Dodge Repair/Radiator cooling fans not working:'02 minivan
QUESTION: On a 2002 Dodge Grand Caravan with 3.3L engine with 76,000 miles, the radiator cooling fans stop working. Things that I have checked/done: tested the fans and they are ok; the fuses are good; replaced the cooling fans switch, the relay, and the thermostat. I turned on the A/C and the fans came on once only (the A/C blows simi warm air. What else should I be checking? If this is a wiring issue, how do I go about testing it?
ANSWER: Hi Carm,
It is not clear to me what you mean by the "cooling fans switch". I don't believe there is such a switch as the fan relay is controlled by the powertrain control module which activates the relay when it receives a temperature 'message' from the sensor near the thermostat housing OR from your activating the AC choice on the HVAC control panel to do so. HOWEVER, if the refrigerant level is below the minimum acceptable for the system to operate, then neither the AC compressor, NOR the radiator fans will run (perhaps except very briefly) until you add some refrigerant to the system.
When you activate the AC do the fans simply run for a short time and then cut off?
What is showing on the temp gauge of the vehicle as you drive (without the AC running)? Does the gauge go above 1/2 scale with no fan actuation?
The fans should come on when the coolant reaches about 200F. About the only intermittent explanation is that fuse 27 may have a subtle crack in its internal wire which 'opens' when it heats up.
Other than shaking the wiring harness to the fans for a possible flakey connection, I think we have to consider whether there might be air in the thermostat housing which is not allowing the coolant temp sensor to accurately assess the coolant temperature.
Thanks for the rating and nomination.
---------- FOLLOW-UP ----------
QUESTION: Roland - Thanks for the quick respond.
Sorry about that - I meant that I replaced the temperature sensor "switch" by the cooling returning hose on top of the engine. Since I first notice that the fans were not operating, the fans turned only once after I turned the A/C on. I turned the A/C on/off many times but the fans would not turn on. When I drive with A/C off the gauge goes almost to the midpoint. I also interchanged the 40A fuse.
If the compressor is not being activated when you request AC, then that would also explain why the fans won't come on immediately. So that again suggests the refrigerant level needs replenishment.
Then fans will not always come at almost half point, but should come on when the gauge gets to 3/4 of full scale most certainly, regardless of the AC refrigerant function issue.
Thanks for the rating and nomination which you can do both again if you would be so kind.