I have a 2000 Toyota Avalon. The A/C will only come on if the switch is turned to full blast, but even then it makes a really loud grinding noise and does not blow very cold air. Is this a compressor issue or blower motor? I am assuming the switch is bad since it only works on highest speed, but could it be something else causing this also?
If the HVAC’s blower motor only runs on Hi and makes noise, the first place to check is the blower motor, its housing (crammed with debris?) and the resistor that, if working, allows several different fan speeds. With luck, therein lies the problem, less costly than a compressor. Best wishes.
You should be able to pinpoint where the noise is coming from.
Open the hood and have the AC on high. If the sound seems to be coming from behind the glovebox…it’s the blower motor. If it’s from the compressor it will sound loudest under the hood…near the compressor.
Good ideas above. I’m guessing you might have something binding up the blower fan in the passenger compartment. That would put more current draw on the fan, and could burn out the circuitry which slows it down or speeds it up as you change the switch for the blower speed. On cars that do this with blower resistors, they almost always stop working at the low speeds and keep working on the high speeds, b/c to run the blower at a low speed the blower resistor has to take a lot of the power, while at a high speed setting the fan motor takes on most of the power, giving the resistor a break. And all this would be worse if the blower wasn’t spinning freely.