Frig and furnace issues

[KRob]

My refrigerator and furnace stop working. I have a 2018 Thor hurricane 29M with an RV fridge. This is a 12 V problem. Other 12 V systems are working. When I plug into shore power, the refrigerator and furnace get no power at all. This is sporadic over the past three months. One clue is the problems started after new house batteries were installed, but I can’t find the problem there. Sometimes both work for two days and then I wake up and they’re not working. RV tech couldn’t find the problem, eventually said they found a problem in a ground wire under the kitchen drawer. Both systems worked for 2 days, but overnight (while using furnace, plugged into 50 amp) it happened again. Woke up to both dead as a door nail. It’s not fuses. It is sporadic. Every Wire I’ve looked at under the drawers near the fridge, around the fuse panel under the bed, and outside ( of the refrigerator) look fine. Ideas???? Anyone else have this problem and find a solution?

[cavie]

The fridge, furnace, wh, A/C and others use the same 12-volt circuit for control wiring. If it all worked before you changed the house batteries that is where I would start. You have a loose connection.

[KRob]

Well, I tried that and can’t find a problem with the batteries. And to be clear, water heater (on electric) is working. But the A/c and furnace control panel is dead, as is the frig. ��*♀️ I’ll try unhooking batteries, cleaning, testing and reconnecting again .

[16ACE27]

It's not a battery problem.

The Fridge and Furnace are usually wired to the same 12 VDC fuse from the distribution panel, commonly named "Appliances".

If these are the only two 12 VDC powered items that are not powered while plugged into SP, then regardless of battery condition, the Converter is supplying 12 VDC to the DC buss.

It sound like you have a bad wire connection between the fuse panel and where the Fridge and Furnace tie together into the + 12 VDC supply line. Others with is same issue have found that connection point to be bad.

Trace the wires so that next time you have this intermittent problem you know exactly where to go to put your multimeter leads to troubleshoot the issue as it is occurring.

[pneumatics]

I've had a few problems in past units where the common (white wire) makes intermittent contact. This is not the positive (+) wire. Manufacturers tend to bring several different device's white wires back to a common point and then either wire nut them together or bond to the frame of the vehicle somewhere. You could have several of these scattered around and these are the toughest to troubleshoot. Just a quick something else to look for.

[KRob]

Thank you!

[Boerne RV]

I have seen this exact issue and the cause was a loose fitting connection behind the fuse panel

[KRob]

It was indeed a bad wire.. the power wire to furnace and fridges. Thank you everyone for your help!!

[16ACE27]

Originally Posted by KRob

It was indeed a bad wire.. the power wire to furnace and fridges. Thank you everyone for your help!!

Good job finding it! The hardest problems to troubleshoot are intermittent problems.