ok so two days in a row my car has gotten up to about 75-80% on the temp gauge on the way home from work.
i come home from work about midnight, drive in about 3pm when its usually the warmest part of the day and have no issues on the way to work but its over heated twice at the same exact point on my way home.
only happens when i jump off the highway near my house, and it climbs rapidly. i’ve checked the fluid and its fine, heat works fine, not sure if the fan kicks on or not because in the year i’ve owned the car i’ve never heard it on, but it has never overheated.
so any insights on wtf might be going on here, why would it over heat when its colder and not when its like 85-90 out.
And just to make sure it wasn’t being wierd because i don’t have to slow down at work until i pull into the garage i pulled in the second day and let it idle for about 15 minutes in the garage and it didn’t even move at all. i also let it run today in the drive way at idle for about 35 minutes normal operating temp the whole time and fan never turned on.
i personally get the thermostat changed and the rad cap as a “first step”
make sure u go OEM Thermostat b/c we have alot of ploblems with aftermarket ones at my shop
changing the rad cap will ensure u have good pressure in the rad also.
if the cooling system has no pressure the boiling point is lower so u might be gettting some air after a hot run on the highway followed by a stop or slowing down.
If you are driving, I believe the fans will shut off after something like 30 mph as the air current from driving is more efficient than the fan actually spinning.
What is the age of the current cooling system? Tstat, rad cap, water pump etc? Are you running coolant, or distilled water? Since you are saying this happens when you are driving, I would lean towards it being your water pump.
The fans don’t shut off at a certain speed, as far as I can tell there’s no way the fan system even knows the speed of the vehicle (know this for sure on RS non/ac systems).
Is there any significant elevation change on your drive? I know strange question, but humor me. Also, any change in driving style there and back?
Typically Honda cooling systems are really good, takes forever to come up to hot enough for the fans to go on while sitting at idle. Fans shouldn’t be going on while driving cause the car shouldn’t get that hot usually.
Often cooling system problems are obvious, but occasionally you’ll run into strange or intermittent problems and they suck to troubleshoot. I went through this on my Subaru recently, it was a nightmare. So far the other advice in this thread seems like a good place to start.
You are correct in saying that the fan switch/coolant temp sensor cannot determine the speed of the vehicle, but the ECU can (VSS sensor). The ecu technically turns the fans on and off. It’s basically like a window switch. If the car is above a specified temperature, and below a certain speed, the fans will kick on.
Fans shouldn’t be going on while driving cause the car shouldn’t get that hot usually.
The reason is it not getting hot is because the air going to the radiator from the car moving a certain speed is more efficient than running the fan.
OP, check out the guide I posted and see if anything from there will help.
[QUOTE=Mishimoto;2148381]You are correct in saying that the fan switch/coolant temp sensor cannot determine the speed of the vehicle, but the ECU can (VSS sensor). The ecu technically turns the fans on and off. It’s basically like a window switch. If the car is above a specified temperature, and below a certain speed, the fans will kick on.
[/QUOTE]
From the research I’ve done and the best I can tell, that is incorrect. While theoretically it makes sense, and may work this way in other cars, that’s not how a DA works.
If you look at the wiring diagrams and read about the system you’ll see that in a car w/o AC the ECU isn’t connected to the fan wiring in any way. Theres physically no way for the ECU to have any input. With non/ac cars it’s pretty obvious how the system works, especially Canadian non/ac cars, that system is the most basic and doesn’t even have a relay or control module. Only a motor and a temp switch connected directly to power and ground w/o any input from the ECU.
In a car w/ AC, the ECU is incorporated (two wires lead from ECU to the AC wiring, which is integrated with the fan wiring), but the best I can tell this wire is purely related to the AC compressor and does not have any control over the radiator fan. The radiator fan control module controls both the radiator fan and the AC fan, but as far as I can tell it does so independently of each other. I would have to spend a lot more time reading over the wiring and how exactly each component, such as the AC clutch switch, AC Diode… works, but the best I can tell the ECU doesn’t change anything based on speed. If you have looked at the DA/DB wiring and know there is some feedback regarding speed, please elaborate and let me know, I’m always trying to learn more about this stuff.
Colin you are correct for our model year Integras and Mishimoto is correct for much newer cars. In our cars the fan controls are purely dependant on coolant temperature to command the on/off of the fans. That is true whether the car has A/C or not. Mishimoto is correct that the ECU is the controlling factor in newer cars but the temperature sender will still command the fan on even at freeway speeds if engine temp rises to high, and it will also trigger the fans on when the a/c has been turned on. More info than you needed Im sure but I was on a roll, sorry.
Don’t forget the AC model cars also factor in oil temp… This is something that Honda did away with on the newer b series cars. Or if it’s still a factor they don’t use the same system (oil temp switch) as the DA/DB.
