Coolant fans run all the time, VW

[Holly Goodhead]

Coolant fans run all the time, VW

VW Golf TDI 07 plate,

This is in fact common to see, fans run all the time with key on, on running a scan test you may find no codes, but first check 01 engine and elecs:1 and the air con system, test the live data for the coolant temp is right for the temp of the engine.

Check the temp sensor in the bottom hose, grey plug, you can get at it by removing the air box.

If all is ok the fault may well be the fan it's self, the big one to the near/side.

This fan is more than just a fan, it has a module built in and it can fail, making the two fans run all the time

It's a new fan, no other fix

[Holly Goodhead]

[Minato]

The command circuit be inside the fan and it seems be locked always on.

Old cars use sometime an external power relay, but i think new cars use power Mosfet transistors. The main trouble is a power fan can be a very inductive load, so can make high surges when it is switch off brutally.

[Timbo]

Originally Posted by Minato

The command circuit be inside the fan and it seems be locked always on.

Old cars use sometime an external power relay, but i think new cars use power Mosfet transistors. The main trouble is a power fan can be a very inductive load, so can make high surges when it is switch off brutally.

Sure many ecu and control systems are close to or within the motors, sparks loads will in time take them out, idle control motors are one more thing that can and will take it's control circ: out
Timbo