The other day while working at my computer, I began sweating it big time. Oh, the work was easy, but the room grew hotter and hotter. And like the classic frog in a pot, I didn’t notice until I was hot under the collar (and everywhere else). Argh… not again! It wasn’t too long ago that I repaired this same AC. That time, it was blowing hot air: the #1 most common HVAC failure. This time it’s blowing no air at all: the #2 most common failure. And without circulation it can’t do much conditioning to the air. Thanks to my misfortune, we’re going to show you how to easily fix your own AC. Once again.
Second Time’s A Charm – How to Fix Your Own AC When It’s Not Blowing Any Air
The expression is “third time’s a charm”, but I really don’t want a third time. The next failure might be a simple, inexpensive thermostat replacement. Or it could also be a costly compressor issue. And believe me: ain’t nobody got time for that! So far, I’ve had the “good” HVAC problems. (Though this one will cost me a little more than last time.)
* If your HVAC is set to “cool” but is blowing hot air, check out our previous AC repair article.
* If your HVAC is running but NO air is blowing through the vents, check the filter. If it’s clogged, replace it. You should be replacing the filter on a regular schedule. If there is still no (or very little) air movement, continue reading.
* If your HVAC is set to heat but cold air is blowing through the vents, it’s probably a heater coil, relay or thermostat issue. More on that later.
Safety Is #1 Priority! – Kill The Power, Not Yourself
Before proceeding, be aware that working around electricity is inherently dangerous and can have lethal consequences. At Home Fixated, we’re all about getting our DIY on. But we’re also about working safely. A job like this is only for those who are comfortable and informed enough to handle the task with confidence. If that’s not you, consider calling in a professional. There’s no shame in a wise decision.
NEVER work on live circuitry and ALWAYS keep your wits about you when poking around any electrical wiring. Check – then double check – your work before restoring power. Now let’s quench this sweat shop!
Blower No Bueno – When There Is No Air Coming Out Of The Vents
If no air is circulating through the ducts, the blower fan (aka “furnace blower”) isn’t huffing and puffing as it should. First, go to the heat pump and see if the condenser fan (the exposed fan under the grate on top) is working. If it isn’t running either, check the breaker. Or you may have a thermostat issue. If it is running (and the AC filter is clean) you likely have a problem with the blower fan.
President (And Only Paying Member) Of My Own Fan Club
I swear I’ve dealt with more fan problems in the past year than any entire decade of my life: seven, to be exact (including the home HVAC)! It’s time to disband this lousy fan club of mine; I’m the only sucker paying dues. Side rant over.
The blower is located in the air handler. And the air handler is usually located in the attic, garage, basement, a dedicated closet, or – if your HVAC is a one-piece package (like mine) – in the outside unit itself. Oh, and the head bone’s connected to the neck bone.
Check For Fan Rotation – It Really Blows When The Blower Doesn’t Blow
Manually spin the blower wheel. But, again, make sure circuit breakers have been switched off first. You definitely don’t want it to kick on with your digits anywhere near the twirly bits! If it feels stiff, the bearings are probably shot (or something is caught up in the blower wheel) and you’ll need to replace the motor.
Restore power and turn the unit on to see if the blower activates. It turns out mine actually was spinning, but way too slowly to do anything of value. If it appeared to be running full sprint, however, I’d look for a leak or detached section of ductwork. Or maybe the squirrel got loose and gnawed a big hole somewhere along the line.
If your squirrel cage blower never tries to start up at all, check with a volt meter. But seeing signs of life, I know it’s getting power (some power, at least. It never hurts to verify).
If Your Blower Motor Uses A Run Capacitor, Start There (That’s Probably What’s Wrong)
My HVAC has a multi-speed blower motor (though it only uses one speed) containing an internal “ECM” (Electronic Control Module). This motor does not use a run capacitor. Single speed motors, on the other hand, often do use a run capacitor (and usually don’t have an ECM).
For blower motors that use a run capacitor, odds are the capacitor is your problem. Assuming the motor shaft spins freely, start by testing and/or replacing the capacitor with a new one of the same voltage and capacitance value. If you replace the motor, still install a new capacitor. Our last DIY AC repair article has some tips for testing and replacing a motor run capacitor (be sure to discharge it first!).
Pull The Blower – How To Fix Your Own HVAC
If you determine the blower to be at fault, it’s time to remove it from the air handler. Switch the breakers off again and then unplug the wiring harness(es).
Disassembly – How To Replace An HVAC Blower Motor
Start by removing the heater assembly. On a side note, if the heater ever stops working, you now know where to find the elements. The heater coils can be tested with an ohmmeter or continuity tester (low resistance is good). If they are good, but not heating, trace the wires and you’ll find the activation relay(s). Sometimes a relay goes bad. The relay(s) is triggered by low voltage from the thermostat.
Position the blower with the motor on top. Then unbolt the motor brackets and pull them free from the chassis. Be careful not to tear the rubber dampers or they’ll have to be replaced. If they aren’t pulling free, pinch and push the rubber through the holes as you pull on the brackets.
Blower Motor – Rebuild Or Replace
In most cases, a bad motor has to be replaced. That’s what I did. But it’s worth noting that some motors – like mine – actually have a replaceable control module (ECM). And in most cases it will do the trick. But I didn’t want to gamble the money, or have to wait for a replacement to arrive.
My local parts dealer had an exact replacement motor in stock and I was good to go. I probably could have found it cheaper online. But leaving there with the part in hand was, for us, well worth their asking price. One night surrounded by pedestal fans was enough. And I still saved a lot of money by doing the job myself.
Don’t Be An Animal – Clean That Squirrel Cage!
Dust build-up on the fins negatively affect their efficiency. So, since you’re already in up to your squirrel nut zippers, go ahead and give the blower wheel a good cleaning (a job best done outdoors).
Reassembly – Get That HVAC Working Again! (Putting The Wind Back In Your Sails)
Assuming your new motor matches the old one, assembly is a matter of reversing the removal process. If it’s different, you may have to re-map the old wiring to the corresponding terminals on the new motor.
Once you get the blower back together, re-attach the heater assembly.
Where The Wind Blows – A Word About Auto Direction Sensing
Most HVAC blower motors are hard-wired to spin either counter clock-wise (CCW) or clock-wise (CW); plug and go. But some (like mine, of course) run an automatic sensing procedure – the very first time it’s used – to determine the proper direction of rotation. According to my local dealer’s HVAC expert, motors like this rely on back pressure to work their magic. So the air handler cover must be reinstalled BEFORE powering the unit on.
The first time the motor is powered, it will spin for several seconds in each direction (repeating the cycle up to four times) to determine the proper operating direction. After doing its thing, the ECM locks out that feature and the motor will always start up in the correct direction. From then on, it’s safe to run the blower without the cover in place.
If the motor can’t figure out which way it should spin, it will default to CCW rotation. The installation guide doesn’t mention that you should first run it with the cover in place, but it does explain how to alter the rotation sensing decision if you need to. Honestly, it looks like a tedious process that I would not want to have to deal with.
Bask In The Brisk Breeze Of Victory!
Finally, I switched the breakers on, turned the thermostat to “cool” and the fan to “on”, then gave the blower the time it needed to run its routine. Within a minute or two cool air was blowing from the vents. And seconds after that hot air was blowing from me as I gloated over saving money with another successful DIY HVAC repair!
Whatever time of year it is, whether you’re running heat or AC, an HVAC is useless without a working blower. And now, if your vents ever stop serving up that sweet nectar of conditioned air, you’ll know what to do about it. How cool is that?