Honda Car Forum

Last night my wife informed me that the blower in her 2002 CRV was not working. My first thought (and hope) was a blown fuse, but then she explained that when she started the car, it wasn't working. A few minutes later, it came on, then went off after about a minute. Shortly thereafter she was home. I went to check it out a few hours later, and when I started the car, the blower worked for a minute, but then quit. I poked around under the hood at the fuses & relays for a while, even pulled the fan relay (it was rather warm to the touch, even though I had only been trying to run the blower for about 5 or 6 minutes) and checked the coil resistance (98 ohms) and cycled the relay with a 9-volt battery (did not think to check that it was actually closing the circuit). Put the relay back in, started the car, and again the blower worked for a minute then quit.

I've read through the diagnostic techniques for the transistor and motor, and I'm confident in my abilities to do said tests (plan on doing those tonite), and even replace either or both parts. Beyond that, though, I'm humble enough to think I could be getting in over my head if I need to tear things apart any further. Did anything I described above suggest that there could be something else going on here other than the transistor or motor? The intermittent operation makes me think of some sort of self-resetting thermal fuse, but I don't believe there is one anywhere in the circuit.

Thank you in advance for your help.

So for an update... I got home from work, planning to look into the blower issues, and when I fired up the CRV, the blower was working (somewhat expected). But then a funny thing happened while I was waiting for it to quit. Basically, it never did, even after waiting roughly 15 minutes. By then it was time for dinner, so I retreated for the evening. Not sure what to do next, just wait for it to stop working again I suppose. In the meantime, does anyone have any insight, based on these two posts?

Hi.

The next time it quits, reach under the dash and smack the blower motor. If it comes back on, you need a blower motor. Also, pull the blower motor connector off and check for signs of overheating, If that all checks out, you need a new transistor.

Hope that helps.

Thanks DELuth. I guess that's about all one can really do when it is operating intermittently like this. I guess it's that intermittent operation that has me really thrown for a loop. For the motor itself, I suppose I could understand an intermittent failure, but for the transistor, doesn't it seem more likely that it would fail completely and decisively, rather than sometimes work, and other times not?

You are correct, the transistor usually dies and stays dead. That is why I suggested starting with the other checks first.

So today I got some time to tear into it. My wife drove the car yesterday, and said that the fan came on for a couple minutes, then died and never came back. It was not working today when I went out to look at it, and wacking the blower motor did not help. Resistance across pins 3 & 4 on the power transistor checked out OK, about 1.43 kOhms. No signs of burning on the blower motor harness. I pulled the transistor, and popped the cover off. Found the forward resistance on the transistor to be .943 MOhms, and an open circuit condition for the reverse resistance. Also found that the thermal cutoff inside the transistor was open, so I replaced the power transistor, and everything is working good right now. I can only surmise that the transistor was having issues (while the blower was operating intermittently), and then the TCO finally blew. Since, as I understand it, the TCO is not resettable, it couldn't have been blown previously, and the blower still able to work. Also changed the cabin air filters, which were very dirty. I imagine this couldn't have helped things any.