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Muddypaws · 11-09-2012, 06:02 PM

When we got up this morning our Norcold was sitting at 48F.

It was running on AC. We transferred everything to another refer as fast as we could.

I switched it over to gas and it immediately started cooling down and was back to usable temps by the afternoon.

I went throught the on-board diagnostics and they indicated that the AC heaters 'did not open' and that the AC heater relay is stuck.

I'm thinking that the diagnostics may be misleading. If the relay failed wouldn't it cause the heaters to 'not open'? Or would two bad heaters perhaps cause the relay to appear 'stuck'?

Here's my questions:

Can one trust the on-board diagnostics?

Is there a way to test the heaters manually? Can a resistance reading tell me if they're bad or not? What would be a good resistance?

The board is a Norcold 628661. I've tried to find a Dinosaur replacement on their website without much luck, I have found references to them in other places, but nobody who actually sells one. Does Dinosaur make a replacement for this board? Has anybody replaced this board with a Dinosaur board?

Thanks,
Muddypaws

KIX · 11-09-2012, 06:08 PM

Disco the heater leads from the board. The resistance when new is 64
Hope this helps

RV Wizard · 11-10-2012, 02:24 AM

you can download the service manual here: iRV2 Forums - Files - Norcold 1200 LRIM Service Manual

Points in the relay can weld together even though the elements are good. The points open and of coarse there is amperage draw at the time and each time they open they arc. This causes pitting of the surface of the points, which causes a higher resistance, and eventually the surfaces are "stuck" or welded together from the amperage draw through the smaller area of conductible surface. Good luck and keep us posted.

paz · 11-11-2012, 06:28 AM

Another thing to check are the fuses on the circuit board. There is a 12V automotive-type fuse, which is obviously good since the fridge runs on LP; but there is also a glass 120V fuse.

Muddypaws · 11-11-2012, 05:35 PM

When we got home today I looked at the fuses and the A/C heaters. Everything was fine.

I cleaned all the contacts and put the board back in and started it up in AC mode. It seems to be working fine now.

The display did NOT show a NC code. Everything looked normal except the temprature. It's fairly likely that the diagnostic codes I read were there from a long time ago as well. I cleard all the old codes today.

Is it possible that a power surge or drop could cause temporary non-cooling? Our quiet little Lasko heater also went bonkers that morning.

In all our years of RV'in we've never had power surges and I've resisted the urge to put in a surge protector. Maybe it's time?