Test Q: The Auxiliary Blower Motor Does Not Operate Correctly

PINPOINT TEST Q: THE AUXILIARY BLOWER MOTOR DOES NOT OPERATE CORRECTLY

Q1-Q2:

Q2-Q5:

Q5-Q8:

Q8-Q10:

Q10-Q12:

Q13:

Normal Operation
Under normal operation, ground for the blower motor is provided through circuit 515 (OG/RD) from the blower motor resistor. The blower resistor is grounded through circuit 1205 (BK). The blower motor speed relay coils are supplied through circuit 1004 (LB/RD). Blower motor speed is received by the electronic automatic temperature control (EATC) module from the rear auxiliary control through circuit 1125 (BN). Reference voltage for the blower speed selector resistor is provided by the EATC module through circuit 1381 (WH/LB). The auxiliary blower motor relay coil receives ground from the EATC module through circuit 1371 (TN/OG) if any blower speed but OFF is selected.

In LO, ground for the blower motor is provided through the blower motor resistor.

In MED-LO, blower motor speed relay 3 is grounded by the EATC module through circuit 1372 (PK/BK). Blower motor ground circuit 515 (OG/RD) is connected through one half of the blower motor resistor to circuit 751 (DB/WH). Circuit 751 (DB/WH) is connected through blower motor speed relay 3 to the blower motor resistor through circuit 752 (YE/RD). The blower resistor is grounded through circuit 1205 (BK).

In MED-HI, blower motor relay 2 is grounded by the EATC module through circuit 1373 (GY/YE). Blower motor ground circuit 515 (OG/RD) is connected through blower motor speed relay 2 to circuit 751 (DB/WH). Circuit 751 (DB/WH) is connected through one half of the blower motor resistor to the blower motor resistor to ground circuit 1205 (BK).

In HI, blower motor speed relays 2 and 3 are grounded by the EATC module through circuit 1372 (PK/BK) and 1373 (GY/YE). Blower motor ground circuit 515 (OG/RD) is connected through blower motor speed relay 2 to circuit 751 (DB/WH). Circuit 751 (DB/WH) is connected through blower motor speed relay 3 to the blower motor resistor ground circuit 1205 (BK) by circuit 752 (YE/RD).

Possible Causes
- An open in circuit 1372 (PK/BK), 1373 (GY/YE), 1004 (LB/RD), 751 (DB/WH), 752 (YE/RD) or 515 (OG/RD)
- A short to ground in circuit 1371 (TN/OG), 1372 (PK/BK), 1373 (GY/YE), 515 (OG/RD) or 751 (DB/WH)
- A short to voltage in circuit 536 (BK/LG)
- A short together circuits 751 (DB/WH), 752 (YE/RD) and 515 (OG/RD)
- Auxiliary blower motor relay
- Auxiliary blower motor speed relay 1
- Auxiliary blower motor speed relay 2
- Auxiliary blower motor speed relay 3
- Auxiliary blower motor resistor
- EATC module