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Enes
Enes, VOLVO Master Technician
Category: Volvo
Satisfied Customers: 4911
Experience:  18+YEARS WITH VOLVO AS THE MASTER VOLVO MECHANIC&Ase
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Why is the 2005 Volvo S40 blower inop?

Customer Question

why is the 2005 Volvo S40 blower inop?
Submitted: 1 year ago.
Category: Volvo
Expert:  SARMIENTO22556 replied 1 year ago.

Hello, I will try my best to help you with your concern.

Had the blower motor been noisy up to this point?

do you want to diagnose and repair this yourself?

do you have access to a voltmeter?

Customer: replied 1 year ago.
Had the blower motor been noisy up to this point? not that I remember
do you want to diagnose and repair this yourself? yes
do you have access to a voltmeter? yes
Expert:  SARMIENTO22556 replied 1 year ago.

1. Check fuse F10.

2. At the blower motor, check for battery voltage on terminal 1 (Green/Orange wire). Check for ground on terminal 6 (Black wire).

3. The command signal from the Central Electronic Module (CEM) is sent on terminal 2 (Blue/White wire). This is a 0-12 V PWM signal @ 400 Hz with 16-95% duty cycle, depending on requested speed.

4. Terminal 3 (Green/Yellow wire) is a feedback signal from the blower motor power stage to the CEM. This signal can be one of three:
a) Frequency = 80-600 Hz, 50% duty cycle means the fan is on and operating.
b) Frequency = 12.5 Hz, 50% duty cycle means the fan is OK, but the input signal is outside normal range.
c) Frequency = 0Hz, 100% duty cycle (basically battery voltage) means the fan is OK, but is not active (no signal sent to the power stage).

5. If the signal is present to the blower motor, replace the motor and power stage as an assembly.