Community Forums

kjmort · 01-08-2013, 06:56 PM

My furnace would cycle properly once and run up to set temp and shut-off normally. The next time it called for heat it wouldn't start and according to the diagnostic led the light flashes 3 sec. pause and flash. etc. according to the book it is a limit switch/air flow. I reset the system and now it won't even come on once. It does nothing and the diagnostic light doesn't flash either. Anyone have any ideas what to check next.

"007" · 01-08-2013, 07:26 PM

Welcome to irv2.
See if this thread may help you out.

kjmort · 01-08-2013, 07:51 PM

I took the outside panel off and touched some of the wires and the furnace started right up and cycled perfectly and shut down normally. So what is the best way to locate the short. If I don't touch anything it works but that is only a temporary solution until morning when I can investigate more. But would appreciate any suggestions on locating the short. Thanks karol

RV Wizard · 01-09-2013, 02:49 AM

Karol, you actually have an intermittent open circuit condition, not a short. A short circuit is excessive current and usually will trip an over current protection device. Most of the time the problems I find are a bad connection of the molex connector to the control board. You can pull this board out some, remove the connector clean the contact points with a pencil eraser and/or electrical contact cleaner and make certain the pins in the connector are clean and will make a tight fit onto the board. This will usually solve your problem. If not, check the rest of the electrical connections at the various terminals on the furnace. Good luck and keep us posted.

kjmort · 01-10-2013, 06:54 AM

Mike I would like to tell you thanks so much for your advice. I cleaned the molex coupling and made sure the connection was tight but that did not fix the issue. I continued on with all the other connections on the circuit board side and the connection feeding the power to the furnace. Took my time and made sure all connections were cleaned and when reconnected made sure all were tight. After putting it all back together hit the switch and it started right up just like it was new. Thanks so much. I am now a happy camper again. Karol