To avoid these ads, REGISTER NOW!

Air handler humming, fan isn't spinning

M

mike93lx

ALLIANCE MEMBER
Joined
Dec 9, 2013
Messages
37,501
Location
Richmond, VA
I noticed the condenser for my 3rd floor system was icing up and found the coil covered in ice and the circulator fan wasn't running.

I opened up the AHU and gave the fan a push hoping it would start spinning but nothing changed.

Could it be the cap or is the fan motor likely toast? The cap is not bulging at all

Its a circa 2003 York 2 ton R22 a/c with a 50ishk btu nat gas furnace. I can't see a nameplate on the furnace at all, unfortunately
 
Last edited:
To avoid these ads, REGISTER NOW!
OP
M

mike93lx

ALLIANCE MEMBER
Joined
Dec 9, 2013
Messages
37,501
Location
Richmond, VA
I ordered a cap since it's easy to swap and only $10. If that doesn't do it, I'll pull the fan

Its going to be 100 tomorrow and mid 90's all weekend. Yay
 
OP
M

mike93lx

ALLIANCE MEMBER
Joined
Dec 9, 2013
Messages
37,501
Location
Richmond, VA
The Cobbler said:
I'd be lost without AC , everyday I come home with my fingers crossed that the house is cool
Click to expand...
Same here but I work from home, so it's quite important. Thankfully, this is for the mostly unused 3rd floor, so it won't matter too much for now. I'm going to throw a window unit in to control the temp a bit until I can get this sorted
 
OP
M

mike93lx

ALLIANCE MEMBER
Joined
Dec 9, 2013
Messages
37,501
Location
Richmond, VA
TobeyA said:
After having a few fail on me, I have spare caps for everything, including the pool pump. All labeled with what unit they are for. Now, none of them will ever fail... :)
Click to expand...
I have spare caps for the condensors, but this is the first time I have had a problem with the air handler.

Obviously it only failed because I am unprepared.
 
To avoid these ads, REGISTER NOW!
R

rlitman

Well-known member
Joined
Oct 18, 2010
Messages
24,596
Location
Long Island
mike93lx said:
...Could it be the cap or is the fan motor likely toast? The cap is not bulging at all...
Click to expand...
The only part on an AC cap that would bulge would be the flat end that the terminals pass through. It is supposed to dome out just enough to rip the terminal connections from the pack underneath. But the change can be very subtle.

I would disconnect the power and try to turn the fan by hand. It should be pretty obvious if the bearings are seized up. Burning out a winding is most common in a 3-phase motor when the phase is lost, but also when the cap has been dead for a long time, or from running too much in a brownout. There are other ways to lose windings, but it's not a common failure on its own.
 
OP
M

mike93lx

ALLIANCE MEMBER
Joined
Dec 9, 2013
Messages
37,501
Location
Richmond, VA
rlitman said:
The only part on an AC cap that would bulge would be the flat end that the terminals pass through. It is supposed to dome out just enough to rip the terminal connections from the pack underneath. But the change can be very subtle.

I would disconnect the power and try to turn the fan by hand. It should be pretty obvious if the bearings are seized up. Burning out a winding is most common in a 3-phase motor when the phase is lost, but also when the cap has been dead for a long time, or from running too much in a brownout. There are other ways to lose windings, but it's not a common failure on its own.
Click to expand...
The fan spins freely. No noticeable resistance.

I was thinking of the cap as just for starting, so that's why I tried to give it a spin when it was energized, but I guess it's a run cap.

If the cap doesn't do it, I'll pull the fan.
 
B

brewchief

Well-known member
Joined
Sep 20, 2008
Messages
2,370
Location
Michigan
Do you have power to the fan? Occasionally the relay on the furnaces control board will fail and every thing else works but no blower.
 
B

brewchief

Well-known member
Joined
Sep 20, 2008
Messages
2,370
Location
Michigan
mike93lx said:
I didn't check with a meter but it's humming when the thermostat is calling for the fan
Click to expand...
Good chance it's just the cap then, what size cap?
If it's a 5mfd and one of your spares for the condenser has a dual cap that has a 5mfd on the fan side then you do indeed have a spare on hand.
 
R

rlitman

Well-known member
Joined
Oct 18, 2010
Messages
24,596
Location
Long Island
mike93lx said:
It was the cap. We are back in business.

The old one wasn't bulging, but there was oil on the back of it.
Click to expand...
Well done. Yeah, pressure can blow out the seal. It's not supposed to, but it's a way I've seen them fail.

Make sure the quick disconnect crimps that press onto the cap terminals are TIGHT. If they're not, that leads to heating and premature cap failure.
 
OP
M

mike93lx

ALLIANCE MEMBER
Joined
Dec 9, 2013
Messages
37,501
Location
Richmond, VA
rlitman said:
Well done. Yeah, pressure can blow out the seal. It's not supposed to, but it's a way I've seen them fail.

Make sure the quick disconnect crimps that press onto the cap terminals are TIGHT. If they're not, that leads to heating and premature cap failure.
Click to expand...
Thanks. They were tight both in removing and reinstalling

I'm placing an order for the rest of the caps in my house, as well as my folks.
 
R

rlitman

Well-known member
Joined
Oct 18, 2010
Messages
24,596
Location
Long Island
mike93lx said:
I'm placing an order for the rest of the caps in my house, as well as my folks.
Click to expand...
Good move. If they're over 10 years old or looking rusty, just replace. I don't stock caps though. The shelf isn't good for them.
While you're there, replacing the contactor is usually recommended. I keep a few extras around, because contactors store just fine.
 
You must log in or register to reply here.
To avoid these ads, REGISTER NOW!
Top Bottom