I recently replaced my radiator, and now I have noticed I will overheat when idle for too long. I realized my cooling fans are not turning on. Fuses look ok.

Can somebody tell me what that thing is in the bottom of the radiator. Because when I UNHOOK it, the fans come ON...but when I plug it back in, the fans stay off! Is that the thermostat? Because when I did searches, it sounded to me like the thermostat was on the engine but maybe I"m confusing the issue. Thanks!

 

What engine, V6 or 4 cylinder and year.

when the engine overheats do the fans come on?

The item at the bottom of the radiator is the coolant temp sensor for the fans.

If the fans come on when you unhook it and stop when plugged back in, the system is working as designed. Depending on the year/model of car, the switch connection can open when coolant temps are 199-208F.

Note: the fans come on when the switch is open, not closed as one would assume.

The thermostat is on the engine. Depending on engine model can either be on the coolant intake or exit side of engine.

 

Hi Toyo.

1997 Camry 4 cylinder XLE.

The fans NEVER come on. In fact, I can't remember the last time they have come on LOL. Even with my coolant boiling over, the fans do not come on.

They DO come on when I turn the AC on, if I remember right.

I"m thinking I need that temperature sensor replaced perhaps? Just wanted to see if it was that, and not a thermostat.

 

I mean theoretically, that coolant temperature sensor should have an "on" and "off" state correct? So I assume it must be broken since it never allows the fan to come on even with boiling coolant?

I'll wait for your answer before purchasing a part, but I found one on eBay for 22.66 shipped.

 

Normal for fans to come on with AC.

Follow the lower radiator hose to engine. T-stat is in a housing the hose connects to on engine.

Fans should come on when engine is idling too long, stop and go traffic, etc. If never coming on then check the sensor switch at the bottom the radiator. Switch should activate fans long before the coolant boils.

 

I guess I will order a new sensor switch. I found two different ones on eBay, but the cheaper one (1st one) looks kinda different?

Toyota/Lexus COOLANT TEMPERATURE SENSOR Sending Gauge | eBay

DELPHI TS10198 Coolant Temperature Sensor | eBay