Low a/c fan speeds not working?

thedudebrah · Jul 27, 2013

08 F350 XL. Since I bought it, settings 1 and 2 on the fan have not worked when "max a/c" is on. They work when I just have the vent on, but only blow cool air when the truck is moving. Anyone ever heard of this before? Anyone know how to fix it?

Big Angry Hillbilly · Jul 27, 2013

Blower resistor most likely.

Mine just quit on '2' this week. Been not working on '1' for a while. Looks like its time to change it out lol.

thedudebrah · Jul 27, 2013

I'll look into it, thanks!

Atsah · Jul 27, 2013

thedudebrah said:
08 F350 XL. Since I bought it, settings 1 and 2 on the fan have not worked when "max a/c" is on. They work when I just have the vent on, but only blow cool air when the truck is moving. Anyone ever heard of this before? Anyone know how to fix it?

So your saying 1 and 2 work when just AC is on but don't when MAX AC is on?

As said above, I would say your resistor is gone but 1 and 2 would not work wether it was on MAX AC, regular AC, fan or heat if that was your issue..

Big Angry Hillbilly · Jul 27, 2013

I flat rate read the original post lol.

WoodBoy · Jul 28, 2013

Yeah I would start with the resistor too but like atsah I have never heard of it working and not at the same time

thedudebrah · Jul 29, 2013

Atsah said:
So your saying 1 and 2 work when just AC is on but don't when MAX AC is on?

As said above, I would say your resistor is gone but 1 and 2 would not work wether it was on MAX AC, regular AC, fan or heat if that was your issue..

Correct. When the MAX AC is on, I also can't turn off the AC and recirculate buttons, but I just assumed this was normal? It hasn't bugged me too much so I haven't dug into it too far.

When the regular vent/ac is on, if I press the recirculate button, nothing comes out of the vents.

I'll try the heat out tonight, it's been kinda hot here so I haven't bothered trying it.

Atsah · Jul 29, 2013

thedudebrah said:
Correct. When the MAX AC is on, I also can't turn off the AC and recirculate buttons, but I just assumed this was normal? It hasn't bugged me too much so I haven't dug into it too far.

When the regular vent/ac is on, if I press the recirculate button, nothing comes out of the vents.

I'll try the heat out tonight, it's been kinda hot here so I haven't bothered trying it.

MAX AC recirulates the inside air so you can't shut the recirulate off when MAX is on.. Interesting.. My 2012 is probably the same, I'll go check it in a little bit to see what mine does... I'm thinking maybe you have a problem with control unit but IDK..

Atsah · Jul 29, 2013

Okay on my truck, you "can" turn recirulate with regular AC so there is something screwed up there.. My guess would be you have maybe a blend door issue or maybe a head unit issue and I would guess the resistor is not right so If it were me I would swap out the resistor first and see what happens.. I don't know enough about the unit iteself to help much, maybe someone else with an 08-10 year truck can help..