weak ac fan

[FredFarndon]

the fan (or fans) seem week not blowing out the dash ducts as well as they have. where do I look, is there a filter under my dash maybe that's needing replaced ?
2004 HO 5.9 3500 dually with 289000 miles on it, runs great still.

 

[MarkEagleUSA]

It could be the blower motor resistor. Can you tell if the blower is running in all speeds?

 

[sag2]

There was a "filter" of sorts in the 2006 trucks, not sure about earlier, but it was to block some of the air flow so the back seats got a little less air. You have to pull the dash to cut it out.

 

[Bob4x4]

If you spend much time in the dirt the face of the evaporator can get severely restricted.Coming home from Baja I lost all flow.You can drop the blower motor out to clean it.

 

[Wiredawg]

Another way to clean it is add extension hose to the drain and use hot water to rinse and drain. We've had pollen and dust problems we live down a gravel road.

Add a little Lysol or Fabreze and get better smell.

Cheers, Ron

 

[EDankievitch]

Check the key switch they have a tendency of overheating and burning the connection at the plug.

 

[Tuesdak]

More diagnosis is needed. The above covered some things.

These systems are known to snap doors broken. Check for airflow out of defroster or heater ducts.

Electrical: Check blower motor resistor for a crack, burned wires at resistor plug, and motor. Above covered ign switch bad and ign connector as full current goes through the switch. All 4 things can be bad at once. Quick and dirty is to measure battery voltage with blower on high and measure voltage at blower motor. IMO anything over 1 volt lower at the motor is trouble. Be careful as bad connections heat up the wires and connectors that can burn you. IMO I replace blower motor if any wiring or connectors are burned and I do so from the dealer. With a motor replacement I also do the resistor pack and note it's been updated for some years to not crack as much. I don't want a Red Communist knock-off that is noisier than the OEM motor.