1988 Excella Furnace

[SteveandSam]

I have an NT35 furnace that quit working all of the sudden. Blower works continuously, but no heat. Sounds like pilot light issue, but I thought the blower was supposed to stop working if the furnace didn't light off. Any ideas? Thanks.

[nickcrowhurst]

These symptoms often indicate a new control board is required. Dinosaur makes excellent ones as a direct replacement with several extra useful features, including an internal fuse.
Nick.

[Mr & Mrs S]

Originally Posted by SteveandSam

I have an NT35 furnace that quit working all of the sudden. Blower works continuously, but no heat. Sounds like pilot light issue, but I thought the blower was supposed to stop working if the furnace didn't light off. Any ideas? Thanks.

Mine done the same thing a few weeks ago after traveling a bumpy road in New Mexico. From the outside of your trailer open the furnace hatch, look to your lower left and you should see a control board. Mine was simply held in place by a wing nut on the top front. Take the control board out and clean the plug contacts on the board and the plug. If you have a spray can of electrical cleaner that's even better. Plug it back in after cleaning and try again. Fixed mine!

[acgypsy]

SteveandSam, you need to look at the intake,'bottom' duct to see if any obstruction, i.e. wasp nest. check top one also. turn on furnace and feel how much air is blowing out of top 'exhaust' ducts, hard to tell you how much. there is an interlock called a 'sail switch' which insures enough air for combustion, if not enough air flow, the next two actions will not happen. next on the inside, turn on furnace, after 15 seconds or so do you hear a click, this is the fuel solenoid opening, if no click, sail switch did not close it's connection, if you do hear a click, sail switch has closed and fuel has opened. but no ignition, now the ignitor has not sparked. remove the square panel on the furnace, two screws. what you see in the middle has two wires attached to the ignitor. pull the blade connector off, remove the two screws. top and bottom, be careful of the gasket, THE GASKET SEPERATES COMBUSTION GASES FROM INSIDE HEATED AIR. withdraw ignitor about one inch then rotate 90 degrees to the left, becareful of the electrodes, is black carbon on it , not getting spark, need a gap, small wire brush and scrape off black carbon,, reassemble, with cover off, turn on furnace, look in little window, next to ignitor, to see if there is sparking BEFORE fuel click on. after checking mechanical, then i would check circuit board, best, ac

[SteveandSam]

Thanks to all. This gives me a couple things to look into next weekend.