When you turn the A/C on does the elect. fan suppose to come on evenin cold weather and whitch temp. switch runs it?

fans only operate when the coolant temp exceeds the preset temp setting
the engine runs and warms the coolant and eventually the thermostat opens
coolant flows and in really cold weather the air around the radiator ( especially if moving) will keep the coolant sufficiently cool so that the fans will not activate
The fans may switch on if it is left idling for a period of time as there will be no air flow from a moving vehicle

most commonly resistor and wiring?

The fan only runs when the engine gets too hot. Not sure which switch it is.

that motor has the common intake manifold gasket problem

change the thermostat, sounds like it could stuck open and wont allow the engine reach operating temp, also test the constant control relay module located to the right of the battery as your facing the front of the car, also test coolant temp switch it might be defective and producing a high voltage that would cause the fans to constantly operate no matter the temp. Hope this helps

Carefully raise the engine RPM above 2000 and observe the Radiator hoses for collapse. Have your cap checked for holding pressure.

The electric fans usually are 2 speed units. Check with Autozone or Oreillys for the relays which switch to high speed. Some rely on a second temp sensor; you may have changed the dash gauge temp switch and not the fan speed temp switch.

Then if no success you need to get the Fan clutch checked with a timing light. The fan clutch is designed to lock at higher temps. It is suppose to slip in cold weather. A mechanic would take a timing light with a RPM scale and compare the crankshaft RPM with the fan RPM to see if the fan clutch is bad.

Radiator fan is supposed to start working after the temp reaches a certain limit. And it is supposed to run til the temp reaches a certain lower limit. So when you switch off the engine and walk off the fans must be running to cool the water to that lower limit. Unless you seen that it runs well past that and does not stop at all. Does it start running when you start the engine? And runs throughout the time the car is running, which it should not. The relay seems to be out. It is this relay that controls the running of the fan. or the temp gauge. If the temp gauge is giving wrong temp then the relay has to keep working. Please check both, the relay and before that the temp gauge.

sounds like the sensor is becoming questionable or a hi resistance ground in this part of the blower sensor circuit

Just fixed this problem. Replace the sensor or switch on the thermostat housing and viola!

hi the temp" sender "in this case is a thermostatic switch normaly with 2 connections put an ohm meter across the connections when engine is cold it will show nill or full scale leave meter connected run motor up untill it is hot meter needle should have moved 1 way or the other if it did not the relay is at fault chris merlinv12