I have a 93 3vze,sr5 pickup and the other day after a few minutes of it warming up, i turned on the defrost and a loud grind/knock came on near the glove box...
Heater fan? Is that serious? It only happened once so far but kinda sounding weird
Thanks!

 

A lot of trash gets in thru the windshield cowl and eventually gets down to the blower motor. You can pull the blower out and get the trash out of the fan assembly. Look into the cowl and see if you have leaves and other things sitting in the compartment. If so, you can remove the cowl and clean it out. There are just 3 screws that hold the blower motor in and that will fix the noise. Just posting to show how bad other things can get.

If it is bad enough, you can remove your mud flap, and loosen the inner fender on the rear of the fender and probably have a lot of debris there as well.

My experience.
Condenser was dirty. This truck has been well taken care of. It might look like some of the junk trucks I have worked on in the past, but this is common on nice daily drivers as well. It is from not having Vent Screens on the windshield cowl.


Here is the resistor that controls some speeds for the blower. I havent seen one like this as it is not typical. I wonder if it was someones cheap fix. Mark says he has found replacements on Rockauto for $8. I will be checking that site later today for one.


Another common problem of debri getting into the windshield cowl. You can hear the debri alot of times in the blower.


There is alot of dust from the brushes inside the motor. I take an air hose and clean it out. Also cleaned the fan blade assembly.


You cant see in the picture, but you can actually see brass windings in there. It was dusty. Nice and clean now.


Cleaned the Condenser, make sure drain is clear as well. Washing the condenser wasnt a problem as it is always wet. I soaked the coils in Simple Green and then rinsed with water and an air hose. You can see thru it now.


Here is how it sits in the truck. You can take just the Blower Assembly out by its self, but is difficult. If you pull the AC Condenser out, the Blower comes out so much easier. You will need to recharge the system. I dont know if this truck has been converted from R12 to 134. Will need to look and see about that later. Put Blower in first THEN Condenser.

 

Thanks for the detailed message! I will check those things out...it hasnt made that noise again but still good to dbl check everything