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 ?

 

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

 

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.

 

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?

 

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.

 

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

 

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.