answersLogoWhite
Auto Parts and Repairs
Heater Cores and Blower Fans
Chevy Trailblazer

How do you figure out why the heater and blower work but the ac and defroster do not?


Top Answer
User Avatar
Wiki User
2011-09-13 01:33:33
2011-09-13 01:33:33

The HVAC doors that control the airflow are activated by small vacuum motors. The system is designed to fail safe; this means that the system will fail in full defrost mode. So, knowing this and the fact that you have heater but no A/C or defrost you should assume the system has a failed control head (the part that you select functions with with button or lever). Or the doors are stuck due to an warped duct system (usually high heat related).

Related Questions

User Avatar

Why the heater or defroster may not work in a 1993 Chevy Caprice Classic because of the heating core is going out.

User Avatar

There are multiple reasons why the passenger heater on a 2007 Chrysler Pacifica may not work. it could be a heater coil, a fuse, or the blower. A mechanic can help figure out the specific reason.

User Avatar

Depends on what you mean by heater will not work. If the blower motor will not work, it can be a blown fuse, bad blower motor, bad blower motor switch, or a defective blower motor resistor pack. If you mean that the blower motor works but there is no heat, then it can be a clogged heater core, thermostat stuck open, or defective heater control valve.

User Avatar

There might be a bad fuse causing the heater to not work. Check the fuses if they are all ok you may have a bad blower motor. when you turn the heater on and no air is blowing then it is your blower motor.


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.