My central A/C air handler stopped working. The fan motor is a 220V single phase, capacitor start. The motor gets hot, the capacitor stays cool. The fan turns freely when pushed by hand, but pushing it does not get the motor running.
It sounds like the start winding is opened but I think you should be able to get it to start by spinning the rotor (with power applied of course) if that were the case. I work on DC and three-phase motors so I’m a bit out of my element with single-phase but there used to be centrifugal switches to disconnect the start winding once the motor is at speed. Those can fail and keep the start winding in too long and burn the winding or the capacitor.
Can you give more info from the nameplate? Manufacturer, etc. It ould be nice to know whether the capacitor stays in the circuit or is disconnected on this one in normal operation. Also there may be a thermal overload that has tripped or failed.
Your A/C “handler”. Do you mean the compressor cooling fan or the blower that moves the air in the house? The compressor cooling fan isn’t usually connected directly to the compressor. If the compressor isn’t turning then I would start with the relay that turns it on.
Notice that top of the capacitor is slightly recessed and absolutely flat. Look at your cap. If it is “swollen” on top or bulging it is a certainty that the cap is bad----and the likely source of the problem.
If it’s bad, don’t try to replace it without getting direction from us.
One last thing. Even if the compressor will run, you may still have a bad cap. On dual caps, sometimes only one side of the cap goes bad-----letting the compressor run but not the fan. It’s low hanging fruit, but it’s really common low hanging fruit: visually inspect the cap.
If neither the fan or compressor run, it is possible that the ‘relay’ is bad. (although in these applications they use a definite purpose contactor)
Both the compressor and fan will route through the **same **contactor. We see bad contactors often enough to keep them on our trucks, but a more common cause is blown fuses (not to be confused with the fuses or breakers in the main electrical panel) or bad capacitors.
If it’s the contactor than wacking it with a piece of wood may bring it back online and that would be a clear indication of what to replace. If nothing else, it will allow some frustration to be vented.
The air handler is the inside unit; i.e., the evaporator. This is the fan that circulates air through the house. It is definitely 220volt, 1 phase. And while I haven’t checked for power, the fact that the motor is getting hot is a pretty good indication that it’s getting it (also, I could hear a hum coming from the motor until I shut the breaker off).
If it is the indoor fan than there are 2 likely causes, in order of likeliness:
1) A bad cap. If the motor is hot (and the wheel will spin freely by hand, indication that it’s not bound up) than it is likely that 220V is being applied. If it is the capacitor on the indoor blower, it will not bulge----but can be bad all the same.
2) A bad motor Sometimes bad things happen to good motors.
The fact that the motor is hot suggests that the windings are not open, and that the cap is the problem.
If you want to try this and avoid a tech visit, replace the cap. The other thing you can try (with the power off, of course) is to switch the motor leads. Take one of the leads not being used and put it where the one that is being used is; IOW, switch fan speeds.
Awesome response, thanks. I will try switching the leads. If not, where do I find a replacement capacitor? I assume it’s not the sort of thing Lowes would carry. Would an electrical supply store have it, or would I have to seek out a place that specializes in motors?