Dometic 8000 series on 12v

[RedFrame]

We have the above which is working on 240v and Gas to the standard an 8000 series does, but has been loosing temperature when on AES while driving and when testing while static gives the Red error light/beeping if forced to 12v via the control panel while the engine is running at idle.

While forced to 12v with the engine idling, putting a multimeter across the 12v Heating element supply shows the voltage oscillating between 0v and 14v approx. every 1/2 - 1 second and I can hear a relay switching in and out, I think from the PCB rather than the heating element. When disconnected the Heating element supply is a steady 14v (ish).

Has anyone experienced this, or have knowledge of a soloution?

Cheers
Bannock, Red and Chris.

 

[DP+JAY]

Sounds like either the heating element or a bad connection somewhere. Have you checked the element for resistance?
DP

 

[Fletton]

Watchin with interest... But not sure what you mean when you say "steady 14" when disconnected... What from where?

 

[RedFrame]

Sounds like either the heating element or a bad connection somewhere. Have you checked the element for resistance?
DP

No, can you tell me how I would check the resistance...?

Watchin with interest... But not sure what you mean when you say "steady 14" when disconnected... What from where?

There is a connector bloc that provides separate power to both the fridge controls (all the time) and 12v Heating Element when engine is running, when the bloc is disconnected the 12v Heating Element supply is stable.

Cheers
Red, Chris and Bannock

 

[DP+JAY]

You need to disconnect the 12v heater element wires & measure the resistance using a meter set to ohms, though it's sounding more like a dry joint/bad connection.
DP

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[RedFrame]

You need to disconnect the 12v heater element wires & measure the resistance using a meter set to ohms, though it's sounding more like a dry joint/bad connection.
DP

OK, will do tomorrow morning and report back, thanks for your assistance.

Cheers
Bannock, Chris and Red.

 

[dave newell]

Poor earth connection.

D.

 

[RedFrame]

You need to disconnect the 12v heater element wires & measure the resistance using a meter set to ohms, though it's sounding more like a dry joint/bad connection.
DP

OK, so I managed to get to it just now and tested the resistance as described above, it's zero, I also switched it to continuity and got a beep out of the multimeter, I'm guessing there should be some resistance?

Cheers
Red.

 

[Lenny HB]

OK, so I managed to get to it just now and tested the resistance as described above, it's zero, I also switched it to continuity and got a beep out of the multimeter, I'm guessing there should be some resistance?

Cheers
Red.

Sounds like it's OK it is very low resistance as depending on model they draw up to 15 amps.

 

[jockaneezer]

Does your van have the Reich control box fitted to it ? My '05 Burstner fridge failed on 12 volt and I had the "oscillating" voltage scenario when I checked with my multimeter. The circuitry in the Reich isn't up to it, cost around £300 to get repaired by Apuljak Engineering, a new box was around a grand. Hope your's is something simpler.

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[RedFrame]

After Lenny's post I've been and re-checked and at the lowest setting it is showing 1.2 Ohm.

I've now also re-seated all the connectors on the rear pcb, and the earth's to the back of the fridge no change. It constantly switches between 12v and Gas when on AES with no error and lights up red and beeps if 12v is manually selected (the engine is running in both scenarios).

I don't think it's a reich, it's one of these... http://rover.ebay.com/rover/1/710-5...0001&campid=5338547443&icep_item=303246099132

Is there a way to check for a bad earth, I'm guessing this would be on the control wire to the relay?

Cheers
Red.