I have an old armstrong unit. It start's fine motor and fan. After awhile the fan stops while the unit still runs. Is this normal?

Try changing settings on the controller,

I would start by testing or replacing the blower motor resistor, it's located next to fan, fan wires goto it. When fan stops try tapping on it. The resistor is more common than the fan

on the motor should be a diagram detailing the wires. brown white goes to either side of the capacitor and brown wire to other side of capacitor. hi speed goes to normally open contact on the indoor fan relay and the wire designated common on the motor goes to the other side of power from the relay contacts.

Well, the answer is yes. I have seen a bad capacitor cause a fan motor to run backwards. BUT..... After replacing the capacitor and WIRING it up the right way, everything should be fine. A lot of aftermarket condenser fan motors are reversible, so it can run counter-clockwise (CCW) or clock-wise (CW). However, most factory fan motors come one directional and on your specific unit, the air should always push out of the top. Running the unit with the fan going backwards will actually some-what do it's job, but damage other components like the compressor because it runs at higher operating pressures than what it is designed for.

Have someone else look at it! That's going to be the best advice I can give you. If they can prove that a capacitor caused the motor to permanently run backwards..... I want to know! Hope this helps and good luck with your unit.

Hello, this could be either a bad capacitor or bad fan motor. If the fan starts by giving it a push then replace the capacitor, if it does not start the motor needs to be replaced.

That thing connected to the capacitor is a booster for the compressor .But if the outside fan doesn't work , the compressor will shutt off on overload because the high pressure in the condenser coil.
First try to replace the capacitor in the condensing unit (it's the only one that works for the compressor and the fan motor) ,but if the fan doesn't start, you need to replace the fan motor.

You are likely low on charge and the unit is freezing up. You need some with gauges to check. You should not try to run this unit until then or it will burn out the compressor.

Many outside AC units have just one capacitor that starts the compressor and the fan. Some units however have two. Just follow the wires from the motor to the capacitor, pull it and test it. Make sure you disconnect the power from the unit by pulling the fuse block first. If the capacitor is good the motor may have siezed up or burned out.

I gather that it is the outdoor fan motor that runs a bit then stops.

Fan motors that stop by themselves are overheating and going into self-protect. The fact that you replaced the motor and capacitor opens up a whole world of "which wire is in the wrong place". I could do this if I could see it, but I can't see it. You're probably going to wind up calling a service man to sort out the wiring.

You have done a good job under the circumstances. It could be a bad start/run capacitor as well. It carries a lot of amperage so I suggest hiring a technician to check the capacitor and the motor.