Dometic Fridge

[erniebpk]

Hello Im new at trailering and need some help. I bought WW 5th wheel 2008, and my fridge is not always cold. Freezer works great. Ok, when i bought the trailer the fridge was cold. when i brought it home fridge cold warm. saw the hanging thermostate so i put it back on the last fin, where i thought it went. no luck. disconnected the thermostat and fridge works great. bought a new thermostat and put it in. fridge still worked fine, but when i got home from work fridge was warm. thought maybe i lost power, so i powered down and powered up. next morning fridge is great. same thing again when i got home. no power loss on AC. im using a standard electical extension. i tried moving the new thermostat up and down, but the fridge still giving me same issues. Can i just disconnect the thermostat or will that just be a temporary fix.

Please help, i want to enjoy my long awaited trailer.

Thanks,
Ernie
Chino, CA

[Old-Biscuit]

A short......

[erniebpk]

My fridge blew the 3 amp fuse again without me messing with anything. I had unplug the thermostat in the morning n the temp dropped to 45 degrees. What do you think that might be causing the fuse to blow n cut the power to the fridge

[Old-Biscuit]

Unplugging the thermistor (thermostat is built in) causes fridge to run continuously, non stop, no temp regulation. Leaving it unplugged the food section will start freezing up.

Take that 'new' thermistor while it is unplugged and place the tip in a glass of ice water...more ice than water. With ice water temp at 32*F measure the resistance at the end of leads. 8,000 to 10,000 ohms thermistor is GOOD.

So test that new thermistor.

[dougrainer]

A "quick" guess is a bad marginal cooling unit. You need to wire the 120 element direct to 120 power for 24 hours and see how the refer performs. 41 degrees is NOT good. Doug

[erniebpk]

More updates on my Dometic fridge. This morning i checked my fridge at 0530 hrs n it was at 70 degrees. I unplugged the thermostat from the back of the fridge inside the little black plastic box. At 1300 hrs the fridge is at 45 degrees. I just replaced the thermostat a week ago. What do u think the problem is?

Ernie.

[Old-Biscuit]

erniebpk wrote:
How do i fix a draft problem if i have one and the insufient air flow problem?

As a test.......

Stick a big box fan next to lower vent opening (vent removed) blowing air into fridge outside compartment then check temps Am and again afternoon.

IF fridge temps remain low then you need to install a couple of 12V DC pan-cake fans in the upper area just below upper vent.

If temps still vary....low to high. Probably blockage is occurring in cooling unit

[erniebpk]

How do i fix a draft problem if i have one and the insufient air flow problem?

[Old-Biscuit]

Moving the 'thermistor' will NOT correct a 40*F change in food section temps (only good for 6*-8*F change)

Overnight/early morning......temp 41*F but come late afternoon when it's hot outside temp goes up to 80*F.
You have a 'draft' problem...insufficient air flow across cooling unit from lower vent thru upper vent
OR your cooling unit is experiencing blockage inside cooling unit

[erniebpk]

Update on my fridge. After fixing everything i checked the fridge this morning at 0900 CA time and the fridge was at 41 degrees. CA time. Today at 1500 hours the fridge is now at 80 degrees. Its about 90 degrees and the tralier side of the fridge is partially in the sun. I have about 4 coke cans inside the fridge to use as cold reference. I moved the thermonstate down about a half inch or less to see if the. Fridge would get a little colder. Going to try and move it back up to where it was.

[dougrainer]

Sloop Smitten wrote:

The Freezer has nothing to do with the temp Thermister.

Since the refirgerator fins are cooled by the freezer the thermistor has everything to do with the freezer. Once the thermistor senses a certain temperatue in the frig it cuts power to the freezer to maintain the frig temperature. Temperatures in the frig are dependent on the temp in the freezer.

From a RV tech with 35 years experience. There are 2 sections of a RV absorbsion Cooling unit. The Top section tubes which is the freezer which is the FIRST section of tubes that get sub cold. Then the tubes go down a few more inches and contac the lower section where the Evap fins are. THAT section is controlled by the Tstat. This is one thing, novices do NOT understand especially when they purchase a used RV. The seller has the refer ON, and shows how cold the freezer is and the inexperienced buyer assumes the refer is functioning. BUT, a BAD cooling unit will Freeze the freezer but not the lower section, and then the novice finds out he was had to the tune of over a $1000 to fix the refer. The evap fins will be 10 degrees cooler than the refer. So, if the refer is 36 degrees the fins are 26 degrees and THAT temp is what the tstat responds too.
Doug

[Old-Biscuit]

erniebpk wrote:
Ok. The circuit breaker was tripped. After reseting it the circuit breaker the fridge returned to AC mode and the gas turned off.
Why do u think the circuit breaker tripped n the 3 amp fuse blew?
Oh ya. I checked the two red wires on the heat stack and there was 12 volt power to both sides.

Thanks again for the help.

Ernie.

Prior to the breaker tripping/fuse blowing out....where you messing around with anything?

The AC circuit breaker would trip due to overload (probably on a 15A CB)
so for some reason? the CB sensed excessive amp draw......usually the 5A fuse on fridge control module will blow if the electric element was shorted.

The 3A fuse on fridge control module is for the DC circuits....

So where you messing around with the wiring?

Those 2 red wires on on stack....they go to the stack temp sensor and would lose 12V DC IF the sensor had tripped from overheating.

With fridge ON and in 'Auto'.....the fridge will use electric heater when AC Power is available. IF no AC power then it will auto swap to gas operation. Swaps back to electric when AC power becomes available again. Taking it out of 'auto' places it in gas operation mode only.

[erniebpk]

Ok. The circuit breaker was tripped. After reseting it the circuit breaker the fridge returned to AC mode and the gas turned off.
Why do u think the circuit breaker tripped n the 3 amp fuse blew?
Oh ya. I checked the two red wires on the heat stack and there was 12 volt power to both sides.

Thanks again for the help.

Ernie.

[John_Wayne]

OK Erine you frig. on Elec. uses 12 volt and 120 volt. Do you have a test meter? There should be a 120 volt plug in the frig. area outside when the outside door is off. Plug a lamp into the plug if you don't have a meter, do you have power at the plug? If not could be a breaker tripped or a tripped gfi. (usually at an inside plug). If you have 120 it could be the heating element is bad. Next to the chimney for the frig. just above the gas flame area you should see two wires if you have a meter you can runs continuity check on these wires to make sure the heating element is not burned out.
Then with a test light or meter check for 12 volt at the rear of the frig.

[erniebpk]

Hello everyone. First of all i would like everybody who gave me there advance. This web site is a blessing. Thank all of you.

Ok, looks like the electrical went out on my fridge. The fridge light went out. The 3 amp fuse blew. I replaced the fuse but now my fridge will not turn on with AC. The setting on the fridge is set for auto. I turned the gas on to see if the fridge gets cold. I also put the thermometer back into its hold onto the last fin and with the thermometer sticking out a little from the plastic holder.
If it gets cold on gas what n how do i fix the electrical part?

Thanks
Ernie
Chino, CA.