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 > Looking for Dometic DMR702 service manual

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MalibuDave42

Colorado

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Joined: 09/13/2020

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Posted: 01/11/21 06:53am Link  |  Quote  |  Print  |  Notify Moderator

I'm not 100% sure I have solved my ambient temperature problem. But, I do feel I am gaining ground on it. Since I started this thread, I have learned\done this:

1. My electrode was bad. I replaced it.
2. Frost on my tank is two fold
A. If the ambient temperature is below ~35, propane can't vaporize quickly enough to provide gas for appliances to work correctly. In cold weather, never let your tank(s) get below 1/2.
B. Regulators on RVs (as with many things) are the cheapest the RV vendor could find. In other words, they go bad pretty quickly.
In my case, cold weather, bad\inefficient regulators - I replaced both tank regulators and the switch between the tanks with higher quality and increased flow rate rating.
3. In cold weather, the refrigerant can freeze. In summer, the refrigerant can't release the heat it removed from the fridge efficiently. The heat can't be released from the coils since the fridge is "inside of a low air circulation box" (aka built into the side of the camper)
A. For summer - increase air circulation by adding temperature controlled fans to get the hot air out. I added two low amperage fans: 1 to suck in the bottom vent; Another to blow air out at the top vent.
B. For winter - reduce air circulation (never remove all circulation). I added a shaped foam rubber "stopper" for the lowest louvre of the lower vent door. If the temp is going low, I push the stopper into the lourve to reduce air flow.
4. The inside-of-the-fridge temperature sensor (thermistor) can go bad. I replaced it with a aftermarket variable thermistor.

I hope this information helps you. As I mentioned, I am not 100% sure I've corrected the problem - time will tell. I sure know a lot more about RV fridges now :-)

dougrainer

Carrolton, Texas

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Joined: 06/11/2007

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Posted: 01/11/21 11:21am Link  |  Quote  |  Print  |  Notify Moderator

MalibuDave42 wrote:

I'm not 100% sure I have solved my ambient temperature problem. But, I do feel I am gaining ground on it. Since I started this thread, I have learned\done this:

1. My electrode was bad. I replaced it.
2. Frost on my tank is two fold
A. If the ambient temperature is below ~35, propane can't vaporize quickly enough to provide gas for appliances to work correctly. In cold weather, never let your tank(s) get below 1/2.
B. Regulators on RVs (as with many things) are the cheapest the RV vendor could find. In other words, they go bad pretty quickly.
In my case, cold weather, bad\inefficient regulators - I replaced both tank regulators and the switch between the tanks with higher quality and increased flow rate rating.
3. In cold weather, the refrigerant can freeze. In summer, the refrigerant can't release the heat it removed from the fridge efficiently. The heat can't be released from the coils since the fridge is "inside of a low air circulation box" (aka built into the side of the camper)
A. For summer - increase air circulation by adding temperature controlled fans to get the hot air out. I added two low amperage fans: 1 to suck in the bottom vent; Another to blow air out at the top vent.
B. For winter - reduce air circulation (never remove all circulation). I added a shaped foam rubber "stopper" for the lowest louvre of the lower vent door. If the temp is going low, I push the stopper into the lourve to reduce air flow.
4. The inside-of-the-fridge temperature sensor (thermistor) can go bad. I replaced it with a aftermarket variable thermistor.

I hope this information helps you. As I mentioned, I am not 100% sure I've corrected the problem - time will tell. I sure know a lot more about RV fridges now :-)


OK lets take some misinformation first.
1. LP will vaporize down to -42 degrees. YES, a LOW LP fluid level will hamper vaporization, so YES, keep them full in cold weather
2. DO NOT restrict the air flow in freezing temps. Just add a 60 watt light bulb to the rear outside area of the refer
3. BOTH tank regulators????????????????????? I have NEVER seen a RV LP system with 2 LP regulators. Never in 41 years as a Tech. They have 1 regulator with a dual Auto switchover. Now, some 5th wheels have dual/triple tanks, with 2 tanks on 1 side and the 2nd or third on the opposite side. The hose between those types have a HI PRESSURE regulator to prevent a BAD accident if that hose springs a leak and would spew hi pressure/volume of LP. That hi pressure reg reduces the LP pressure from the tank to the other side. Usually the PSI (NOT the WC LP RV working pressure) is around 150 PSI out of a non regulated LP tank. This Reg drops it to about 30 PSI.
4. While they do use the Cheapest LP regulators, the main enemy of any regulator is, liquid LP. Liquid LP can be easily introduced if the LP cylinder is somehow overfilled. The auto shut offs do not always stop extra liquid when filling. Having a full cylinder whether on DOT tanks or ASME motorhome tanks, can allow the Liquid to slosh in transit and allow liquid to get into the regulator and either causing it to leak of cause pressure problems.
5. It appears that you had multiple problems and you slogged thru and fixed the various problems. Doug

sdtravis

Encinitas

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Joined: 12/30/2020

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Posted: 01/11/21 03:23pm Link  |  Quote  |  Print  |  Notify Moderator

MalibuDave42 wrote:

I'm not 100% sure I have solved my ambient temperature problem. But, I do feel I am gaining ground on it. Since I started this thread, I have learned\done this:

1. My electrode was bad. I replaced it.
2. Frost on my tank is two fold
A. If the ambient temperature is below ~35, propane can't vaporize quickly enough to provide gas for appliances to work correctly. In cold weather, never let your tank(s) get below 1/2.
B. Regulators on RVs (as with many things) are the cheapest the RV vendor could find. In other words, they go bad pretty quickly.
In my case, cold weather, bad\inefficient regulators - I replaced both tank regulators and the switch between the tanks with higher quality and increased flow rate rating.
3. In cold weather, the refrigerant can freeze. In summer, the refrigerant can't release the heat it removed from the fridge efficiently. The heat can't be released from the coils since the fridge is "inside of a low air circulation box" (aka built into the side of the camper)
A. For summer - increase air circulation by adding temperature controlled fans to get the hot air out. I added two low amperage fans: 1 to suck in the bottom vent; Another to blow air out at the top vent.
B. For winter - reduce air circulation (never remove all circulation). I added a shaped foam rubber "stopper" for the lowest louvre of the lower vent door. If the temp is going low, I push the stopper into the lourve to reduce air flow.
4. The inside-of-the-fridge temperature sensor (thermistor) can go bad. I replaced it with a aftermarket variable thermistor.

I hope this information helps you. As I mentioned, I am not 100% sure I've corrected the problem - time will tell. I sure know a lot more about RV fridges now :-)


I'm with you about knowing a lot more about these refrigerators than I bargained for. My unit DMR702 unit is brand spanking new and I can't figure this out. I'm out here in san diego with 43 degree night time weather and this refer is still shutting down in the middle of the night (see my original https://www.rv.net/forum/index.cfm/fusea........d/tid/30185661/srt/pa/pging/1/page/1.cfmpost here).

As other posts have reminded me, this version of the Dometic fridge was fully outsourced and is known for quirky issues. I'd be curious to find out if you solved the issue on your end.

sdtravis

Encinitas

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Joined: 12/30/2020

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Posted: 01/12/21 02:41pm Link  |  Quote  |  Print  |  Notify Moderator

An update that adds to some of the mystery. I placed several cameras to get a better view of what happens when the fridge shuts down in the middle of the night and have a few interesting findings.

From the camera I put inside the exterior compartment, the fridge is running perfectly with plenty of flame then a loud click is heard (solenoid valve shutting) and the flame shuts down. There is NO attempt to relight the flame.

Two seconds later, the fridge starts displaying the error lights on the front panel.

If I close the valve on the propane or blow out the flame, the fridge automatically goes through 3 attempts at relight. In this instance the fridge is shutting itself down and not relighting which means its not likely to be an LP supply issue.

MalibuDave42

Colorado

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Joined: 09/13/2020

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Posted: 01/14/21 04:38pm Link  |  Quote  |  Print  |  Notify Moderator

sdtravis - Love your idea of a camera..

I read your old post. IMO, it's your regulator(s). This is a cheap fix. At minimum, a little money well spent for a far better, longer lasting product. At best, it cures your situation. (My trusted propane guy is on call for several local RV dealers.. he's says he gets many calls for brand new rigs -- bad regulators)

It also could be the igniter throwing an error. Replacing it is cheap and easy.

Also note: I see that Old_Biscuit replied to your old post.. take his word as gospel. He knows his stuff.

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