Furnace blower/air condition stopped working?

Question

My central air condition stopped working all of sudden, on the last day of recent heat wave. The outside unit works fine. I managed to determined that the blower of the furnace is not starting. When I turned the fan switch from “auto” to “on”, I could hear buzz from the motor but no air blow. I tried to give the blower fan a spin and it worked! The blower could work continuously for more than one and half hour (I manually stopped it). Right now this initial spin is absolutely necessary for the blower to start.

Any one could give me a clue what is wrong? This is a York unit, about 10 years old.

Answer 1

It is either the capacitor or the start windings on the motor. Since a capacitor is about $5 and a motor is $100 I would try the capacitor first. Be careful, capacitors hold voltage so even if the electricity is turned off you could still get shocked by touchung the leads. You discharge a capacitor by using a screwdriver to touch both leads. If it is holding voltage you will see small spark. Once you do that, it's ok to touch them.

Answer 2

Sure... your blower fan needs replacing or the start capacitor needs replacing.

Replace the start capacitor first. Replace it with the EXACT same farad and voltage rating as the one that is there now. A start cap is only about $5 and is easy to replace.

If that doesn;t do it, there are several other things it could be but usually will just be an old motor with a bad bearing.

The start capacitor allows a phase shift that gives your fan a kick start. Once it starts spinning, a centrifugal switch takes the capacitor out of the circuit. IT probably is a bad start cap.


Good luck.

Answer 3

You have a lot of suggestions about a start capacitor. It could be that but I doubt it. Being 10 yrs. old it most likely is the start winding of the motor. It does not pay to have this rewound anymore with labor costing more than a new motor.

If the motor does not have a cylinder shape metal case on the top outside of the motor, it doesn't have or use a start capacitor. (cylinder is about 2" round and about 6" long.
Most likely you will end up replacing the motor because of repair cost approaching the cost of a new one. Some heating / cooling shops sell used motors very reasonable.

Answer 4

Sounds like the motor is going bad and will eventually just buzz and not turn at all. There is also a run capacitor attatched to the blower assembly with two brown wires going to it. Sometimes these go bad. Have the capacitor checked first before condemning the motor. Capacitors are much cheaper!

Answer 5

You definitely need a capacitor. The guy that says its the motor is WRONG. I just went thru this,if it runs after spinning it by hand the motor is fine. Its either the run or the start capacitor. Power down entire unit, find the capacitor, try to locate the burn mark or hot spot on it to verify that it is in deed the problem

Answer 6

Yep, no doubt about it, the motor is bad. It is probably either a partially siezed bearing or windings that are going bad rapidly. Either way, the best aproach is going to be to replace the blower. Unless you are an electric motor tech and want to try repacking the bearings.

Home Depot or Lowes will be able to order a compatable blower for you.

Answer 7

The most likely thing would be the start capacitor. If the motor runs at top speed after your initial spin.

Answer 8

There should be a switch in the closet for the fan or if electric heat a disconnect switch. Maybe she turned that off to clean and forgot to turn back on. Also see if a door to the furnace is not closed properly as some have a door switch and the unit will not work if door is not closed right.

Answer 9

Most fan motors have a capacitor on them to get the motor running. I would try replacing that first.

Answer 10

my blower motor on furnace started making making humming noise , but motor not locked up ,you can turn fan blade easy, is start cap bad