Raduque

So I just recharged my AC a couple or 3 months ago and it was working fine till a few days ago. Now, I only have the lowest blower speed no matter which speed setting I turn the knob to, and it doesn't speed up when I select recirc. I keep it on vent though because driving at 40mph or so pushes more air through the vents than the blower does.

Which is more likely: resistor, blower motor, or controls?

08 2LT 2.4 auto 156,500 miles.

greg8453

Hit the motor with 12 volts. If it don't blow you found your problem.

Oldblue

Change the resistor first, look for burn marks on the back of the hvac control panel, if they are charred, replace it. If the fan is working, it’s not the fan.

PulpFriction

Blown resistor pack is common on many GM models, and the fan working only on certain speeds is the symptom.

donbrew

Only on HIGH when selected is symptom of bad resistor. the stated problem is low speed on any switch position; I don't know how that is possible, without some external wiring changes.
The speed is regulated by the path to ground, I don't see any way that all of the contacts in the switch could lead to only one of the resistors in the pac.
Has any one done ANY electrical installation or messing with wires?

BTW, recirc should have no effect on fan speed, it does turn the AC compressor on and is only available if the fan is on and on upper vents mode. Specifics in the Owner Manual (link in my sig).

RJ_RS_SS_350

The lowest setting on the fan speed switch is "off". In recirculating, this position completely blocks air flow. Changing back to fresh(outside) air(what you are calling "vent") allows some air to flow, as you have noted, higher vehicle speed = more air flow. Sounds like the fan is not operating at all. Which brings you back to Greg's suggestion, apply 12 volts directly to the fan motor. Or (donbrew) does it operate by applying ground?

Raduque

Maybe it's just because the outside air vent gets closed, but before this issue, when I press the recirc button, it feels like more air is being blown out the vents, and the fan sounds louder. And yes, the problem is when I turn the blower on, it only runs on it's lowest speed.

Edit to address the bolded: No, no electrical work at all except replacing the battery 3-5 months ago.

The fan is definitely running, because I can feel air from the vents at a stop/parked, and I can hear the fan running. It simply runs on it's lowest "on" speed, no matter what I turn the knob to (except for off, that actually turns it off).

I will do some troubleshooting on Tuesday next week, because I work the next 3 days

RJ_RS_SS_350

Thanks for clarifying that. Like Oldblue said, check the control panel for burns. You should be able to find a replacement at a wrecking yard.

Oldblue

Pick a part or EBay

donbrew

The fan motor is "always" hot. The switch provides ground through the resistor pac.
The only I can think for this symptom is the knob is not turning the selector, just free turning making you think it is changing speed.
Yes, the fan sounds louder when in recirc because it is drawing air from inside. Have you ever replaced the icabin air filter? Most people are not aware of its existence, if it is in the Owner Manual it is well hidden.