival. Then maintained 50-58 degrees. This was at the coldest setting. Interior humidity was high. Lots of moisture.

When returning home, upon inspection, interior and exterior workings of fridge were really clean and all door seals are good. I cleaned even more.

I tested the interior thermistor and got a proper ohm reading (fantastic instructional video- MY RV Works at 30:00 https://youtu.be/IT_5HGe4q-k)

I’m perplexed by the exterior fan, because I have never heard it run. There’s no on/off switch like I see other trailers possess. So I imagine it's controlled by a thermistor. Has anyone tested this? It’s been in the mid 90s all week.

The drain hose exited the rear of the fridge and looped up a full 12” and traveled down another +18” to the drain hole. Creating a long U trap. I rerouted the hose and created a more modest 2” U trap hoping I’ll get more water to drain from the interior of the fridge to reduce humidity, but I could be wrong.

I also saw the drain hose protective cover was blocked partially by debris possibly reducing drainage.

I’ve now had the fridge running for over 48 hours on AC power and it’s been below 40 degrees for 48 hours in 90 degree + daytime heat.

Clearly the cooling unit is good under AC power. Next test is on LP for 48 hours.

I have a small battery powered interior fan on the way (thanks to everyone suggesting this on another recent thread! )

[padlin]

On my RMD8555 (6 cu ft) the thermistor is rated way too high, something like 150 degrees so it never goes on on mine either. A workaround is to clip into the leads and put in your own switch to bypass the switch when you want to. I did that for my RML8555 but have not needed it on the RMD. The hard part is remembering it's on.

Might check the water column reading for the fridge, I bumped mine up a bit.

I can search up the actual figures for the above if needed. It's been a good while since I played with the fridge.

[padlin]

I changed my regulator out looking for a fix, the new one worked great and had a WC of 12" as opposed to the 11" that is recommended. I split the difference to 11.5".

[jadams]

Fantastic suggestions Bob!

150 degrees, not even useful.

I haven't come across information regarding the water column. Please elaborate if you're able to. This is all a new DIY adventure for me. Thank you.

[steve dunham]

1) On one our previous trailers we had an exterior 12 VDC refrigerator fan
The fan was controlled by an on & off switch located inside the trailer and by a klikon thermostat attached to the fins on the back of the refrigerator ( Fixed setting 90 deg F)
Fan worked well in hot weather and you could definitely hear it when running so I added isolation mounts

2) The refrigerator in our Scamp would not cool properly ( 48 hours of precool , temp still above 50 deg F ) Cause was low gas pressure at refrigerator - reset gas pressure to 11.5 WC and all was well . Temps dropped below 40 deg F when running on propane.

[padlin]

If can do a search using the google search option above and type in manometer.

Basically you're measuring the pressure out of the regulator at the device in question, in this case the fridge. There is an adjusting screw on the front of the regulator. Your fridge may have a test port, mine does. You tap into the test port with a manometer (about $40), turn on about 50% of the normal load, meaning start the hot water heater, then start the fridge and see what the measurement is. Adjust as necessary.

It's a little intimidating the 1st time you check/adjust it, but it's really no big deal.

What model fridge do you have?

[padlin]

Here's a thread on the fan switch and thermistor. Looks like the originals were 160F.

https://www.escapeforum.org/forums/f...fan-10157.html

[jadams]

Originally Posted by padlin

If can do a search using the google search option above and type in manometer.

Basically you're measuring the pressure out of the regulator at the device in question, in this case the fridge. There is an adjusting screw on the front of the regulator. Your fridge may have a test port, mine does. You tap into the test port with a manometer (about $40), turn on about 50% of the normal load, meaning start the hot water heater, then start the fridge and see what the measurement is. Adjust as necessary.

It's a little intimidating the 1st time you check/adjust it, but it's really no big deal.

What model fridge do you have?

Thank you for the additional explanation and info. Also, nice to know even though it feels intimidating it's doable. I'll get working on this.

I've got a Dometic RM2454 fridge.

[Rossue]

Had a similar experience last March: fridge cooled good on AC - not on propane. Soaking the orifice in alcohol for 10 minutes fixed it.

[Fun Pig]

I’m perplexed by the exterior fan, because I have never heard it run. There’s no on/off switch like I see other trailers possess. So I imagine it's controlled by a thermistor. Has anyone tested this? It’s been in the mid 90s all week.

The exterior fan is controlled by a thermistor on the top cooling tube (the one with fins). The fan has come on with outdoor temps as low as 70. The supplied fan was quite noisy. I just got finished pulling the refer and replacing it with a quiet one.

I was also mystified by the large loop in the drain hose which acts as a big P trap. I don't know why a drain hose from the refer needs a trap a all. Any ideas?

Alan

[padlin]

On my fridge, predecessor to yours, their was a water trap instead of the hose loop who's purpose we surmised was to keep cold air from being drawn out from the fridge. Water in said trap or loop would prevent such.

[Fun Pig]

That sounds like a reasonable explanation to me.