Cooling Fan Problem

[bosun99]

My 1992 Carina 2.0 (3S-FE) has started overheating due to the fan not coming on. Initially, I isolated the fault to the cooling fan temp (CFT) switch or thereabouts as when I fiddled with the connector, the fan ran for a short time. However, the fan remains off permanently except when I disconnect the CFT at which point the fan starts up. When I reconnect the plug then the fan stopts.

This really has me puzzled as the plug appears to be shorted when disconnected but not shorted when connected. I am guessing that this is something to do with the way the relay is wired. What is likely to be at fault, The CFT relay or the CFT switch or something else?

I recently had a new water radiator fitted and I believed they used the old CFT.

An ideas much appreciated.

[trev3635]

My 1992 Carina 2.0 (3S-FE) has started overheating due to the fan not coming on. Initially, I isolated the fault to the cooling fan temp (CFT) switch or thereabouts as when I fiddled with the connector, the fan ran for a short time. However, the fan remains off permanently except when I disconnect the CFT at which point the fan starts up. When I reconnect the plug then the fan stopts.

This really has me puzzled as the plug appears to be shorted when disconnected but not shorted when connected. I am guessing that this is something to do with the way the relay is wired. What is likely to be at fault, The CFT relay or the CFT switch or something else?

I recently had a new water radiator fitted and I believed they used the old CFT.

An ideas much appreciated.

Try your thermostat first, as far as i am aware when you unplug the switch you are actually connecting the circuit because you are taking the switch out of the equation, the switch is there to stop the fan constantly running. At least thats how i think it works

If the thermostat is not opening the sensor won't be sending a signal to operate the fan.

Anyway let us know how you fix it, good luck.

[bosun99]

My 1992 Carina 2.0 (3S-FE) has started overheating due to the fan not coming on. Initially, I isolated the fault ................................. .

Try your thermostat first, as far as i am aware when you unplug the switch you are actually connecting the circuit because you are taking the switch out of the equation, the switch is there to stop the fan constantly running. At least thats how i think it works

If the thermostat is not opening the sensor won't be sending a signal to operate the fan.

Anyway let us know how you fix it, good luck.

Thanks very much for that info. That explains why the fan comes on when I thought it worked the other way around. I ring round tomorrow to see if I can get one locally and will post on here how I did.

I wish I had seen this site before when I had probs. I am posting another item shortly on fixing the sun roof if I cannot find anything in the archives.

Thanks again. :D

[bosun99]

Thanks trev3635, I have sorted it now. Drained rad and took out temperature switch. Tested in boiling water with circuit tester attached. It worked ok (circuit opened when boiling point reached). Then did same test with switch reattached to plug and sensor end dipping in boiling water. A bit of a balancing act but sure enough, the fan switched on as the water reached boiling point. Refitted switch and refilled radiator and all now working. I can only assume there was something wrong with the connection i.e. a short in the plug which prevented the circuit opening and the fan being activated. Thanks again for the tip about the plug as the other sites said short the plug to switch on the fan (which was the opposite of course).

Thanks again. :) :) :)