2003 Accord EX V6 Sedan. Replaced Heater blower motor (for the sedan); resistor (for the sedan); relay, obviously all fuses are good otherwise it wouldn't be blowing on high. I'm suspecting the next component would be the controller within the dash below the radio?

Thanks in advance
Tim

 

Update to my troubleshooting. Seem when i took the climate controller out of the center console (disconnected) and i started the car, the blower runs high as well.

 

With the ignition turned ON, the positive side (+) of the blower motor wiring is always hot if the blower motor relay is working properly and fuses are good. The issue you're having is at the ground side.

The negative ground (-) source goes through the blower motor power transistor. If you unplugged the climate control unit and it still ran, you likely have a short in the power transistor or the wiring related to the ground side.

 

There are 4 wires to the Resistor. Do you have the schematic to this?

 

See attached:

 

Is it possible receive bad Transistor?

 

But a short would allow the system to work good for a bit till it failed again.

 

Yes, it is possible to get faulty replacement parts.

A ground side short will generally cause it to run all the time when the ignition is turned on (as previously mentioned, power (+) will be present with the ignition in the ON position). Applying or removing the ground (-) side or limiting the ground through the resistor is what controls the blower motor speeds and operation.

An intermittent ground short would causing to intermittently run.

 

If it worked fine after the replacement of the transistor, the replacement may have gone bad now.

 

Received bad from the auto parts store? Or...Part is failing due to short?

 

First off i want to thank you for your time helping me isolate this issue. I've sent in the controller to be tested & checked to validate it's working order. Please look over the WD at the Blower Power Transistor. Reading the Transistor only, I'm getting a good reading at pins 3 & 4 @ 1.5 ohms, but it is reading continuity between pins 2 & 4. No continuity @ pins 1 & 2. Does that switch stay contacted all the time having power through the diode? Or should it release when power is open at pin 1?

My thoughts is the "NEW" transistor may have failed internally causing the ground between pins 2 & 4 allowing the fan to blow full high. Your thoughts?

Thanks
Tim

 

Update to my troubleshooting. The Power Transistor was bad from the auto parts store. Tested per the wiring diagram and Pins 2 & 4 had a ground, which it is not suppose to, that caused the fan to blow on high all the time. Swapped out the unit and it works fine. I turned in the climate controller to have it tested and checked. Will get that back end of the week.

 

Updated: The Four Seasons New A/C Heater Blower Motor 75735 purchased from AutoZone is drawing too many amps from the Power Transistor burning out the PT. When replacing the Blower motor please use your best judgement to use OEM parts when it comes to electrical units as aftermarket components don't comply with the correct limit requirements.