Engine cooling problem

[aldwinenriquez]

Mine is a Toyota Corolla XL 90.Problem is excessive overheating when not using an aircon.(bizaare).It seems that the engine fan is not blowing automatically which causes overheating.
Because when the aircon is ON the fan is also blowing cooling the engine.But if Im not using the aircon,and the temperature goes above the tolerable temp,the fan is still not blowing up.

I speculate the problem might be from the thermostat sensor,but im not sure coz sometimes its blowing but only for a couple of seconds.

Again, no problem when the fan is ON (triggered by aircon).

Any ideas?

Aldwin

[REN69]

You might just need a new thermostat.. start with that, if the problem comes back then it could be the temperature sensor, which is located just near the housing where the thermostat goes(it has an electrical plug going into it). It could also mean your coolant is too old and has lost its cooling power.

[aldwinenriquez]

thanks,il try that one.

[fredk]

fan temp sensor

[karazy]

The thermostat doesn't control the fan. It will probably be the sensor or a relay.

[aldwinenriquez]

Maybe you're right about the relay coz when Im twiddling the relay sometimes the fan gets on but Im still confuse.I might sound demanding but could you tell me something about how are thermostat(not sure about this one),temperature sensor and relay work together to turn the fan on?

[karazy]

As in previous post, thermostat doesn't control fan. It controls coolant circulation. The sensor powers the relay, when the temp is in the correct zone. The relay allows power to the fan motor.

[aldwinenriquez]

thanks karazy