Hi, I'am totally new to user forums, so any mistakes, please forgive me. I have a 2007 Honda Accord and love the car, only problem is a couple of weeks ago the heater/climate control fan stopped working. I was told that the problem may be with the Fan transistor. I did prove out the fan which does work, so replaced the transistor and the thermal fuse. Now when I switch the ignition ON, and without pressing the fan/Ac on buttons the fan comes on and I cannot switch it off. The temp controls work up and down correctly, but just does not switch off.
Any help will be appreciated, Thanks in advance.

 

I wrote something about troubleshooting that circuit. But I don't know how different the 2007 might be...
https://www.hondaaccordforum.com/for...-2006-a-36131/

 

Hi Jim, Thanks for your Help. I have had a look at your previous post and the information is very useful. Since I was going to buy a replacement transistor, I could not find any body selling this apart from the main Honda dealer. I carried on to strip down the transistor module, This had a power transistor and the thermal fuse on the board with some resistors. I moved on to replace the transistor and the thermal fuse. plugged back into the car and the blower comes ON straight away and does NOT switch OFF. Could it be that the transistor is U/S? or could this be a stuck relay?

 

try checking the relay ( if there is one). They can go bad or get flakey...
carbon on the contacts, broken springs, or weak solenoids.

 

probably not the relay, the blower resistor (transistor) is a weak point in these systems, not sure about the 07 model, but the 0306 is coupe/sedan specific with climate control. cudos for trying to rebuild yours but these things live in a high temp harsh enviroment (reason the heat sink is so big) you'd be best off just finding a used one or get one from the dealer. i'm guessing you're not from the US, over here, the aftermarket parts houses have them.

 

The fan speed control circuit is same for 2003-2007 in my shop manual. Fan is hot all the time and transistor provides a variable resistance to ground. If you know the transistor is good, then bias must be commanding full fan speed. This would indicate a problem w/ the HVAC panel.

There are separate diagnositics for the system that can be interrogated manually. Following is brief summary. I would suggest purchasing a shop manual. check ebay seller automanualsource for an inexpensive emanual.

1) Turn Ignition Off
2) Turn Fan Switch Off
3) Set Temp dial to Max Cool, push mode control to select Vent
4) Turn ignition switch On
5) Press and hold the recirculation button
6) While holding button down, press the rear window defogger button 5 times w/i 10 secs. The recirculation button blinks 2 times and the self diagnosis begins: short flashes indicate code. A/C Indicatator may also flash codes 7 & 8.
7) Turn ignition Off to cancel self diagnosis

Post back for decode of flashes or get manual.

good luck