[leonwr]

This past summer I had the Blower fan replaced on my 1979 York/Borg Warner furnace because of its failure during the summer A/C needs. The blower worked great on Auto all summer. Come winter I switched over to heat and placed the thermostat on Auto and it was not moving air. Placing it on manual setting resulted in the movement of air both hot during the "on" furnace cycle and cool air during the "off" furnace cycle. I ordered a new Blower Furnace Fan limit switch. Honeywell. And installed it. Placing the thermostat to call for heat, I watched the limit switch work and trip the limit switch to call for the blower to turn on. A large spark occurred behind the relay for the blower and the blower shut down. I purchased a new relay and installed it and set up the same scenario. I watched the limit switch work and trip the limit switch to call for the blower to turn on again. This time the main circuit panel tripped. I set up the same again after resetting the circuit panel and this time the limit switch sparked. I decided to let the blower stay on manual for the winter till I can diagnose the problem further and not worry about the cold NJ winter.

Question: Could the Blower wiring from the summer installation of the New Blower work well for summer A/C high speed auto setting but be wired wrong for winter Furnace low speed auto setting??? :vs_worry:

 

[BayouRunner]

You are correct, that most likely is your problem. It wasn't wired correctly. Don't keep trying it or you are going to burn up your new motor. If you are fairly handy and you post a few pictures and a wiring diagram we could help you out. Chances are only one wire is wrong

 

[beenthere]

How many wires are connected to the fan limit switch, 3 or 4?

 

[leonwr]

Seems it will take me a bit to figure out how to get photos off my iphone and on to this site to post the wiring diagram and pictures of the limit switch and connections.

The fan limit switch has 4 wires and I removed the jumper as was needed to match the original limit switch. The previous limit switch has been in at least for the last 12 years that I have been living here. So, the only thing that I believe can be the cause is that two of the wires on the blower instillation need to be switched and that they were only applicable to the blower in heating mode and not in A/C mode.

I am fairly handy but cautious and unfamiliar with HVAC.

 

[leonwr]

additional pertinent photos for information are as follows.