Atwood furnace issues

[Bnrc73]

2010 Montana 3400rl. Used up one propane tank coming down to Texas from Minnesota. Furnace worked fine. Shortly after switching to the new tank my furnace started acting up. When you start it up it works fine, pushing 85° air at the floor duct. It will cycle right once or twice, that’s when the trouble starts. It will not cycle off and the air temp at the floor declines to the low 60°. The fan will not stop. I did fill the empty tank and put it back into service, but nothing changed. The furnace does light properly and you can hear when the flame starts. Also when it starts failing inside you can hold your hand on the outside vent. The exhaust is warm but not as warm as I remember. I’ve got the RV Doctor coming Monday. If anyone has had similar issues I would appreciate hearing what your fix was.i might be able to do some DIY and save a little money. Sorry for the long post, but I figured the more detailed the better responses..thanks in advance.

[rnelan]

Unfortunately, I am very familiar with RV/Marine furnaces, so I will take a shot in the dark based on what you have written. That sounds like a over limit switch to me.. The furnace is getting too hot.. I'd like to hear if your mobile tech agrees later!

[Bnrc73]

Thanks. I’ll post the cure Monday.

[Bnrc73]

Many Mondays have past and my furnace is still not working right. RV Doctor set up a temporary thermostat thinking that could be it. Wrong. Finally got a cold spell so I could test the system. It cycles like it should. Here’s the symptoms, with a thermometer on the floor vent I set it to 72°.(64° in unit) first cycle, air is at 118°. Second cycle is at 101°. Next 4 cycles between 85° and 90°. By late night it’s only pushing air in the high 60s to low 70s. At this temp it doesn’t get the camper warm enough to shut off the thermostat. It’s not the high limit switch. Dr. Tells me a bad switch will keep it from lightning. Dr is coming again this week to dig into it a little more. Thinking of installing a new dinosaur control board. I’ll post back when I get this fixed. Glad it’s warm in Texas.

[Bnrc73]

RV doctor was back today. Installed a new Dinosaur control board and with this cold snap we hit here in Southeastern Texas, it’s working like new.

[jcurtis934]

Glad to hear it is fixed. When my furnace did that recently, it was a bad 30 psi crossover regulator and/Or the hose from the tank feeding the red beast. Same symptions as yours with smelly reduced heat coming out of the furnace exhaust port outside...BUT I could manually switch back to the other tank to restore service. And I didn't take time to figure out if one or both of the low costs parts were my issue. Both went in the trash.