2007 4.7 commander radiator fan

My radiator fan will not come on with ACor run slow
Doesn't come on at startup like it used to

Any relays and location of them to check?
I have resistor on fan any way to check that?

I put power to fan direct from battery and it runs but not like it should at full power

I put volt meter form 2 prong plug to fan and it reads 18 volt then gets lower then zero. I did swap relays also
Am going to replace mechanical fan clutch (loose) and water pump
So while they're off I'll do electric fan.

Look in the electrical center under the hood. It should have a black cover on it and a diagram should be on the bottom of the cover.
Put your volt meter on battery with engine running it should be around 14 volt.
I can't understand where your getting 18 volt.
A resister should lower voltage. Check how many ohms across the resister.
http://www.ebay.com/ Search item 131221252134 Pictures notice 4 small and two large connections. Did you put battery voltage on two large connections?
The resister will drop voltage and slow down the motor. Look at the plug it appears you must have a high and low speed relay. You can move relays around if they are the same size and non essential. Then replace any bad relays. I would need a manual as this is a type I'm not familiar with.

So sorry I corrected statements
I ran power straight to fan took plug off.

http://www.Lunghd.com/Tech_Articles/Cooling/Electric_Fan_Diagnosis.htm
Thanks but I have a 2007 Commander XK with 4.7 you linked the 4.0.

I think they 4.7l radiator fan will be wired very close if not the same.