Intermittent Loss of A/C Request Blower on Speed 2, 3, or 4 - keywords air conditioning inoperative lamp light switch

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Loss of A/C request (LED on switch turns off) with the blower speed on 2, 3 or 4, and/or no blower operation on speeds 1 and/or 2 and/or 3. The A/C compressor will not turn on until the HVAC control module sees that the blower motor has been turned on. The HVAC control module sends 12 volts out on circuit 60 (Yellow wire connector C1 pin 20) and monitors the voltage. When the voltage on circuit 60 is pulled low, the HVAC control module will allow the A/C compressor to turn on.

1. Disconnect the Blower motor resistor, and use an ohm meter and check for an open circuit between Pin B and D on the blower motor resistor. If the resistor is open (OL) replace the blower motor resistor. If the resistor is not open (OL) go to step 2.
2. With the blower motor resistor still unplugged,

•	Ignition on

•

AC on

•	BLOWER MOTOR OFF

•	use a voltmeter and check for battery voltage on circuit 60 Yellow wire pin D on the blower motor resistor Harness connector. If there is no battery voltage at pin D check circuit 60 for an open. If there is battery voltage at pin D, then perform a pin drag test on circuit 60.

3. If there is no battery voltage on circuit 60 Yellow wire, and the circuit is not open, then replace the HVAC control module.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.