Blower Motor Running in Reverse

I noticed today while running the A/C that there wasn't anything coming out of the vents. I went down to check the furnace/AC system. It is a Carrier unit probably original to the house. Install stickers on the HVAC ducting put it at around 1991. The blower motor is mounted inside the furnace part while the A/C unit sits on top of the furnace. The furnace is a Carrier Crusader, natural gas, Product # 58SSC055---101GC, Model # 58SSC055-GC, Series 100, Blower No. 511, Blower Motor HP - 1/3hp. House is a tri-level.

Anyways, I took out the air filter and noticed I wasn't getting any air flow from the blower motor (it was on and sounded fine). I stuck my hand inside the blower motor enclosure on the air filter side and felt little to no air flow. I stuck my hand on the other side of the blower motor and felt air flow (hard to tell how much).

I am assuming that somehow the motor has reversed polarity and begun spinning backwards, but I'm not sure how or why.

The thought occurred to me to reverse the wiring on the motor to get it to spin the other way, but I'm not a big fan of playing around with wiring and I'm not sure if it would work anyway.

Can anyone provide any help or insight? I've got about a day before I start getting an earful from my significant other about how hot the house is (luckily my son is too young to complain yet).

 

My guess is that it is unlikely the motor would switch direction unless you or someone else have done something to the circuit lately.

The filter side is the inlet (intake) to the blower, correct? My experience is that usually it is harder to detect flow with your hand from the intake side. Use a light weight yarn, a thin strip of paper, or a lighted candle would help you proof if there is air flow in that area.

If the fan is running and you are getting no flow out of the flow register, most likely you have substances impeding the flow path. You could use a lighted incense to detect micro air flow at the registers (and, yes, the flow direction too, to proof that you have a revered flow). Try cleaning up you air filter. Check if there are any flow dampers in the passage(s) that got shut unkowningly.

Good luck!

Shay

 

It's usually caused by a bad motor run capacitor. Look for a small metal can mounted on the side of the blower housing. Be sure to turn off the power and use an old screwdriver across the terminals of the cap to discharge it. Look thru some of the recent posts here, there's a lot of info about capacitors. Let us know you make out or if you have any questions. Thanks.

 

Hello Shay,
Thanks for the response. I just realized how big of an idiot I am for my first post. After looking at the duct work and taking off a few panels I realized how the air flow is supposed to work (actually it didn't really occur to me until I was sitting there in from the of the unit with the front panel off of the A/C unit turning the fan on/off and wondering why there was air blowing on my balding head).

I also was able to see inside the enclosure and saw a sticker for proper blower motor rotation and it is/was spinning in the proper direction.

Now I am able to turn the fan on and get air flow which leads me to my next question. I am guessing the evaporator coils were frozen up and restricting air flow (this would explain the puddle of water coming from the A/C unit after I turned it off). I need to do more searching on this, but what are some common causes of this?

 

dirty filter, refrigerant shortage, dirty cooling coil and usually the blower is dirty as well, insulation inside a return duct that came loose and is blocking air flow.

 

I suspect low refrigerant is the culprit. I forgot we had a service tech come out last year when the unit stopped blowing cold. Apparently the refrigerant was low. The guy filled the system back up, but didn't search for the leak (I wasn't happy, but I wasn't there). Looks like it's time to call someone to come in to properly diagnose and repair the system.

Thanks for all of the helpful replies.

 

you're quite welcome

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