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Furnace Problem Fan Related

1K views 4 replies 4 participants last post by  LocalSimpleton 
#1 ·
Hello all,

Here's what I got. Two days ago the house got up to 74 and I tried to turn the air on. The compressor was running but the blower motor never started. By time I realized the house was still warm, the compressor was a block of ice and I shut it off. I was busy and couldn't wait for it to thaw and check for problems. Soooo, its ohio, I tried to turn the heat on last night, plenty of fire, the fan still does not run.

The fan does not start if you set the fan to ON. I opened the furnace and checked the capacitor, tested A OK. I taped the door switch shut and started checking a few voltage points, where I checked was good. I turned the HEAT on and switched the fan to auto. I have fire, I'm testing more points watching the limit switch creep up. Then the limit switch made a tiny bang (like a coil that was bound up released,) then the fan turned ON. I stopped where I was and let the house get up to 70, it was down to 59 by time I got this far. It cycled the fan on and off multiple times to warm the house up, seems like the air temp was a little cooler than it wanted coming in. Fan still does not work when set to ON.

I'm having a mental breakdown I think. I'm assuming at this point the limit switch is bad and needs replaced, but does this have anything to do with the switching the fan to ON? And how does this relate to the blower not running when set to AIR? Could half of the limit switch short out and cause this?

I know you guys want details, but I honestly cant tell you exactly what furnace it is lol. It appears that this furnace is sold as about 40 different manufactures. This is the model on the sticker, PCMU-LD16N095B.

Any help you guys can provide will help me immensely.
 
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