Murphys law....

Sean · December 19, 2004, 04:13:39 PM

Why can't Furnaces ever quit in the Spring or Fall? It waits until its 17 degrees outside, then quits...

I pulled the access panels off and found that the blower fan would barely turn. went back upstairs and proceeded to spend an hour online trying to figure out which motor I needed. Finally decided to just pull the Motor. Shouldn't be but two or three wires right?...

After seeing that the control system for the furnace was all tied into the wiring for the fan and looked like something that should be inside my computer, I decided to pull the fan without unwiring it and see if I could take it apart.

I pulled the ends off the motor, cleaned a bunch of Crud and Lint out of the bearings, re-oiled them, re-installed everything, and amazingly it works fine now. I must have just used up my good luck for this Month...

Crosley.In.AZ · December 19, 2004, 04:30:34 PM

it amazing what is inside the boxes.

The new 5 ton heat pump I installed on my shop has circuitry inside so the motors "ramp up" to speed. They do not simply come on in a burst to operating RPM.

And I will add ..... some of the local HVAC folks i've delt with in the past year do not look like they could tell the diffference from a door knob to a door bell or a/c parts.

Sean · December 19, 2004, 04:49:34 PM

Quote from: "Crosley"The new 5 ton heat pump I installed on my shop has circuitry inside so the motors "ramp up" to speed.

I don't know if mine Ramps up, but from what I found on the motor, its got 4 speeds. Low, med-lo, med-hi, and High. I guess thats why it has to have all those "Brains" in that box...

purplepickup · December 19, 2004, 05:37:09 PM

Sean, I think you said recently that your boss is putting you in charge of an HVAC crew and you didn't know anything about it. It sounds like you know more than you thought you did

SKR8PN · December 19, 2004, 05:55:48 PM

George........in the military,they called that "OJT"

Brootal · December 19, 2004, 06:27:54 PM

Quote from: "Sean"
I pulled the ends off the motor, cleaned a bunch of Crud and Lint out of the bearings, re-oiled them, re-installed everything, and amazingly it works fine now...

Well maybe you shouldn't use it as a clothes dryer!

Good to see Hot Rod Ingenuity comes in handy around the house too.

enjenjo · December 19, 2004, 06:54:22 PM

Seems like everything has a processor in it anymore. Heck, even irons have a chip in them now days.

Sean · December 19, 2004, 07:10:57 PM

Quote from: "purplepickup"Sean, I think you said recently that your boss is putting you in charge of an HVAC crew and you didn't know anything about it. It sounds like you know more than you thought you did

Well, maybe a little bit.

If I'd had to do anything with the wiring I would have had to call somebody though.

Luckily for me, the kind of HVAC work they want me to run will be Commercial, and New Construction. Basically installing the Units and Ducting, then calling our Service Man to do the wiring and charge the system.

phat46 · December 19, 2004, 09:28:51 PM

My first "real" job was as a heating and AC installer. (1973) The difference between those units then and todays is like comparing a '53 Chevy with an '02 Mitsubishi. My daughter has two new units in her house and last winter one of them quit so i had a look at it. All I could tell was that it kept blowing the 5 amp AUTOMOTIVE fuse on a wire that dead ended at the fuse....an obvious short, but how to tell in the maze of wires on the thing. I told her to call the furnace repair guy. :oops:

entodad · December 19, 2004, 11:16:09 PM

Those new fangled ramping up motors are pretty complicated.
I put in a 12SEER CH/A unit in my rent house a few years back.
The blower fan has about 12-15 wires going into it, and a circuit board complete with many transistore, an IC and other odds and ends on it as well. Essentially what it does is create a loop that takes input from the heater/air conditioner area and blows at a rate equal to the amount of heat/cooling available in the unit. Problem is, if you ever have to replace one, the price is about 5-6 times what one of the lower tech on/off rigs are.

It is about a 1/2 HP motor, I spent about $350 wholesale to replace it doing all the work myself. In addition to that when the motor went, it also blew out the control board as well. (another $100). If I had it to do over again I would have put in a 10SEER unit with the lower teck blowers, etc.