Power Transistor HVAC: Testing and Inspection

Power Transistor Test

1. Disconnect the 4P connector from the power transistor




2. Measure the resistance between the No 1 and No 2 terminals of the power transistor It should be about 1.4 - 1.5 kOhm
- If the resistance is within the specifications, go to step 3
- If the resistance is not within the specifications replace the power transistor




3. Carefully release the lock tab on the No 4 terminal (BLU/YEL) (A) in the 4P connector, then remove the terminal and insulate it from body ground
4. Reconnect the 4P connector to the power transistor
5. Supply 12 volts to the No 4 cavity with a jumper wire
6. Turn the ignition switch ON (II), and check that the blower motor runs
- If the blower motor does not run, replace the power transistor
- If the blower motor runs, the power transistor is OK