hi, i have an octavia mk2 140bhp that currently has an overheating issue, now weve hot weather up north and the temp gauge can sit at the 90 deg. mark no bother but all of a sudden it will creep up to the red, the thermostat is working perfect but the fans for the radiator cooling arent coming on although we`ve plugged them direct to the battery and they work fine. im looking to find out where the relay or the heating control unit or temperature switch may be located as there`s nothing in the fuse boxes or any control switches near the radiators. any help would be appreciated. colin.

Are you overheating when the car is moving or does it drop back to 90?

Might be better off asking in the mk2 Octy group rather than the mk1 area.

Could be a coolant temp sensor fault.

its an intermitent over heating issue, the car could be running for about a week no bother then all of a sudden the temp gauge will increase. we own a taxi firm up here but this fault goes beyond my mechanical abilities, the car is on the road 7 days a week, and would be handy to know where the cooling relays are located for the fans or where the control module may be located as all ive found are the two cooling fan swithche and they are working perfect.

Please answer post #2.

If you have aircon, do both fans run when you turn it on?

Please answer post #2.

If you have aircon, do both fans run when you turn it on?

sorry, still overheats when on the move and no fan movement with aircon on. aircon is working though.

Usually, you don't need the fan except when your stationary or in slow moving traffic or you have the aircon on. Just the air hitting the radiator is more than enough. If the water in the radiator isn't hot enough, the fan won't come on. My guess is you have a flow problem. Maybe a sticking thermostat of a failing coolant pump.

To check the fan, disconnect the connector from the temperature switch. Bridge 1 & 2 to check slow speed. Bridge 1 & 3 to check full speed. If you get nothing, the check fuse 3 on the front side of the eBox.

Usually, you don't need the fan except when your stationary or in slow moving traffic or you have the aircon on. Just the air hitting the radiator is more than enough. If the water in the radiator isn't hot enough, the fan won't come on. My guess is you have a flow problem. Maybe a sticking thermostat of a failing coolant pump.

To check the fan, disconnect the connector from the temperature switch. Bridge 1 & 2 to check slow speed. Bridge 1 & 3 to check full speed. If you get nothing, the check fuse 3 on the front side of the eBox.

temp is definately above 90 usually shows 3/4 or more on gauge smell of cooking rubber and bottom rad hose split to the hessian due to excessive heat, fans are working when linked direct to battery. surely fans should come on at this temp. connector plug to fans tested and circuit to fans is complete. is there a relay or control unit that instructs the fans that could be faulty?

temp is definately above 90 usually shows 3/4 or more on gauge smell of cooking rubber and bottom rad hose split to the hessian due to excessive heat, fans are working when linked direct to battery. surely fans should come on at this temp. connector plug to fans tested and circuit to fans is complete. is there a relay or control unit that instructs the fans that could be faulty?

any idea where the temp switch is located,can't see anything on the rad,sorry thisis a mk 11 and i should be on the mk 11 forum, apologies!

temp is definately above 90 usually shows 3/4 or more on gauge smell of cooking rubber and bottom rad hose split to the hessian due to excessive heat, fans are working when linked direct to battery. surely fans should come on at this temp. connector plug to fans tested and circuit to fans is complete. is there a relay or control unit that instructs the fans that could be faulty?

sorry i see where you're coming from now that i've re-read your comments.so if the engine coolant is too hot and not getting through the rad the sensor that instructs the fans must be on the rad somewhere. sorry if i'm hard work just tell me i only have a basic knowledge of cars. p.s. cant find any sensor unit on the rad.

sorry i see where you're coming from now that i've re-read your comments.so if the engine coolant is too hot and not getting through the rad the sensor that instructs the fans must be on the rad somewhere. sorry if i'm hard work just tell me i only have a basic knowledge of cars. p.s. cant find any sensor unit on the rad.

Yes. The coolant in the rad isn't hot enough to switch on the fan.

The only connection to the radiator/shroud/fan is a 4 pin connector. Between it and the fan is 3 pin connector which connects to the rad switch.