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Dodge Caravan Cooling Fan Operation

Q. Hi, I sent you the email regarding the A/C on this 1990 Dodge Caravan. It has the 3.3 liter V-6 in it and besides the A/C I am having a different problem with it. The Temp gauge is not working it stays on "C". I changed out the temperature sensor and it still doesn't work. It also seems like the radiators electric fan does not come on often enough. The radiator gets hotter than I think would be normal.

Dodge Caravan Cooling Fan Operation

Is there a way to test the fluid temperature and what temperature should it not exceed. For now so it can be driven. I have bypassed the relay with a toggle switch so I can turn the fan on and leave it on. I have also replaced the relay and that did not make any difference.


A. Fan control is accomplished in two ways. The fan always runs when the air conditioning compressor clutch is engaged. In addition to this control, the fan is turned on by the temperature of the coolant which is sensed by the coolant temperature sensor which sends the message to the on-board computer. The computer turns on the fan through the fan relay.

Switching through the on-board computer provides fan control for the following conditions.

  1. The fan will not run during cranking until the engine starts no matter what the coolant temperature is.
  2. Fan will always run when the air conditioning clutch is engaged.
  3. On non-air conditioned vehicles or with air conditioning off the fan will run at vehicle speeds above about 40 mph only if coolant temperature reaches 230°F and will turn off when the temperature drops to 220°F. At speeds below 40 mph the fan switches on at 210°F and off at 200°F.
  4. There also is included a method to help prevent "steaming" (water vapor evaporated by hot water circulating through the radiator evaporating moisture on the outside of the radiator and when there is no ram air to blow it under the vehicle) the fan will run only below 60°F ambient, from 100°F 195°F coolant temperature only at idle, and zero vehicle speed and then only for three minutes.

You can check the coolant temperature with a thermometer inserted into the radiator.

Additional Information provided courtesy of ALLDATA

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