No heat/AC

SCBANKS2020

MEMBER
2007 CHEVROLET HHR
2.4L
2WD
AUTOMATIC
150,000 MILES

The blower motor resistor has been replaced, took the blower motor out and tested it, that works fine, but when I try to turn the heat/AC on, nothing at all, no sound, no heat, no A/C. All the fuses and relays are good as well.

Friday, February 5th, 2021 AT 8:18 AM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

The way this works is the blower motor relay supplies power when you select to have it turned on. Then the circuit is grounded through the switch. So depending on the setting that you have selected the circuit is routed through the resistor and then grounded.

So this means if the relay is ok and sending power to motor and the motor is ok. Then we need to test the ground side by unplugging the blower motor, connecting your meter's red lead to battery positive and then touch the black lead to pin A the orange wire and you should have voltage on your meter depending on the speed setting. So on high you should have 12 volts and then it will be less voltage the lower the setting.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Let me know what questions you have but if you do this and don't have voltage then you have an open in the circuit. It is either the switch itself or the ground itself.

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