Fix Honda Blower that doesn’t work
Honda vehicles don’t use a traditional blower motor resistor setup to regulate blower motor speeds. So if the blower motor doesn’t work on your Honda, you’ll have to check out the blower motor power transistor instead. The Honda blower motor receivers power form the blower motor relay. Power flows to and through the motor, but the power transistor controls the connection to ground to regulate the blower speed. The blower motor power transistor receives a pulsed voltage blower speed signal from the heater control and that turns the blower motor transistor on and off to pulse the ground connection on and off in rapid succession to adjust blower motor speeds.
If your blower motor doesn’t work, first check the blower motor fuse. Then check to see if you get battery power coming into the blower motor from the relay with the key in the RUN position. Next, check for pulsed voltage to the power transitor on the blue/yellow wire (you really should use a scope to check that). If there’s no signal, remove the blue/yellow wire from connector and use an old style incandescent bulb test light. Connect the clip to ground and touch the test light probe to the terminal where the blue/yellow wire connected. With the key in the RUN position and test light touching the terminal, the blower should work if the transistor is good. If the blower motor doesn’t work, replace the transistor
© 2012 Rick Muscoplat