[A.W.Dille]

I have a Miller A/C electric heating system in my doublewide. On auto worked fine with the A/C all summer. Now that cold weather has hit only way to get the blower to work on heat is to turn it on manually. I found a 10gauge wire that was burnt in two and got some ten gauge stranded (like the original) and made a new wire but still the same result. Gettting frustrated because I'm not sure where to look next and my finances won't allow me to call someone in at the present time. Not sure if the relay has gone bad or if it may be the thermostat on the wall. I'll have to look later on to see if I can find the model number and post it. Looking for possibilities on where to start checking. Thanks in advance. Alan

[4dblnkldude]

Sounds like a thermostat issue to me.

[indymanjoe]

wag here.sounds like the thermostat in the unit isnt energizing the blower.the burnt wire may be in series with the thermostat that turns the blower on.Model # will help.

[A.W.Dille]

Ok the numbers I've found are these. Listed 601S, Model MCEF-15H, MCEF-15AC. Hope this helps.

[necdb3]

Blower motors typically have several separate windings for different speeds. Sounds to me like the windings for the heater speed may be an open circuit. Heaters usually run the blower at a slower speed on heat mode VS. air conditioning mode.

Are there wires that are NOT in use on your blower motor?

[Stuckinda60s]

There should be a fuse between the violet and red wires in the 24V Whatever caused the white wire to burn out should have blown that fuse. Check the transformer for heat, it may have shorted between the 240 and 24 volts. If it looks okay, check the voltage on the grey and violet wires from the transformer. It should be 24V AC.

Here's a link for what should be the schematic: http://www.nordyne.com/Literature/707716c.pdf

By the way, note that any wiring needs to be replaced with 105 deg C thermoplastic wire of the same gauge.

[A.W.Dille]

Last night when I was checking the model numbers and rechecking the wiring, had the furnace A/C shutoff on the wall thermostat and hard a relay clicking every few seconds. Only way I could shut it off was to cut off the breaker in the box. Diagram is still legable but dirty and hard to read in places. The wire that was burnt was a black wire and when I replaced it I used THHN stranded 10 gauge. Only thing I could get at the time of night I first started working on it. As soon as I pull it apart again (later today or this evening) I'll be able to post what that wire was connecting and may help in the diagnosis. Thanks everyone for the help.