Our air/heater fan only blows air when it is set on high. It makes a hooting noise when it first starts like maybe there is something in the way. I have replaced the blower fan relay switch but that had no effect. These were all excellent. I had to replace both the resistor pack and the blower fan motor. The video on youtube was great help also. + I definitely agree with the answer from rj713 and just want to add to it. Remember though that bad resistors can be caused by blower motors with a lot of mileage on them.They build up higher resistance and that extra draw can destroy resistor. replacing the resistor may solve the problem for the short time but may re-occur. If that should happen, you may need a new blower motor. To get to the resistor, open your glove box, squeeze in both sides and let it drop down. You should now see the resistor directly behind there. It is about 3" x 1.5" with a 5/16 screw on each end and two wiring connectors. (one big one small). There is also a thermal fuse that I would replace as well since you are already there and the price for it is minor.

It is a thermal fuse that goes bad often. So you could replace that as well, but it needs to be soldered. for your resistor repair, there is a Video that will help you with it. commercial ac unit pricethe part is readily available at places like this Hope this helps, and I did not mean to bump rj713's answer, but can not attach images to comments. how many kwh does a window ac unit use I've had similar problems with my truck. smallest size ac unitYou will find there is a resistor pack that divides voltage to the fan controlling fan speed. High speed bypasses the pack which is why it still works. The startup noise could very well indicate failing fan bearings--that could have caused the burnout of the resistor pack. The pack usually cost about $20 and is fairly easy to replace--look for it near the fan assembly.