Radiator fan switch test and replace
 

This is about the radiator fan switch located right beside the thermostat ('99 4-cyl). I think mine's not working because the fans dont come on when the engine gets hot, which they used to before. I unplugged the connector on the switch and shorted the contacts, the fans came on so nothing else in the circuit is wrong.

I believe the temperature rating for the switch is 196-203°F.
Are there any aftermarket switches that close (switch on) at a lower temperature
like 170° or 160°F ?

Re: Radiator fan switch test and replace (AnAccordIsForever)
 

Use honda factory switch. I have a 98 lx 4-cly with 140k and still original switch working perfectly. Why has your gone bad?

Re: Radiator fan switch test and replace (Elvis1977)
 

I have no clue why it would go bad, out of all the things that could go bad by 77k miles. I tried checking resistance also, cold is open but engine hot still doesnt show some resistance.

After how long the engine has been running typically does the coolant temp reach 190-200°F ? I remember only once when I left it idle for a while (>5mins), the fans kicked in but went off in a matter of 3 or 4 seconds.

Re: Radiator fan switch test and replace (AnAccordIsForever)
 

On a hot day, they will kick on about 10 minutes of idling. On a cold day, probably longer. What does the temperature gauge say? Does the needle point in the red?

Re: Radiator fan switch test and replace (Elvis1977)
 

Temp gauge is showing fine - a little under halfway mark between C and H - which leads me to believe that the thermostat is working fine and the coolant is flowing as it should.

Re: Radiator fan switch test and replace (AnAccordIsForever)
 

The switch is probably ok also. Nothing to worry about.

Re: Radiator fan switch test and replace (AnAccordIsForever)
 

That isn't supposed to switch the fan on until the temperature gets hotter. Usually a little above 1/2 on the gauge.

It's just an SPST switch. It's supposed to measure open circuit until it switches ON. It's not a variable-resistance type of sensor. You can test it by putting it in a pot of water with a thermometer.

This time of year (in MN) you'll probably have a hard time getting your engine hot enough to switch it on.