Hello everyone - to start Ill mention that I have looked at many older posts regarding this type of issue and am mostly want to confirm my suspicion on what is going on with my Civic.

Radiator fan isnt coming on. I tested the radiator fan switch by alligator clips to the battery… the fan came on. I tested the relay and fuse by putting a paperclip on the thermostat temp sensor and turning the key to on… the fan came on.

At that point I decided it was probably my thermostat temp switch so I replaced that and the thermostat… ran the car for about 15 minutes… it got to normal operating temp… no fan.

im going to drive the car today around the block for a bit just to try and run it longer in case it didnt get warm enough… will see if that results in the fan coming on.

Wondering if anyone has any recommendations for me to troubleshoot next? Or can point me to an existing post that talks about the issue Im describing specifically.

Thanks for any help!

 

What brand thermostat did you buy and install ?

 

it is a Duralast thermostat… same brand for switch as well

 

It has been my experience that no brand thermostat works except a genuine Honda product. The typical causes are either the tail of the thermostat doesn't properly fit in the bypass pocket causing flow issues and/or there is no weep hole at the top of the thermostat plate to allow some hot water to fill the area where the fan switch is and activate the fan. Lastly, you must make sure that the cooling system is COMPLETELY filled with no air pockets trapped within the system.

 

thanks! I picked up the genuine thermostat and had some time to put it in tonight… I also opened the bleeder valve and let it bleed for a bit (it did sputter some and then smoothed out after about a minute, and then I closed it)… the system isnt taking any more fluid… still no fan… but im also not overheating? Do I need to drive for a long time to see if it comes on? Bummed it isnt coming on, but starting to question myself since the temp gauge inside always seems to indicate normal operating temp.

 

Cranking a car from a cold start (engine temp close to ambient) and letting it just sit and idle... normally takes 25 to 45 minutes (depending on the time of year/outside temp) for the coolant temp to get high enough to engage the cooling fan. With a factory fan switch, the coolant temp at the front of the thermostat will be nearly 200' F for the fan to come on. If you have unplugged the fan switch and jumped the two pins in the plug with a wire or paper clip and the fan comes on... and you replaced the fan switch with a brand new Genuine OEM Honda switch... plug it back in and don't worry about it. I have NEVER seen a bad one right out of the package.

 

Thanks JR! Ill give it a nice drive this weekend and see how it goes… appreciate your responses!