Blower Motor Not Working: Which Kind You Have

Look at the end of the motor

The older kind. A plain motor with a separate capacitor beside it and a handful of coloured wires going to a set of terminals. It runs at fixed speeds, chosen by which wire is connected where. The capacitor is the part that usually fails, and it is cheap.

The newer kind. A longer motor with an electronic module bolted onto the end, often with fins on it and a plug rather than a bundle of wires. It varies its speed continuously, it is much quieter, and it costs a great deal more.

Why it matters for the bill. On the older kind, the run capacitor is a cheap part. On the newer kind, the module can fail without the motor, and on many of them the module can be replaced on its own, which is worth asking about before agreeing to a whole new motor.

If somebody quotes you a motor, ask which of the two you have and whether the module alone would do it. That one question can save the price of a whole motor.

Hum but no spin, and what to do about it

A motor that hums and does not turn is a common picture on this page, and there are only two real answers.

Power off at the breaker. Then reach in and turn the blower wheel by hand.

It spins freely and keeps going. The motor has the will and not the shove, which on the older kind is the capacitor. On the newer kind it points at the module instead.

It is stiff, notchy or it grinds. Bearings. A new capacitor will not help, and a motor in that state is at the end of its life rather than in need of a part. On the newer kind, Genteq says a slight cogging feel is normal.

It spins freely and still does nothing with the power on. Then look further back: the panel switch, the low voltage fuse on the board, the relay, or the board itself: the order to check those in.

Weak, intermittent, or only on some speeds

It runs but the air is weak everywhere. Usually not the motor at all. A blower wheel packed with dust spins at full speed and moves a fraction of the air, and it is very common on any system that has run with a poor filter.

It runs on some speeds and not others. On the older kind that is the speed taps or the board, not the motor. Heating and cooling use different speeds, so a fan that works in summer and not in winter fits this exactly.

It starts, runs a few minutes, then stops and comes back later. The motor is overheating and cutting out on its own internal protection. That is usually restricted airflow rather than a bad motor, and the same restriction trips the limit: what a tripping limit is telling you.

It squeals. On an older belt driven blower that is the belt. On a direct drive one it is a dry bearing, and it gets worse every week.

Never oil a motor with no oil ports. Carrier, Goodman and Lennox say their blower motors come lubricated and need no more, and Carrier says you can tell them by the absence of oil ports on each end.