I kind of wish you mentioned that in the beginning.

Here is how the transistor works, your blower motor constantly gets power. The power transistor is a variable resistor on the ground wire of the blower. The resistance changes so the fan motor will spin different speeds.

The wiring test is pretty simple.

#1. The blower transistor has 4 wires. On the transistor electrical connector check that the blk wire has continuity to ground.

#2. Check for continuity between the orn/blk wire of the transistor electrical connector and ground.

#3. Check for continuity between the blu/red wire on the blower transistor and the blu/red wire (same wire) on the 8-pin connector of the HVAC control unit. The HVAC control unit 8-pin connector should only have on red/blu wire.

#4. Check that same red/blu wire on the HVAC control unit electrical connector for continuity to ground.

 

I need to provide more information. Below is the numbering for the blower transistor. There is no wire in the 2 position.


1 and 4 are blu/red, 3 is orn/blk, and 4 is blk.

For test #3 above, you want to test on the blu/red wire at pin 1.

Also, you can test the resistance between pins 1 and 4 on the actual transistor. It should be between 1.4-1.5 kOhms

 

Sorry about that, but i just noticed it this evening when doing that hVAC diagnostic and was looking thru another thread when someone asked that question about all or nothing on the speed.

 

Its not a big deal.

I would have suggested the HVAC self-diagnostic test and the blower resistor tests first. The other tests hopefully would help someone else with the same car as yours in the future (If people would search the forums on here!).

 

Ok here are results:
Black wire: good ground
Orang/blk: open
Bl/Red to Bl/Red: checked good
HVAC Bl/Red to ground: open

I got 1490 ohms on Pins 1 to 4 on transistor. Planning on picking up a used one tomorrow at junk yard. Finally found a used one. How do these numbers look?

 

First of all let me PAHonda and TexasHonda a big THANK YOU! Your help allowed me to fix this problem. Without it I wouldnt have got it done. SO, THANK YOU AGAIN! After pages of troubleshooting, it was determined that i needed the elusive Blower Motor Resistor. After looking for a new one at $95.00, I determined that a used one would suffice. So after wasting trips to salvage yards due to the same year model having a different style plug, let me offer up this advice. THE HVAC Digital Controller has a square plug with 2 pins over 2 pins in the connector. The standard analog AC control system has a flat plug with 4 wires in a row. So before wasting gas driving from Salavage yard to yard, ask the mechanic or worker if they could look at before you drive out. It is easy to see, passenger side. outboard side, look straight up on the firewall side of motor and you will see the flat plug or square plug I t may save you some time and money. I was able to purchase teh blower resistor for $15.00!!!!! Got home spent 10-15 minutes reinstalled the new/used resistor and closing up a few other panels. Started vehicle, the fans came on and ran continuous as they should with AC switch on. The ac clutch engaged and ran as it should. The system was porperly seriviced with correct amout of refridgerant before other problems arose. The AC system is blowind 48 DEGREES F while sitting in driveway. The problems have been solved. Again thanks a bunch, and although I did get some info from the DIY section, there is valuable trooubleshooting ideas in this thread from the guys listed above. They know their stuff. THANKS AGAIN!

 

I'm glad you got it fixed.

Thanks for posting a detailed explanation of your repair. This should help other members if they have the same problem you had.