Fan not running

[TTyMiller]

My fan cuts off and winter is approaching. I can tap around on the fan and it will start up and run for a few sconds and then cut off. Any help from anyone.

thanks

[3elements]

Sounds like a loose connection. Have you checked the wiring and grounds?

[BillWilliams]

Do you have an electric cooling fan? Or are you talking about the fan on the heater?

If it is the heater fan you are referencing, the heater fan has three fairly delicate connections and a ground on the outside of the heater box and also on the inside of the heater box.

With a good light beam and some dexterity, under dash panels off, you can see the connections on the box. Take a shot at wiggling those to see if you can pinpoint the loose connection.

If not, take a look at your switch, if not those two, get ready to take your heater box out and do a rebuild. It is a nice winter project.

[germaneighter]

Maybe it's a sticky bushing or worn out brushes.

I have taken apart two heater boxes this weekend. Both blower fans were not running and very hard to rotate by hand. Both had frozen, or very sticky, bushings on the electric motors. I used a small amount of Marvel Mystery Oil on the bushing and one of them now runs great with no noise. The other one is moving but is still very slow. Interesting note: (to me anyway....) even when the fan would not budge it was not blowing the fuse when turned on.

You can lubricate the top bushing with the unit installed if you are a little careful. I believe the bottom bushing requires taking the box out.

Also please note: one box had a three speed blower (1971) and the other was a two speed blower (1972). You can tell by the number of leads on the front of the resister plate, as shown in the previous post. That one is a three speed unit. (4 wires = 3 speed) (3 wires = 2 speed) Both motors were nearly identical. The number of speeds is determined by the resister plate.

If the brushes are worn close to their limit the fan will run intermittently. This will require removing the box then removing the motor via the four spring clips that hold it onto the fan housing.

dave in Tulsa

[TTyMiller]

Thanks for the info. Bill it's the heater fan. This was just rebuilt by Mike last year. The fix used to be to tap the bushings and it would start up. Mike said if the fan was not regularly used this would occur.

[BillWilliams]

it with a small amount of light oil first.

Then break into chasing the electrical connections.

[DanOKC]

If the brushes are worn down or if one of them is not at the normal angle they sit at, that can also cause intermittant start. Replacing brushes or cleaning the copper part on the shaft they contact might help. If you can take a thin small screwdriver & lightly push on the back of the brush holder on either brush & it starts up, then that's likely your problem. But as mentioned before, lube the bushings & make sure it spins freely first.

[jgerock]

Mine works intermittantly. I've tried lubricating the motor and looking at the electrical connections. My motor and box seem in really good shape.

The fan either runs or it doesn't.

[powelli]

(nt)