Reefer performance

[RedT]

Reefer Performance

Opinions solicited, please. Electronic control problem, cooling problem, normal condition?
Facts: Norcold Model NB22 (15 years old)
April 12, 2018 noted reefer temp 48 degrees, outside temp 80 degrees, windy conditions, temp setting increased from "7" to "9" (max). Operation changed from elec to gas, no change.

April 13, 2018 Early morning reefer temp 31 degrees, temp setting turned down to "7" Mode changed to Elec. No wind

Apr 14, 2018 Reefer temp at 4:30 AM 36 degrees at a #7 temp setting. Clnsidered this to be normal operation.

Next outing, May 10, 2018
Reefer turned on at 4:00 PM yesterday, OAT = 100 degrees. Reefer temp 36 degrees at 4:00 AM this morning. During travel to campground (gas operation) the reefer temp continued to climb. At 63 degrees in the box, a fan was placed in the back of the reefer compartment. Temp slowly began to decline. At 9:00 PM reefer temp was 50 degrees, was a windy day.

May 11, 2018 Reefer temp at 5:00 AM was 40 degrees, 39 degrees at 7:00 AM, 42 degrees at 10:30, (after meal prep) 42 degrees at 12:30, 41 degrees at 4:00 PM. Placed temp sensor next to room thermometer, and both read same. (Sensor accuracy verified)

June 14, 2018 Windy conditions. Altitude 7,500 feet. Outside temp 76 degrees. Reefer temperature at 8:30 PM was 38 degrees. Temp setting "9" (Max) Wind calm.

June 15, 2018
Reefer temp this morning was 28 degrees - outside temp was 54 degrees. Temp seting reduced to "7". Now at 12:30 PM, outside temp is 76 degrees, reefer temp is 33 degrees.
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[Ray,IN]

The one constant I noted was air movement/wind is involved when frig temp rises. By chance is the condensate drain tube sticking outside through the louvered door? This can cause a venturi effect to pull chilled air out of the frig. The end of the drain tube should be in the condensate catch pan(should always have some condensate inside that hasn't evaporated yet) near the boiler tube and heating elements to prevent cold/warm air transfer. There should also be a restricter button in the end of the condensate drain tube to prevent insects from crawling up the hose.

[Ray,IN]

Addendum to my initial reply; A huge factor that effects frig/freezer temperature is the frequency and length of time a door is open. Absorption refrigerators are slow to recover from anything that warms the interior. This is most often manifested by holding the door open while deciding what will be removed. This allows most of the chilled air to spill out, only to be replaced with ambient temperature air.

[RedT]

Originally Posted by Ray,IN

Addendum to my initial reply; A huge factor that effects frig/freezer temperature is the frequency and length of time a door is open. Absorption refrigerators are slow to recover from anything that warms the interior. This is most often manifested by holding the door open while deciding what will be removed. This allows most of the chilled air to spill out, only to be replaced with ambient temperature air.

As a First Sgt, you should know that SWMBO runs things around my coach - especially inside. Ain't no way I'm gonna tell her how long to leave the door open!

Seriously, I'm convinced this fridge, being 15 years old just needs a bit of help with the convection air flow. A couple fans on top should help a lot. At first I thought it might be the control panel.

[Ray,IN]

The best thing I have done to improve the performance of my Norcold 1200LRIM is; last year I installed an ARP 2.1(now superseded) unit(w/optional blower-type fan. Under somewhat controlled conditions(inside our RV garage during similar weather conditions) using the same frig settings, the ARP unit caused a temperature drop from 34° to 24°, boiler temperature lowered from nearly 400° to 238° during the 24 hours after the installation. Had to raise the temp setting by one to prevent freezing milk.
Yes i wrote a testimonial, because it does what the maker states.


Once I sat down with DW and explained how and why our absorption refrigerator works, she now realizes the importance of opening the doors to a minimum _most of the time.

[Steve Kiemele]

Originally Posted by Ray,IN

The one constant I noted was air movement/wind is involved when frig temp rises. By chance is the condensate drain tube sticking outside through the louvered door? This can cause a venturi effect to pull chilled air out of the frig. The end of the drain tube should be in the condensate catch pan(should always have some condensate inside that hasn't evaporated yet) near the boiler tube and heating elements to prevent cold/warm air transfer. There should also be a restricter button in the end of the condensate drain tube to prevent insects from crawling up the hose.

One thing to consider is that the Norcold goes into defrost mode “about” every 48 hours. If you check the fridge (lower compartment) temp during this period, you might think something is wrong.

Sun on the back side of the fridge is a problem. An auxiliary fan might help in this case.

I have noticed a consistent temperature rise while driving. I think that the coils do not vent well with a 60 mph wind down the side of the coach. I added an ARP fan and a manual switch to blow air into the outside compartment while traveling. If interested, I’ll send you the wiring diagram.

Your fridge “should” perform better on gas, assuming that the gas pressure is right and the burner is clean. My gas performance benefited from a regulator and burner replacement.

[Isaac-1]

If your refrigerator is slide mounted it may have/need fans in the outside duct to help exhaust heat. If the RV manufacturer installed them, then they may have worn out and died at some point in the last 15 years and simply need to be replaced.

[Lt Dan]

Good airflow over the rear coils on an absorption fridge is the key to cooling. I had the same issue with the one in our Itasca, it would cool well when parked, but temps would climb when going down the road. I determined that airflow along the side of the coach was creating a sort of vacuum that would keep air from entering the lower vent. A good set of fans inside the lower vent blowing air up into the rear cavity really helped. I was going to experiment with a couple of "air scoops" on the vent to help pull air in, but we traded the coach before I could try.

[Old-Biscuit]

NB22......


How about 'N822'


Service Manual
http://direct.bryantrv.com/docs2/doc...newnseries.pdf


Airflow is Critical for proper fridge operation ......
If fridge doesn't have OEM fan(s) then installing a couple up high will be beneficial
Up high fan will pull air in via lower vent up thru absorber tubes then push it across condenser fins and out upper vent