I live in the desert and it is has been in the high 90’s and need AC this time of year. I got into my truck yesterday and turned on the AC and it would not turn on. I have 4 settings 1 being the lowest fan speed and 4 being the highest speed. Settings 1-3 did not working no air movement. I turned to setting 4 and the AC worked but only at half the speed… So the condenser is working… What could be the problem with the other 3 settings. could it be the knob itself of the fan unit inside the dash… Would it be a simple fix?? What are your thoughts… I appreciate your time. and look forward to your response. Steve Yakima, WA
Probably, your blower motor is binding, and so turning slowly and drawing excess current. The excess current combined with too little airflow has burnt out your blower speed resistor pack.
You will need to replace both your blower motor and blower speed resistor pack.
Not familiar with your vehicle, but on many vehicles, it is not unusual for the resistor pack to fail when the blower motor is still OK. Generally, resistor packs are easy to get to and replace, but blower motors on most cars are labor-intensive endeavors. If there is any chance that it is just the resistors, I would risk a new resistor before digging in to replace the blower.
In this case it looks like it was the motor that was the original problem. In other situations, you are right and replacing just the resistor pack will work, but I doubt that is the case in this situation.
The problem with that is that the OP says he gets half the airflow that he should on full speed. Full speed bypasses the resistor pack.