2004 Accord V6

When engine is turned on, the radiator fan comes on immediately (is this normal?). When engine is turned off, the radiator fan stays on (shutting off within 10-20 minutes). Is this normal?

I've had car for 4+ years and only started noticing the fan staying on recently (within last couple months).

From what I've read (and from what seems logical), the fan should only run when the car thinks the coolant temperature is lower than the engine temperature. It doesn't make sense that it would start running immediately (on a cool day). It also doesn't make sense that it would run after engine is shut off when engine is turned on for 15 or 30 seconds.

I took it to Honda dealer on Saturday. They couldn't diagnose problem and said I needed to bring it back during week so they could contact Honda Tech line. They thought it might be related to PCM (ECM?).

It sounds like it could be ECT sensor, but Honda Service said it tested OK.

Any ideas?

 

its possilbe that the fan relay is sticking. i dont think that is normal

 

I did try swapping the fan relay with another identical relay in the fuse box and it has no effect on the problem.

 

Do Accords still have fan timers? They were a common cause for this in earlier models.

 

It would be helpful to know where the OP lives. But one fan shouldn't be on all the time like that. You either have a bad coolant switch or a relay sticking on (for a number of reasons)

 

I live in the Los Angeles area. The outside temperature has been very moderate. Over the weekend, I started the car in the morning (with temp in low 60's) and let it run for 15-30 seconds. I see the fan starts running immediately. I shut off the car and the fan runs for another one to two minutes.

At other times when the car has been driven for some length of time, it might take 10-20 minutes to shut off.

Does anyone know exactly what has to happen for the fan to start running and to stop running? For example, is it normal for the fan to start immediately and/or automatically run when the engine is on? If not (which it sounds like it shouldn't), what has to happen? Does the ECT sensor measure the coolant temperature and send some signal to the fan relay (or the PCM/ECM)? Does the temperature get compared to the engine temperature? Is there a schematic somewhere? How about for the fan to shut off? If the temperature sensor is completely broken, does a fan timer automatically shut it off after a set number of minutes?

You'll have to bear with me. I'm trying to piece together the information I've found searching the internet and this forum. I'm not trying to fix the problem myself. I just want to understand how it works so I know I'm not getting taken advantage of by the dealership's service department when I go back.

Thanks again.

 

I attached a wiring diagram showing you where the fan's power is coming from, so you can trace it back. Sounds like a bad relay. ALLDATAdiy has testing for the individual components, figured this would get you started.

Check out the ALLDATAdiy.com ad here on Honda-Tech: CLICK HERE!

 

I have the same problem now. Both fans stay on forever and kill the battery. Even if I disconnect the battery for an hour and then plug it back in fans turn on immediately. SOMEBODY HELP!!!

 

ok I changed relays in the fusebox under the hood and changed temp sensor switch on the engine block that controls the fan and still have a problem. I do not know what the hell to do now guys.

 

On the turning on immediately, do you have your a/c on? That will cause the fans to turn on immediately. The other problem, I had a 93 accord, and for the last 3 years I owned it the fans had a mind of their own. Sometimes turning on 5 seconds after turning the car off sometimes, 10 minutes, and somtimes turning on then off then on then off... Guess I was just lucky that it never stayed on long enough to kill the battery but in my case never found out what was wrong or needed to fix it.

 

Ac always off. I think ima change all 3 relays and c what happens