Monday, March 10, 2014

Air Handler Blower Motor

I had my TXV valve replaced last summer and my AC worked ok after that. I live near Dallas and it struggled to keep my home temp below 78 during the day in the heat of summer. That's a bit beside the point (though if you have tips on improve the performance please let me know).
The problem right now is the air handler inside is not moving air. The outside unit kicks on and runs when my thermostat switches to cool. Also, I can hear the refrigerant being moved and the casing of the air handler near my filter gets cold. I don't think the problem is there. I pulled the breakers to inspect the PC board, relay and capacitor and I don't see any damage to them. There is a red LED that blinks on for 2 seconds and then off for 2seconds when there is power, which I think means the PC board is functioning correctly. I have a multimeter, but would appreciate some instructions on test each of those components for failures.
The one problem that seems to be obvious is the blower motor looks to have some damaged coils. I removed the leads to the motor to see if there was power being supplied to the motor, and my multimeter red about 240 volts with thermostat turned on. Odd thing though, when I turned thermostat off, I still read 240 volts. I had 4 wires hooked up to my motor, yellow from board (I think) to H port (M and L had no connection), brown was soldered on motor and connected to CAP and so was purple. Another purple wire came from board to CAP. Green wire grounded motor to blower casing. The multimeter readings above came when I attached leads to the yellow wire that went to motor and purple wire that went to CAP.
An I right to think I can keep this same configuration and just replace the motor, or am I setting myself up to blow another motor? Sorry for the length...

Welcome to the forums.
In order to read the voltage to the motor you connect your leads to yellow and purple. You did and measured 240vac. That's what you should see.
To see if the voltage is not there when the thermostat is off you will need to pull the purple INSULATED terminal wire off the capacitor. Be careful......that cap will hold a charge which is what you are seeing now when you turn off the thermostat. Check from yellow to that insulated terminal on the purple wire. You should no longer read 240 vac.
Since you measured 240vac on the motor and it wasn't's bad. Sometimes just the cap goes bad but usually the motor will hum or try to spin if you help it. If you replace the motor...replace the cap with a new one also.

Thanks for the quick reply PJmax.
I pulled the motor and disconnected the leads before I measured the VAC. I basically has the yellow insulated wire and the purple insulated wire hanging down connected to my multimeter as I cycled the thermostat on and off. I read 240VAC no matter if the thermostat was set to COOL or OFF.
Did I test it incorrectly? What does it mean if I always get the 240VAC reading?

You shouldn't get the same reading. Make sure the thermostat is set for automatic mode..... not fan on.

Two questions:
1. When I went back to double check my multimeter readings, I confirmed that I get 240vac even when my thermostat is off. Does this indicate a failure somewhere else (relay, CB board, etc)? How can I check those components for failure? I have attached pics of the multimeter reading and the leads connections. I also have pics showing my thermostat on and off, but I couldn't get them to upload. I can send them via email if that helps.
2. Do you know of a reputable place where I can purchase a replacement motor and capacitor? I searched and called many places in McKinney TX but I'm having difficulty finding a dealer that will sell me replacement parts because I'm not a licensed HVAC tech and I don't work for a repair company. Emerson model K55HXLYW-0310. 3/4hp, 208-230vac, 60Hz, 3.8A, PH 1, 1075rpm/3 speed, frame 48Y. Capacitor is 15MFD, 370vac. A local repair guy told me to take my motor to a certain supplier and pop it on the counter and they would get me a replacement. However, I had already spoken to this supplier on the phone and they said they would not sell to me. The repair guy was surprised, so he offered to sell me the motor and capacitor from his stock. He said a generic 3/4hp, 1075rpm RESCUE motor would work fine. Is that true?

I'm not quite sure what the issue is with the 240 vac present with fan off.
Leave your make and model of the air handler and I'll see if I can find some info.
As far as the fan....the motor isn't terribly critical. That rescue unit should be ok. Rescue/emerson/US motor. Looks like a big conglomerate. I can find the fan online for you. I can't help you much in TX.
We have parts places that sell to anyone. Cash is cash. Parts that is....stuff like freon is restricted.

As long as all spec. on motor don't see why they wouldn't sell you one.All they could say is no.Just say it's for home use.

That's what I assumed about the parts. i wonder what they would say if I showed up at the front desk with my old motor and cap.
I took some pictures of the air handler info sticker. I think it's a York.

I replaced the motor and capacitor with OEM from a York dealer. I installed them both and they work fine. However, the fan keeps blowing after I turn off the thermostat. There is something more than a blown motor going on here. It never shuts off. It just keeps running...

Have you done anything to the thermostat ?
So far, I haven't been able to find a schematic for your unit.
You could try one thing.... look for the green wire coming from the thermostat to the control board. Disconnect it and see if the fan still runs.

I disconnected the green wire and the fan still runs. I took a pic of my thermostat connections. I'm concerned that my old blower motor fried because of whatever is keeping the fan running nonstop. I just paid 225 for a new motor and I sure don't want to replace it again...

You disconnected the green wire at the air handler......not the thermostat. Correct ?
Your unit uses a fan control board that I'm not totally familiar with. I'm trying to find out if the blower is controlled 100% by it. At the present time it looks like that board may have an issue keeping the fan powered up.
A part number off the control board may help.

No, I disconnected the green wire at the thermostat. I'll try the green wire at the air handler when I get home tonight. I'll also take some pics of the control board.

I disconnected the green wire that goes from the thermostat to the control board and the motor keeps running. I'm not sure of the part number, I couldn't see anything obvious. I attached some pics.

Tags: handler, blower, motor, green wire, control board, disconnected green, disconnected green wire, motor capacitor, purple wire, they would, when thermostat, wire that