Heat pump/air handler issues

[lombard]

Need a little help troubleshooting an issue I'm having with my air handler. Living in FL, I've got a heat pump system. Works great when cooling, but I've noticed recently that my air handler blower doesn't seem to turn on when in heating mode. I can hear my compressor/condenser unit running, and I can hear something along the lines of light air flow (or perhaps refridgerant?) inside the air handler, but the blower's definitely not running.

Last summer I replaced the existing thermostat (original installation from 2007) with a fully programmable one. Thinking perhaps I miswired it, I just went through the cycle of reinstalling the old one, with the same issue. I've done a little searching on the internet for some troubleshooting tips, but haven't really come up with anything that seems to apply to this particular situation.

Any ideas?

[Uncle Cracker]

If your blower works properly in cooling mode, then you can rule out any motor/capacitor problem. Your air-handler may have a relay board in it which reacts to the various inputs to activate your blower in heat or cool mode, and also will trigger the auxiliary heating elements if needed in heating mode. I suspect this control board is where your problem will be found. If you can get your hands on one without buying it, you can easily make the swap and test it.

[lombard]

Thanks for the advice. I opened up the air handler and have done a bit more troubleshooting. The sound I was hearing from it turned out to be the blower motor. Looks like it is alternating between trying to turn one direction, then the other. Makes me think its transformer blew (though I haven't heard of that happening before). I double checked and it appears that the same thing is now happening when it tries to cool.

[Uncle Cracker]

Then it may be in fact a motor issue, although a control board is still a possibility. Your blower motor does not, I think, have a "transformer", but may very well have a starting capacitor, which gives it a little extra "oomph" to get it moving. A bad capacitor might make your motor act the way you describe, so I would now look at that first. It's cheap enough to replace, as long as you get one with the same ratings as the original, and hook it up the same way. Remember before you do any electrical work in that thing the you have to turn off all the breakers, and that there will be at least two sets, one for the outdoor unit, and another for the air-handler.

[RAFlorida]

+1 with Uncle Cracker, but

becareful of the capacitor; it may have a charge on it if it's still good. IOWs short the cap between terminals w/a screwdriver.

[lombard]

Well, I've about come to the end of my troubleshooting abilities. I verified the transformer works, and the control board seems to work. Next guess is the start capacitor. Problem is, I think it must be self contained with the start relay(s), because I'm not seeing any standalone capacitors. Ugh. Hate to spend $100 ordering a new capacitor just to find it doesn't fix my problem.

I tried to manually "kick start" the blower motor when it was trying to spin, but it didn't seem to help. Man, I hate calling service personnel for stuff like this that should be simple.

[RAFlorida]

Some time the cap will be mounted

on the fan housing, other times where the wire feed come into the houseing of the indoor unit. Should be anyway. Is there by chance a terminal compartment for the wiring where it may be hiding?

[chopnhack]

When you said that it is trying to turn one way and then the other, is it partially turning and then the fan blades/squirrel cage falling back the other direction? Kinda like a pendulum, with the sound be heard as its going in one direction, but not in the other? If that is the case, maybe the relay that controls the secondary winding is opening prematurely before the motor can kick over or the cap is bad as uncle C said already? Just a thought... Good luck and let us know.

[master53yoda]

1.how many wires are coming out of the motor.
2. what color are the wires. typical fan motors are 3 or 4 speed PSC (Permanent split capacitor) motors. They do not use start capacitors or start relays.
3.to eliminate the thermostat wiring , remove the thermostat from the subase and jumper the red and green terminal at the air handler. that should start the fan. If it does and the fan runs, remove the jumper at the air-handler and jumper the r and g terminals at the t-stat. If the fan runs when the terminals are jumpered at the furnace but not at the stat the wire between is the problem. remake all connections and try again.
If the fanruns when jumpered at the stat the stat is bad.

some of the newest high efficiency HVAC equipment have variable speed motors. If this is the type motor you have it is out of your ability do anything with it because of the internal electronics invovled.

good Luck

[phi1l]

many motors of that size have a starter coil that is supposed to spin the motor up to a minimum speed & then a switch is supposed to turn on the power to the main motor, it sound like there may be something keeping the motor from spinning up fast enought kick in the main power switch. If the motor just spun at a low speed, that would indicate circuitry in the motor it self.

[lombard]

Thanks for all the suggestions guys. Turned out to be an issue with the controller housed inside the motor casing. Got a new blower motor installed today, everything's good. Luckily, the parts were covered under warranty, so I only got stuck paying for labor and part shipping ($295). Still hurt to cut that check, but at least I have heat now.

I feel a little less stupid now too. The technician couldn't find an external start capacitor either...