Once resistor is removed how is the unit tested
Car has ecc.
Thanx

 

measure the resistance. The way the ECC works is for fan speeds 1,2,3 the power flows through the resistor with different impedance values by pin. when fan is on high (4) the resistor is bypassed. So if your blower is running slowly on high, its not the resistor's fault and time to check the blower cage and motor for debris (particularly if you don't have a cabin air filter installed (this was an after market add for the 850s ) and you can try lubing up the bearings. If you have a missing speed or a speed that works part time, you likely have a bad resistor. If you are missing speeds 1,2,3 its possible you blew the resistor's thermal fuse - designed to keep it from overheating from too much current draw. It'd be a good idea to check the blower before replacing the resistor's thermal fuse (or the whole unit). If your blower is making noises etc, time to replace it - check out the Robert DIY video on youtube for replacing the blower/cage.

 

This wont work for ECC. ECC systems are variable fan speeds. You can only test on a non-ECC system. (thought I went over this already)

 

Situation was initially intermittent operation.
Working fine then not working for a period of time. this went on for quite a while. then finally no operation.
no noise or problems with fan while in operation
Unit just quit.
Checked fuses all okay
Possible relay?
if so which one is it
have replaced fuel pump relay as per Robert's vid
Thanx.