Chrysler Repair: 1995 Chrysler Town & Country van radiator fan, coolant temp, diagnostic capability

Question
The radiator fan on my wife's 1995 Chrysler Town & Country Van won't come on.  The dash temperature indicator seems to read the proper water temperature but when the temperature reaches very high levels we only get the idiot warning "Check gauges".  We recently had a problem with the wiring harness but that has been repaired.

Thank you,
LukeM

Answer
Hi Luke,
The fan system is fairly straightforward to diagnose. You will find a disconnect plug near the wire at the fan motor. If you jump a wire from the + post of the battery to the contact inside the disconnect that is connected to the dark green wire going to the motor you can test that the motor is good. (Only jump to the dark green as the black wire is grounded and so it if you jumped to the wrong pin you would have a direct short across the battery which is dangerous in that the current will be very high and likely to burn out the jumper or the black wire that carries the current to chassis ground and cause you a burn if you are holding the wire(s)). You may be able to assess the fan operation as well by turning on the defroster with the engine running, which starts the A/C which also asks for the fan to come "on".
If it seems that the fan is running o.k., then the next link in the chain is the fan relay which is located in the power distribution center under the hood also, in a rectangular box on the driver's side (I don't have the '95 diagrams but I believe that by mid 90's there was such a center for the larger fuses and relays). Look for another relay of the same ID # and try switching it out with the fan relay and see if that solves the problem. If not, then the coolant temp sensor or the engine controller may be the problem. The way to check those is to take advantage of the self diagnostic capability of the engine controller.
You will be able to do a self-diagnostic test that will help identify the reason because up thru the mid 90's the engine controller had a memory which stored fault observations as codes that the owner could readout without special instruments: Begin a readout as follows: Take your ignition key and turn the ignition switch "on-off-on-off-on" and leave it "on". Do this switching quickly so that no more than 5 seconds elapses. Then watch the 'check engine' light to begin to flash, pause, flash, pause, etc. Count the number of flashes before each pause and make a note of them in the order that they come. The last two flash groups will be 5 in each. Repeat the readout until you have the numbers accurately (the same result, two times in a row). Then pair the numbers two at a time in the order they came, to form two-digit numbers, for example the last number will be 55 which is the code for "end of readout". If one of the codes is 35 then there is a problem with the fan relay circuit which will require some analysis with a volt-ohmmeter. If you get a 22 code it means there is a problem with the coolant sensor not producing the correct resistance when the coolant gets hot and thus not causing the relay to energize and the fan to run.. If you have an ohmmeter you can check that out.
Without going into more of those details, why not try some of the tests I have listed and let me know what comes up with them and any readout results. We should be able to get this fan to run as it is supposed it. Also, when writing back tell me the engine type and size.
Roland