I've got an AC unit in Florida that is only 7 years old. Recently, the air handler coils froze. Called AC tech who replaced the capacitor and all was good. 3 weeks later, they froze again. The motor stopped running on the air handler while the compressor was still running. Tech came out and all he did to test was unplug the cut off switch, place it back and the motor starts running again fixes the issue. About a week later (today), the same thing happened, motor in air handler stops running so coils start to freeze, I unplugged-replugged and everything is good.
Any idea what could be happening? All systems seem to be in line. I've got a wi-fi honeywell thermostat (the cheapest one without any crazy features) and I'm inclined to start thinking that could be the issue? Any way to test/diagnose that besides waiting for this to maybe happen again?

Its not your stat causing the issue. So when you say motor are you meaning the blower fan?

Tech came out and all he did to test was unplug the cut off switch, place it back and the motor starts running again fixes the issue

About a week later (today), the same thing happened, motor in air handler stops running so coils start to freeze, I unplugged-replugged and everything is good.
Could you expound on those statements? What cut off switch are you referring to?


I've got a wi-fi honeywell thermostat (the cheapest one without any crazy features) and I'm inclined to start thinking that could be the issue?
Right now I would tend to disagree.

Assuming that by "cut off switch" you are referring to the safety switch that cuts off power when you remove a cover, I would suspect a faulty switch or a faulty connection to the switch.

Next time a failure occurs, remove the cover and press the switch with out touching anything else. If blower motor starts, that would confirm my suspicion and it is probably a defective switch.

Purchase a voltage sensor. If blower motor does not restart, test for voltage both going to the switch, and leaving switch to motor. Try not to move any wires around. If you have voltage to the switch but not leaving the switch, begin moving wires close to the switch around. If voltage returns you probably have faulty connection to switch.

Let us know what you find.

Its not your stat causing the issue. So when you say motor are you meaning the blower fan?
Yes, I apologize for terminology. I do mean the blower fan.


Could you expound on those statements? What cut off switch are you referring to?


Right now I would tend to disagree.

Assuming that by "cut off switch" you are referring to the safety switch that cuts off power when you remove a cover, I would suspect a faulty switch or a faulty connection to the switch.

Next time a failure occurs, remove the cover and press the switch with out touching anything else. If blower motor starts, that would confirm my suspicion and it is probably a defective switch.

Purchase a voltage sensor. If blower motor does not restart, test for voltage both going to the switch, and leaving switch to motor. Try not to move any wires around. If you have voltage to the switch but not leaving the switch, begin moving wires close to the switch around. If voltage returns you probably have faulty connection to switch.

Let us know what you find.
Very interesting. Thank you so much for an answer. Yes this is the safety switch that cuts off power when you remove it to then remove the cover. I'll have to wait to see if this occurs again then. It seems odd just because when the fan shuts off there are still gurgling noises occurring and just the fan has not turned on.
Is there a way to test this prior to waiting for it to occur again? I know when the tech was here he tested the voltage of the fan and everything checked out well it was not over-working. So the switch may really be it. I just would like to test it before it happens when maybe I'm not home or something and caused even more trouble. Thanks again!

fan shuts off there are still gurgling noises occurring
That sounds like refrigerant equalizing. Is outside unit running when cover is removed?

Only other way to test would be to temporarily wire around switch and see if fan fails again.