Dometic tundra - compressor not cycling?

Good write up and follow up on your 12Vdc compressor refrigerator. The Danfross compressors can be replace by any confident HVAC tech and at the price that the varies makers of 12Vdc compressors refrigerators want for their units it would be worth while looking into.

I myself have had it with my absorption unit, it did its finnal death act two weeks ago and I'm not spending any more money on that money pit.

I'm looking at several different makes of 12Vdc compressor type refrigators all using Danfross compressors.

Just to let you guys know these 12Vdc Danfross compressors can be bought through Johnstone Supply.
Cat. #
B82-351...BD35F
B82-352.. BD50F
B14-369...101N020 12/24V DC Electronic unit

Nemo667 wrote:
Thanks for the follow up Sam. By chance you don't have a model with the top vent blocked with foam insulation do you? That's the only other thing i can think of that might have caused your problem.

I don't think mine is blocked. At least not entirely. BTW, it is still running strong with mid to upper 90's temps and high humidity all week here.

sf3291 wrote:
Posting as an update for any one else that may have a similar future problem.

I hooked up the 12V LED diagnostic light and started/stopped the fridge on two separate occasions now. No faults indicated and it cools right down. I'm leaving the LED connected and will let the fridge run through the week, expecting outside air temps to be warm and humid (temps in the 90's this week with that wonderful east coast humidity). I've also let it run on 12V and 120V, no issues and the batteries (2 Trojan 6V wet cells and 220W of solar) have never been low enough to trigger the low voltage fault to prevent compressor starts.

Since I did remove the fridge and re-installed, I'm wondering if my ground wire was ultimately at fault. Good enough to start the fan, but not good enough to start the compressor. Of course, I didn't have the diagnostic LED hooked up. Making/breaking electrical connections a couple of times is the only thing I can point to that is different.

Thanks for the follow up Sam. By chance you don't have a model with the top vent blocked with foam insulation do you? That's the only other thing i can think of that might have caused your problem.

Posting as an update for any one else that may have a similar future problem.

I hooked up the 12V LED diagnostic light and started/stopped the fridge on two separate occasions now. No faults indicated and it cools right down. I'm leaving the LED connected and will let the fridge run through the week, expecting outside air temps to be warm and humid (temps in the 90's this week with that wonderful east coast humidity). I've also let it run on 12V and 120V, no issues and the batteries (2 Trojan 6V wet cells and 220W of solar) have never been low enough to trigger the low voltage fault to prevent compressor starts.

Since I did remove the fridge and re-installed, I'm wondering if my ground wire was ultimately at fault. Good enough to start the fan, but not good enough to start the compressor. Of course, I didn't have the diagnostic LED hooked up. Making/breaking electrical connections a couple of times is the only thing I can point to that is different.

Well, the strangest of things is going on...

On arriving home today after work, I walk past the TC and hear the fridge running. Hmmm, I thought I turned it off and pulled the fuse? It also sounds like more than just the fan is running. Sure enough, I reach inside the fridge and put my hand on the evaporator (freezer) portion and there is frost. I'll be...

All this after reading up a bunch on the Danfoss 35 and 50 compressors (mine is the 35 as would be virtually all TC sized fridges). Seems like common experience is that this compressor is expected to last 20 years or more, but the electronic controls, maybe not. So, I found as cheap of a replacement controller as I could find from a place that also sells a pre-fab 12V LED with female spades to hook in and read controller diagnostics.

Since I'm not going anywhere in the next two weeks, I shut the fridge off and pulled the fuse. New controller will be here tomorrow night and by the weekend, I'll try it again with the old controller and diagnostic LED installed. If it works, it works. I'll just hold on to the spare controller despite the expense.

Oh, and I from what I gathered, the 277 Ohm resistor on the ckt card that I got for $11 would plug into the lowest spade terminal on the main ckt card to add resistance in the compressor ckt. Depending on the resistance, you can control the compressor speed from something like 2000-3500 rpm. No resistor = 2000 rpm. 277 Ohms = 2500 rpm. Etc. There are kits out there to put in manual rheostats or automatic speed control so that your system cools down quickly and then runs the compressor at a low speed for longer periods of time with the thought being lower speed over longer duration vice higher speeds for shorter duration will result in lower energy consumption and higher service life. Since I had no resistor in the first place...I'm thinking I'll keep it that way. Just means the fridge would take longer too cool down at 2000 rpm vice a higher speed.

Well, not so fast. Next to the main circuit card in this picture is what the company sent me.

The packaging for what the company sent me says R101021 Resistor Card 277 Ohms

In the owner's manual/installation manual for the fridge, they show a resistor in line from the main circuit board to the thermostat. I never found one after tearing into the fridge.

The guy I spoke to on the phone did describe the card as going near the bottom of the spade terminals...but I have no idea how I'd use this little resistor card.

Guess I'm going camping with an ice chest this weekend.

Yes that is the one. I hope that does it for you.

Paul,

Is this the circuit card you ended up replacing?



ckt card



Tearing in to mine, this is the only card I could find...essentially the terminal board that all of the female spade connectors for power, fan, t-stat, etc connect into.

It is under the black box cover to the left of the compressor in this photo here:

compressor view



I certainly hope that card pictured is the one they are sending me. As you can see mine is also plumbed for a 2 or 3 way fridge and the propane lines make it awful tight to get in there. I ended up having to remove the fridge and set it in the aisle. And as luck would have it...the fridge isn't moving any further without either ripping off the plumbing to the evaporator coils inside the fridge or removing the door frame. Sheesh.

sf3291 wrote:

Paul V wrote:
I had an electrical part fail on my 2006 Tundra fridge after about two years. I called the manufacture and they had me check to see if the fan was working which it was, then he had me check to see if the compressor was hot or cool, it was cool which means there is a problem, it should be warm to the touch.
They sent me out a new board that I replaced in a few minutes and it has been good ever since.
I wish I could be more help as far as names or models for the unit that was replaced.
Every trip I make and I turn the fridge on the day before I have my fingers crossed that it will fire up. Other than that it has been a great fridge.
Have you contacted Bob at Outfitter, he might have some info on who to contact.

Paul,

Thanks for the background. Hopefully it was the exact help I needed.

I ended up calling Dometic Marine since they list the tundra as a marine application. They refered me to a company called AAP at 804-633-9454 located in Milford VA. Talked to a gentelman there who said that most cases where the fan comes on but the compressor doesn't, it is the cirucit card you described. The card is the "speed control" card for the compressor. $11 for the card, it will be shipped tomorrow and I should have Friday evening since they are only 60 miles or so down the road from me (but one hell of a pain to drive down and pick up myself with the traffice we have around here.).

Fingers crossed that it is that card.

Sam

Thanks for the contact info on the circuit board. I will likely order one as a spare even though i haven't had any trouble with mine. The other thing you might check is the fuse in circuit panel under the dinette table. Although it still should have come on with shore power plugged in anyway. ...just a thought. Let us know if the circuit board does the trick. Good luck :B

Sam, I hope that fixes the problem.
Keep us updated.