A/C Fan Speed Knob

This past weekend I took a trip with a friend in his 2009 Prerunner Double Cab.

About 400 miles into the drive, the Air Conditioning Fan Speed Control Knob stopped working in the lower positions. The OFF position worked, and so did the HI position, but nothing in between. The outdoor weather had been 95-105F for the previous few hours.

I don't remember when, either that night or the next day, the Fan Speed knob was working normal again.

What gives?

 

The problem is the fan blower motor resistor not the fan speed controls. The resistor is mounted to the firewall near the blower motor. One of the pins in the connector loses connection and then the only speeds that work are off and hi.

 

What is the fix?

 

Replace the resistor pack and or connector as needed.

 

What are we talking in price and time if my friend does it himself?

 

I did it on a different car before, $35 and 15 minutes, not oem part*

 

Thanks. I see there are several other threads on this topic.

In a couple of them, several people said the A/C air filter being clogged is likely a contributing factor because the resistor and connector don't get enough cold air -- and as a result -- overheat.

I wonder if it would be helpful to switch to a non-OEM higher flow A/C filter?

 

I get my cabin air filters from Amazon for ~$8, replace it every spring, no problems so far. Not sure that would cause the resistor to fail though, I would think the fan motor would fail first by a clogged filter. If your really concerned about it you can run it without a filter too, no real harm in it.

 

In those other threads there is a TSB with a new Resistor and new wires/plug to replace the old melted/burnt wires.

 

I believe their thinking is that the restricted air flow in a clogged filter prevents cold air from blowing over the resistor and connector. Either that, or a clogged filter forces the driver to use the A/C more often, which translates to more resistor and connector heat.

By the way, cabin air filters are much cheaper through RockAuto. Amazon sells the

$17 TYC 800038P Toyota/Pontiac Replacement Cabin Air Filter

TYC 800038P filter for $7.78, but at RockAuto it's $3.48. Even with shipping, the price is still much less if you buy in quantity. I think I'll create a new thread on this topic. I myself am guilty of paying Amazon prices assuming they're the cheapest, but that's not always true.

 

A blocked fan draws less current than an unblocked fan. Less current equals less heat.

Just so you know. Strange but true facts. The fan is doing less work. Less work equals less heat.