Furnace and fan won't run...blowing fuse

[Jeepfourfun]

Hi everyone, I've been troubleshooting my furnace for a while now and could use some help....I have a suburban SF30F furnace in my Cougar 293SAB, which is blowing a fuse in my converter panel. As soon as I replace the fuse, it sparks and blows again. Long story short (no pun intended), I have isolated the short to the furnace by cutting the power supply wire at the connection into the furnace itself. Put a new fuse in, and it didn't blow! My question is....now what? I have visually inspected all the wires in the furnace itself, can't find a short or burn mark or loose connection anywhere. Another kink in the wheel....my ac only blows warm (not cool) air when I'm hooked to shore power. Leads me to believe it could possibly be a short in the thermostat wiring? I know they run off separate power supplies, but could a short in that wiring or the thermostat itself effect both the ac and the furnace? I'm almost at my wits end and ready to camp, next step if I can't find anything else is to call a mobile rv tech....thanks in advance for any input!!!!

[scott24]

Take the stat out of the loop. Mark and remove the wires from it and put a new fuse in and see what happens.

[Jeepfourfun]

good idea...if I remove the thermostat from the wall and pull the wires out and it blows the fuse after I reconnect the furnace, I know it's not the issue! Thanks for a simple little tip!

[scott24]

How's the trouble shooting going?

[Jeepfourfun]

Thanks so much for your interest! Unfortunately I've been super busy at work the last 2 days, plus a 2 week old baby at home. That being said, haven't had time to get to the camper in a couple days. Might have a mobile rv repair guy come out soon, as we've got a trip planned 4th of July weekend and my schedule doesn't lighten up before then. If I go that route, I will DEFINITLY come back here and post findings/remedies. Thanks again!

[Jeepfourfun]

Well.....after scheduling a mobile repair tech to come out 2 weeks ago....he no-showed on Sunday, even after I called and confirmed Sunday morning. No phone call, no message, nothing. And shocker, he won't return my phone calls. So after calling 8 more dealerships, mobile techs, etc I found someone to come out. Took him all of 5 minutes to tell me my AC was out of coolant and needs replaced, and then he found a short in my furnace. The short is now fixed and the AC is being shipped in and installed Monday. Just thought I'd give an update!

[jje1960]

Over Memorial Day, we went to use our furnace (which worked in March while dewinterizing) on the way to Upstate New York. Woke up in the morning.... No heat. Played around with fuses (none blown).. Lot's of normal clicking... No blower. Long story short, when we arrived at destination, I started to get a bit more aggressive and found the mud dauber line with a flashlight into the furnace exhaust vent! Much cussing later... Tried a long shot, took a two foot long tie wrap, poked into the exhaust vent while activating the thermostat... The blower started and spit out the dried mud pieces! We used a shop vac and sucked out the rest, the furnace is working fine now. Very lucky indeed. I purchased and installed a screen over the exhaust vent (which I should have done years ago) and all is well. Depending on how bad the blockage is, this may or may not work for others before replacing the entire furnace, of course this is if same problem as ours exists. Hope this helps someone.... GET A SCREEN FOR THE EXHAUST!