I'm looking for info and assistance...

The house I bought last year has an old 80MGF2-75R-2 furnace. When bought the house we added air conditioning. When the installer went to hook the A/C to the furnace he had to replace the mother board to an EGC-1.

He commented that he thought that the furnace may be currently operating with the wrong blower motor. He said that it currently has a single speed motor but should have a multi-speed motor (i don't recall how many he said).

Can someone tell me if the 80MGF is supposed to have a multi-speed blower and if so, what would the correct specs be?

The furnace seemed to be working fine with the motor that it has so I didn't worry about it until yesterday when I installed a humidifier on the furnace.

I thought that I would like to run the blower in the "on" setting rather than the auto setting so that it is moving the humidified air all the time. When I put the thermostat switch to "on" it did not turn on. I verified that there is a click when the switch is moved but nothing else.

Is there something that I can do to get the blower to be on all the time? Or is this problem possibly related to not having the proper blower motor?

Thanks in advance for your help.

 

Update:

I took a look behind the control board to see if I could see the motor. I could not (with out more disassembly) get a look at the motor but I was able to see that the Black wire that is connected to the control board on the ACB low pin is not connected to anything in the rear.

This leads me to believe that I do have the wrong motor.

Any insight?

 

All I can tell you is that Lennox requires specialized parts sold only by them. Sounds like the old motor went out and the guy that replaced it to get it up and running and should have ordered the oem replacement and came back to make it right. When the guy that replaced the board, it was obvious to him that he had no other leads to hook up.

 

Since your furnace was originally set up for heat only, it may have been sold with a single speed blower. With air, you usually want a two or three speed blower motor. This pushes out the colder air better when A/C is called for.

The thermostat wiring and connections on the controller board are what allows the blower to run in manual mode. You may need to look and see that the wiring is in place at both ends.

 

Thanks for the replies...

Can someone provide details on what replacement motor I should be looking for?

 

According to the service manual your unit should have at least a 4 speed motor in it.

Lennox 21L91 -- BLOWER MOTOR

 

Even with a discount, that's a bit pricey. But I've found Lennox is to what John Deere is when it comes to parts. You pay for the green paint. An adapter cradle and cheaper motor could be installed, but I wouldn't know which one to recommend from afar.

 

I left that distributor as an example. Using that part number it's available for less.

 

I've been using that part number...but only seem to find lennox parts for around the same price. I've found similarly spec'd motors but with mount mounting "cradle".

Is there a universal one that attaches to these motors?

Thanks again...

 

So...after doing some searching...do these look right?

Amazon Blower motor

or

Ebay Blower motor

And when installed properly, will this fix the fact that the blower does not work when in the "ON" position (unless there thermostat is calling for heat)

Thanks again...

 

OK...I went in to look at the motor. I think that i actually have the correct motor. I found a K55HXBAZ-5899. Which seems to match the specs of the suggested motor.

I think my problem was that one of the wire was pulled out of the harness. Now I'm looking for confirmation of the correct position of the black wire.

The harness had room for 5 or 6 wires but there were only three plus one that was pulled out. The top wire was the white wire, then a blank, then the yellow wire, and another blank, then the red wire. Can someone tell me which spot on the harness the black wis should go?

On the circuit board, its on the ACB Low. and I want it to run the blower at its slowest speed to circulate air for my humidifier. Should the black wire be closest to the white wire or farther away?

With this bit of info, I should be good to go.

 

Your wire is pulled out of a plug. A harness is a group of wires.
A picture would sure help as I can't figure out where your wire is pulled out of.

http://www.doityourself.com/forum/el...-pictures.html

 

Ok...here is the plug from the motor...

The white wire is the top then a blank, then yellow and a blank then the red and there is a spot covered up by the black wire.

Thanks for your help.

 

That black connector looks a little too big to fit in that connector body.
(btw..... black is the highest fan speed)

The service manual only shows wire colors.... not what the plug looks like.

Does that plug go directly into the motor ?

 

The picture is bad...the end does fit into the plug, if the other end is on the ACB Low on the board, where should the other end go in the plug? I'd like it so that the fan runs at a low speed to just circulate for the humidifier.