air con fan

[pgrem]

hi all,is the aircon fan supposed to click in when the car gets hot,someone mentioned earlier in my troublsome saga that they thought the electric fan on the aircon radiator also worked at a certain temperature as a cooling fan for the engine radiator.ive just noticed mine doesnt work at all and was hoping it could be a large part of my problem,i also note that theres a fuse marked radiator fan on the fusebox under the bonnet,which couldnt be for the viscous fan??cheers pete

 

[zippy656]

a fuse marked radiator fan on the fusebox under the bonnet,which couldnt be for the viscous fan??cheers pete

the viscous fan is just that, viscous. not electric so no fuse needed

 

[Timbo_1975]

The electric fan infront of the rad only runs when the a/c compressor clutch is engaged.

 

[lacroupade]

The electric fan infront of the rad only runs when the a/c compressor clutch is engaged.

which is a roundabout way of saying if yer aircon isn't switched on yer aircon fan isn't gonna be running? :thumbs

 

[Timbo_1975]

Not really no.

If your a/c is turned on, but the temp sensor is satisfied so releases the comp clutch, then the aux fan will also stop.

 

[lacroupade]

Not really no.

If your a/c is turned on, but the temp sensor is satisfied so releases the comp clutch, then the aux fan will also stop.

its a case of 2+2=4 LOL. My statement is accurate (no aircon on, no fan operating) and so is yours (aircon might be on but fan can still be off)..

damn...stalemate.

Still, either way for the OP it means the aircon fan will only be able to operate (subject to temp sensor) if the aircon is on:thumb2

 

[kbekl]

could always attach a switch to the fan and battery so operates from that

 

[lacroupade]

could always attach a switch to the fan and battery so operates from that

but its only gonna cool the aircon radiator surely?

his problem is much more fundamental than adding extra cooling.....needs to fix the root cause before its too late and he gets added to the 'cracked head' list:augie

Timbo can help but needs the info he's asked for....

 

[kbekl]

but its only gonna cool the aircon radiator surely?

his problem is much more fundamental than adding extra cooling.....needs to fix the root cause before its too late and he gets added to the 'cracked head' list:augie

Timbo can help but needs the info he's asked for....

no idea mate never had ac on mine

i would always advise the fixing of cooling and admit to not read the first post but the last group :augie

 

[lacroupade]

no idea mate never had ac on mine

i would always advise the fixing of cooling and admit to not read the first post but the last group :augie

and you think I don't do that LMAO!:thumb2

 

[Timbo_1975]

The long and short of it is that, a stock Terrano / Mistral with standard fuelling will keep cool no problem no matter what you do with it assuming the cooling system is in half decent order.

 

[solarman216]

Even in cold weather if you put your heater to cool and the fan on and select AC then look at the AC compressor belt pulley if the plate at the front is not turning then it is probably out of gas, all AC systems have a pressure switch that disables the AC if no gas in order to protect the compressor, and yes if the AC is on the air will go through the engine rad as well and can be a useful method of cooling the motor in stationary traffic, but not for other problems, Rick

 

[Timbo_1975]

Boring Info

AC temp sensor is in the heater plenum and hysteresis is roughly between 4 & 7 deg C on the terrano.

Dual pressures switch inhibits the compressor AND fan on both Low and High pressure.

Its worth noting that on the TDI the ecu has the final say-so to let the compressor run and also idles up abit. It also cuts the a/c under full throttle and when coolant temp is very high.

Circuit is:

B+ to Fan speed control switch -> ac switch -> temp sensor -> ECU.

ECU switched ground -> HP & LP cut outs -> relay.

Relay - comp clutch & aux fan.