Auto Parts and Repairs
Air Conditioning and Coolant
Late Model 1979-New Ford Mustangs

Why would your AC not come on when you turn the knob?


Top Answer
User Avatar
Wiki User
2004-09-22 16:19:00
2004-09-22 16:19:00

You either have a bad switch or you need to check your fuse or relay for your a/c. To check your switch: you need a multimeter or voltmeter. You'll need to get to the back of your switch, keep it plugged in and find your power wire to the switch. Then put the positive end of the voltmeter in the back of the connector into the power(don't push to hard or you'll damage the connector). Then put the negative end of the voltmeter on a good ground on your frame or something that touches your frame. You should get a voltage reading of 12 volts. If there's no voltage than somethings wrong with the wiring up to your switch. If there is voltage, than you need a new switch.


Related Questions

User Avatar

could be a bad fuse or ac relay,also if out off coolant ac clutch will not work,

User Avatar

The first knob controls the fan speed. The second selects the temperature. The third selects which vent it will come out of. And the last will select recirculated or outside air. Turning them all to the left will give you max AC.

User Avatar

the control is electrical i do believe so you would need to replace the switch. the switch is behind the knob you turn. of course you will need to remove some parts to get to it.

User Avatar

does the ac just stop or does the defrost also come on out of the blue?

Copyright © 2020 Multiply Media, LLC. All Rights Reserved. The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Multiply.