Cooling fan issue need help
Thread Starter
Joined: Mar 2008
Posts: 80
Likes: 14
From: Tigard
Cooling fan issue need help
Okay, I need the help of those who are better with the electrics of these cars than I.
I noticed earlier this summer that my ’06 was overheating on hot days in traffic. So I checked and noticed that the cooling fan (passenger side fan, not the AC fan) was not running. The fuse under the dash was good, but the fuse under the hood was bad. Replaced that fuse and the fan worked. Later that day, it wasn’t working again. Both fuses were good. So I replaced the relay. The fan worked.
The next day, the fan was not working AGAIN. So I checked the fuses and they were good. I then went through the whole diagnostic in the service manual and the relay was bad. So I replaced the relay again. But this time, the fan still didn’t work. And I had decided I might need to get a professional involved.
Fast forward to yesterday. I went to watch the Indy cars at PIR and the car was in a lot all day. When I got back to it, the battery (a 15 month old Optima Yellow Top) was completely dead. A fellow race fan had jumper cables. This is when it gets weird. When we hooked up the cables, the cooling fan immediately went on. The car was coldish (74 degree day, not driven for 6 hours) and the car was not running. And yet the fan was running.
Anyway, I drive home, stopping to buy my own jumper cables along the way, not turning off the car. I get home, into the garage, and shut off the car and the cooling fan is running, with the key out of the ignition. Suddenly, the dead battery made sense. I opened the hood and pulled the relay and the fan shut off.
What is going on??? What weirdness is this silly car doing? Ideas? I hope you guys can help, cause if not, it’s off to a shop for more money than I want to spend. But will if I have to.
Ideas??
I noticed earlier this summer that my ’06 was overheating on hot days in traffic. So I checked and noticed that the cooling fan (passenger side fan, not the AC fan) was not running. The fuse under the dash was good, but the fuse under the hood was bad. Replaced that fuse and the fan worked. Later that day, it wasn’t working again. Both fuses were good. So I replaced the relay. The fan worked.
The next day, the fan was not working AGAIN. So I checked the fuses and they were good. I then went through the whole diagnostic in the service manual and the relay was bad. So I replaced the relay again. But this time, the fan still didn’t work. And I had decided I might need to get a professional involved.
Fast forward to yesterday. I went to watch the Indy cars at PIR and the car was in a lot all day. When I got back to it, the battery (a 15 month old Optima Yellow Top) was completely dead. A fellow race fan had jumper cables. This is when it gets weird. When we hooked up the cables, the cooling fan immediately went on. The car was coldish (74 degree day, not driven for 6 hours) and the car was not running. And yet the fan was running.
Anyway, I drive home, stopping to buy my own jumper cables along the way, not turning off the car. I get home, into the garage, and shut off the car and the cooling fan is running, with the key out of the ignition. Suddenly, the dead battery made sense. I opened the hood and pulled the relay and the fan shut off.
What is going on??? What weirdness is this silly car doing? Ideas? I hope you guys can help, cause if not, it’s off to a shop for more money than I want to spend. But will if I have to.
Ideas??
Thread Starter
Joined: Mar 2008
Posts: 80
Likes: 14
From: Tigard
Thank you. Very much.
Interesting update. Putting the relay back in did not cause the fan to restart. No issues since, though I don't think the fan has come on either. I can replace the fan motor But any other ideas I should check?
Interesting update. Putting the relay back in did not cause the fan to restart. No issues since, though I don't think the fan has come on either. I can replace the fan motor But any other ideas I should check?
Thread Starter
Joined: Mar 2008
Posts: 80
Likes: 14
From: Tigard
Cooling fan controller
RockAuto carries several Cooling Fan Controllers, and the have it listed under Cooling System, but I can't find it in my Honda service manual. I thought it might be that, but now I think it's not really the cooling fan, but the cabin climate control fan. Or am I wrong? Or is RockAuto?
Registered User
Joined: Apr 2019
Posts: 6
Likes: 0
From: NORTH-EASTERN AREA
Overheat fixed?
RockAuto carries several Cooling Fan Controllers, and the have it listed under Cooling System, but I can't find it in my Honda service manual. I thought it might be that, but now I think it's not really the cooling fan, but the cabin climate control fan. Or am I wrong? Or is RockAuto?
Joined: Jul 2014
Posts: 13,815
Likes: 1,543
From: Chesterfield VA
How are you measuring coolant temperature and where? The fans should come on when the coolant temperature at the thermostat at the bottom of the radiator reaches 196° to 203°F and turn off when the temperature drops 5 - 15°F from when it came on. As you can see there's a range but the fan switch should be on at 203°F at the bottom of the radiator.
If you measure at the top of the radiator you'll get a false temperature reading in the range of about 10°F so your 210°F if measured up top will be 200° at the bottom and may not trigger the thermostatic switch assuming it's good. It's an easy replacement.
Gasoline engines seem to run most efficiently right about 200°F.
-- Chuck
If you measure at the top of the radiator you'll get a false temperature reading in the range of about 10°F so your 210°F if measured up top will be 200° at the bottom and may not trigger the thermostatic switch assuming it's good. It's an easy replacement.
Gasoline engines seem to run most efficiently right about 200°F.
-- Chuck
Registered User
Joined: Apr 2019
Posts: 6
Likes: 0
From: NORTH-EASTERN AREA
Chuck,
I haven't came to a fix for my overheating problem yet. I do not have a service manual for my 2000 AP1 nor a schematic. I may have to just get a digitial honda service manual from Ebay. For my temperature readings, I have been using the measurement from the ECU with my TorquePro app w/ OBDII Bluetooth adapter. I always have both fans running when I see them work. And just this past week I found them both running after 5 mins from a cold start without the A/C on but after everything was operating temperature the only way I was able to get the fans to kick on was with the A/C turned on. I just posted a thread about my car, if you look under my profile you'll see the thread. I'm looking to get help from the community.
~John
I haven't came to a fix for my overheating problem yet. I do not have a service manual for my 2000 AP1 nor a schematic. I may have to just get a digitial honda service manual from Ebay. For my temperature readings, I have been using the measurement from the ECU with my TorquePro app w/ OBDII Bluetooth adapter. I always have both fans running when I see them work. And just this past week I found them both running after 5 mins from a cold start without the A/C on but after everything was operating temperature the only way I was able to get the fans to kick on was with the A/C turned on. I just posted a thread about my car, if you look under my profile you'll see the thread. I'm looking to get help from the community.
~John
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