91 accord 249k miles, 4th owner, recent purchase for daughter.
Read lots of different opinions about the twin fans running after the engine is shut off. Some posts say if it runs at all after shut down - there is a problem with cooling. Some say it is supposed to run to cool radiator. Still others say it can run up to 6 minutes. In my case, the fans run intermittently. Most of the time they run about 5-8 minutes then shut off. At other times, after short trips, the fans don't run on at all. At this point, I'm not sure how to proceed if at all on the issue. Any insight is appreciated.

 

Essentially, after the car is shut off and the coolant temperature at Thermo-switch B (located at or near the upper coolant hose housing on the engine block) reaches approx. 223 degrees F, then the radiator fan come for a set amount of time. The fan sometimes coming on after shut off is normal if it is really hot (e.g., summer time, very hot conditions, etc.) If it comes on all the time or most of the time or stays on too long, then there may be a problem.

This link has info. regarding the radiator fan running after shut-off.

Overheating Troubleshoot for Honda's Cooling System

 

It is a bit debated on if it is normal or not.

It has to do with having an automatic transmission although I forgot the reason.

I will share my experience with you.

I used to have an auto in my car with the auto ECU and mine did just as you describe.

Most of the time after trips the fans would turn on for about 5 mins ater I parked the car.

My car never had cooling issues, I keep my car in tip top shape.

I switched the trans out to a manual and installed the manual transmission now my fans have never ran after I parked it.

My car still runs at the same temp as it did before nothing different except for the 5 speed ECU.

I have the opinion that you should not worry about it. It seems to be normal, or at least normal for some Accords.

 

This is where my experience differs.

I know my thermo switch B works correctly. When I had the Auto as well as now with the 5 Speed ECU my fans hardly ever come on. really only on very hot days or while running the car while it is not moving for a bit.

If thermo switch B was at 220+ my fans would have been on before I parked.

Unless it is possible that an air pocket forms there when the water pump turns off and it steams the thermo switch?

Either way my car has never ran hot and I consider it a non-issue. IMHO YMMV

 

The reason for the higher setpoint for the other switch, is that after turning off the engine, the coolant naturally circulates by its own buoyancy. It CAN get hotter in the first few minutes after shutting off the engine.

When the waterpump isn't pumping, the hottest part would be the head. So they put the switch in the outlet water nozzle.

When the waterpump IS running, it's all well-mixed and circulating by force. So the best mixed temperature is at the thermostat.

 

Jim - any thoughts on why mine stopped running after I changed my ECU to a 5 Speed ECU.

I did not change any of my sensors.

My fans have not run 1 times since the swap.

Weird, huh?

 

Sorry, about all I have to say about this


https://www.hondaaccordforum.com/for...similar-44973/

As Jim said, thermo b is "set" higher to cover the increase in temp as the engine trys to cool. Jump the wires on thermo b (key off) just to be sure "the fan" (only time a 3rd, 4th,5th gen a single fan runs) comes on....then if you are worried, an IFR temp reader or boiling the sensor will be needed.

 

The fan on my 95 manual transmission accord would turn on after I turned off the engine. The timer is set to turn off the fan after ~15 minutes or if the temperature of the engine drops below 223F. Only the radiator fan turns on to do this (the passenger side on the 4-cylinder accord).

 

I don't know why it would be different now. There's a fan timer module that contains the switching logic for that, but you didn't change that (or did you??)

Got a shop manual? On newer Accords the ECU is involved in those circuits somehow, but I don't know what year that started.

 

I did not change anything but my transmission (from auto to 5 speed) and the ECU (from auto to 5 speed) everything else is 100% the same.

Also I had no stored codes before the swap (I checked)

Same motor, same fan timer, same sensors.

There is just one thing that was changed and it was the ECT, I broke my ECT when taking the trans off the motor and replaced it with a junk yard unit.

Unless the ECT has something to do with the circuit (I do not think it does) then I have no idea.

I will say that the fans have not once ran since I made the 5 speed swap and they used to run pretty much 100% of the time after I turned the car off.

Weird, huh?