Chrysler Repair: cooling fans, chrysler voyager, haynes manual

Question
hi i have a 1997 chrysler voyager. the temp gauge reach boiling point, a/c on and both cooling fans not coming on.i've tested temp switch,fuse,a/c relay, all seems to be fine.can you please tell me what the problem might be?

Answer
Hi Lee,
The circuit is very simple, according to the Haynes manual that I have. The power for the fans comes from fuse 4 in the power distribution center (40 amp, under the hood in the same box as the relay). Pull the relay and make sure that one socket is 12V all the time, if not, then there is something wrong with fuse 4 or the wiring in the pdc). Once you find the hot socket, jump a wire across from that socket to the one directly opposite, thus replicating the purpose of the relay. If the fans turn on, then that part is fine, if not, then the ground wire (black) at the fan disconnect plug is open or the fans are both bad. Check the black wire at the fan disconnect to make sure it is grounded somewhere near the fans, probably at the left side wall or the left headlamp module which is the usual ground point for many circuits. Then reconnect the fan plug and try it again. If you have a ground on the black and 12v jumped across the relay socket and still no action then check whether the dark green wire at the disconnect plug for the fan is getting the 12v that you jumped across the relay socket, if you do then the fans are bad or the dark green wire from the disconnect to the fans is open. If you don't then the dark green wire from the relay socket to the disconnect is open. So it you now can get the fans to work with a jumper across the relay socket, and still the fans don't work as they are supposed to (basically just start the van and turn on the a/c, the fans are supposed to come on regardless of the engine temp) then you have a problem with the relay control from the powertrain computer or the relay itself. You said that you checked the relay so I won't discuss that. The other two pins in the relay socket control the relay switch function. One of those should be grounded (the same black ground wire that you verified earlier grounds that pin when the fan disconnect is connected). So find that pin socket. The opposite pin socket is from the powertrain controller (light green/dark blue) and that pin is what is seeking a ground point in order to energize the relay. So that pin should have 0v or float when the engine is off. When you start the engine and turn on the a/c however that pin should show 12v or some other voltage so that current flows thru the relay coil and energizes the switch function. So check that it does get 12V or something like it when you start the engine and turn on the A/C. If you do, and the relay is known to be good then the fans should run. If you don't get the 12V then the wire from the controller to the relay is open or the controller itself is bad. I don't have the pin assignment for the light green/dark blue wire at the pcm. But let me know which engine and how many plugs are on the pcm and I might be able to tell you from another manual so that you can check that wire before trying a new controller.
Note that you can do this circuit testing without warming up the engine, the fans have to work with the a/c only too for them to work when the cooling system overheats and the temp sensor then turns on the fans thru the same control wire to the relay.
You will need a volt-ohmmeter or a 12v neon test light and continuity checker to verify all of the above.
Good luck and let me know if it still doesn't work. If I am maxed out send a comment as described and I will get back to you.

Roland