Chrysler Repair: A/C fan for 1997 Dodge Van, haynes manual, dodge van

Question
Wow, I wasn't expecting an answer that quickly. Thanks! The van does have a pressure sensor switch on the refrigerant line. The switch has 3 wires. I thought the switch turned on the fan and compressor if there was enough pressure in the line, but turned off the compressor and fan if there wasn't enough pressure. I assumed that since the compressor was working, the switch was working. I'm not sure which of the 3 wires to short to test the switch. Maybe I should just replace the switch?
-------------------------
Followup To
Question -
Roland: The fans cooling fans on my 97 dodge van don't come on when the AC is turned on. The fans come on when the engine temp rises so I know they work. Also, the A/C compressor comes on when I start the A/C, but no fans, until the car starts to overheat.
Answer -
Hi Tom,
That is a puzzling situation. I have to work with a Haynes '96-99 manual which shows a 'typical' wiring set up for the A/C and that there is only one feed to the powertrain controller from the A/C switch at the panel and so I would expect that the compressor clutch and the fans would both be activated (or if there were something wrong with that circuit that neither would be activated). The Haynes shows both the compressor and the fans to be controlled by the engine controller which implies that the same input would energize both relays.  In the earlier models ('93 for which I have a Chrysler shop manual) there was an extra fan grounding relay which appeared to be controlled by a switch near the compressor that sensed the pressure of the refrigerant in the A/C system and thus would energize the high speed fan whenever there was pressure developed in the system. But I don't see that relay or sensor in the Haynes manual. So I can't give you a certain answer for this problem. If you can find a Chrysler shop manual for '97 at a public library that may explain the system in detail. The Haynes is skimpy on this subject. You might see if there is a fan ground relay in the power distribution center, in which case there is an A/C pressure sensor in the refrigerant line near the compressor that activates it and that sensor or its wiring to the relay may be bad.
Roland  

Answer
Hi Tim,
You are correct about that switch. That is why I suspect it is not the problem because the compressor continues to operate and the A/C system is working properly. The other switch, shown in the '93 manual wiring diagram works to provide an alternative fan activation route via the grounding relay for the high speed fan and is said to be in the "front of the van". But I believe that relay was eliminated from the circuit, at least according to the Haynes generic diagram. By the way the '93 A/C circuits vary depending upon which engine, so that may be relevant as well. The pressure switch signal wire according to the Haynes is the dark blue, the black/light blue is the sensor ground, and the violet/ white is a 5V supply in case you wish to check that out on your van. But I would doubt that it is not working.
Roland