87 420SEL electric fan issues

[waybomb]

My aux fan runs full speed all the time.

Can somebody tell me which temperature sensor is the one controlling the electric fan on my 87 420sel? Is this a normally closed or normally open switch?

Also, which switch (location) in the ac system turns the fan on if high head pressure is present? Is this NO or NC?

Finally, Relay D is for the aux fan resistor. Where is this resistor, and how does it work?

Thanks in advance.