2002 Honda Civic LX 225678 miles automatic, somedays it runs fine no problems for a week or two then it will overheat. usually the fans don't come on. But when i test the fans with a jumper they work. I had the timing belt and water pump changed a month or two before the problem started. i took it to a locale shop and they checked it (radiator relays ect.) and ran the car for 4 hours and it would not overheat i dove it for a week after that then went to lunch and it started to overheat.
There may be a separate thermal switch that operates the fans that is failing intermittently. (Do the fans come on with AC when that happens? On most cars that will engage the fans regardless of engine temperature.) Fan relay and associated wiring and control circuitry are also suspect on a 20-year-old car and may have intermittent faults. If all else fails, since the fans are working you could do what Scotty has shown in his videos and put in your own circuit with a switch inside the car to manually turn on the fans when needed.
Yes the fans come on when i turn on the a/c
That suggests the temperature switch that turns on the fans according to engine temperature, or its wiring, is defective. Does the car still overheat if you turn on the AC to engage the fans?
If you unplugged the fan switch and jumped the 2 terminals on the wiring connector and the fans worked then that pretty much narrows it down to either the fan switch itself or its wiring connector.
Inspect the wiring and the connector terminals on the connector. If they look good then it's probably the fan switch.
i changed the switch and thermostat still have problem
Check the fan control module. Also check fuses and relays.
checked the fuses and relays, any ideal where the fan control module would be?
Based on your responses, The fans may not be the problem after all. When it last "started to overheat" did you open the hood while the engine was running to see if both cooling fans were operating at the time?
What was the solution when it last started to overheat?
Do you think there could be an intermittent problem with the temp. gauge? A scan tool can read the coolant temp. to verify an accurately reading gauge.
Take a look at this. The jumper test you did only shows the fan motor is working.
Do you know if a new thermostat was installed when the water pump was replaced?
https://www.aa1car.com/library/electric_cooling_fan.htm
new thermostat and fan switch
i bought a gage that plugs into the obd2 and i have it set on the engine coolant temp, an alarm goes off at 217 F then i have time to get off the road most of the time its at 188 to 203 F. then it does fail again and the fans are not spinning what should i check? and thanks for all your help.
Intermittent problems are very frustrating. If I understand correctly, it has to be the fan switch, the connection or the wiring like @jack62 said. I would try gently wiggling the wires and connector while the fans are running to see if they cut off. If the overheating/fan failure occurred before and after replacing the fan switch, then I doubt it's the switch.
It is a 20 years oldcar. The computer might be acting up. It might be a good idea to disconnect the fan relay and install a switch to control the fans manually.
