My fan will not turn on i replaced the thermostat the relay and put new coolant in the radiator .the cars over heating and the fan still will not come on any ideas.

replace fan switch. depending what make vehicle, it could be located
on the side of radiator, on thermostat housing, on cylinder head.

REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP.IF CAR OVER HEATING WHILE IN MOTION.MORE LIKELY ITS THE THERMOSTAT,LOW COOLANT IN RADIATOR OR COOLANT SYSTEM,BAD WATER PUMP,WATER PUMP WEEP HOLE IS LEAKING, WATER PUMP NEEDS REPLACING.CHECK ENGINE OIL,IF OIL LOOKS LIKE MILK SHAKE YOU HAVE LEAKING HEAD GASKET.IF CAR IN PARK AND OVER HEATS WHILE IN A LONG TRAFFIC LINE OR.BANK DRIVE THROUGH COOLANT FAN NOT TURNING ON, BECAUSE THE ENGINE COOLANT TEMPERATURE SENSOR FAULTY.CODE SCAN CAR FOR FAULTY COOLANT FAN RELAY OR FAULTY PCM. CHECK COOLANT FAN FUSE, AND HOT WIRE THE COOLANT FAN TO MAKE SURE ITS WORKING.IF COOLANT FAN DONT WORK WHEN HOT WIRED. COOLANT FAN NEEDS REPLACING. REPLACE BOTH RADIATOR HOSES, REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP.BUY NEW COOLANT ADD 50/50 WATER AND COOLANT.IF ENGINE OIL HAS ANTIFREEZE IN IT.REPLACE ENGINE OIL AND OIL FILTER TO KEEP FROM LOCKING UP THE ENGINE.GET CAR FIX.DONT KEEP DRIVING IF IT KEEP OVER HEATING,ENGINE DAMAGE WILL OCCUR.I HOPE INFORMATION I GAVE YOU WILL FIX PROBLEM.PROBLEM COULD BE LEAKING RADIATOR HOSES BUT CHANGE THERMOSTAT THATS FIRST THING I WOULD CHANGE BECAUSE IF IT CLOSED, ENGINE WILL OVER HEAT AND CRACK CYLINDER HEAD OR CRACK PISTON, COOLANT NEED TO CIRCULATE THROUGH THE ENGINE TO TAKE AWAY THE HEAT FROM ENGINE.

Some cars are designed to have the fan run for a few minutes after you turn the car off. But if doesn't stop until the battery drains, then it might be a faulty switch or temperature sensor.

Or, if the fan stays running when the engine and radiator are cool you have a very cheap problem: The fan thermostat is stuck closed. A new thermostat will fix the problem--the hardest part of replacing it is finding it. Follow the wires from the fan to the switch--it is usually on the bottom tank of the radiator. Drain the radiator first and save the coolant to put back in after you replace the thermostat. NEVER OPEN A HOT RADIATOR.

If that wasn't it then check the following:

• Check to see that your coolant level is correct. Top up as necessary.
  
• Lay your hand on the radiator (with the engine off) and feel if it is as hot at the top as it is at the bottom. If not, your radiator may be clogged and need flushed or replaced. (Flushing is cheap. Replacing the radiator isn't)
  
• Do you get heat from the heater? Leave it turned on high and see if your fan stays running the next time. If it takes care of the problem that could mean you have a kinked radiator hose.

Hope this helped (remember comment and rated this).

CHECK COOLANT LEVEL IN RADIATOR. BUT WAIT UNTIL THE ENGINE COOL DOWN. CHECK WATER PUMP.IF YOU SEE COOLANT LEAKING FROM WEEP HOLE REPLACE WATER PUMP. REPLACE THERMOSTAT AND RADIATOR PRESSURE CAP WHEN CAR OVERHEATING IF CAR AT A STANDSTILL IN LONG TRAFFIC LINE OR MOVING SLOWLY.COOLANT TEMPERATURE SENSOR FAULTY.NOT TURNING ON COOLANT FAN.CHECK COOLANT FAN FUSE AND RELAY.IF ALL IS GOOD.HOTWIRE COOLANT FAN.IF COOLANT FAN DONT COME ON FAN MOTOR FAULTY.IF FAN COMES ON CHECK ELECTRICAL WIRE CONNECTOR FOR DAMAGE WIRES.

yes the head gaskets leaking on modern aluminum head engines is all to common. never overheat them, if they start to get hot shut it down and find out why, it can of course be the fans and plugged radiators or faulty thermostats but sounds like in your case the head gasket is leaking and combustion gas is entering the cooling system and this causes an overheat

check the radiator coolant fan,or the R C fan relay. If radiator coolant fan went out your car will over heat when idle .

hi
1st u have to replace condenser fan and radiator assy , it will solve your problem , cause due to no coolant radiator fan is not working and cause of engine overheating a/c system got trip . replace both condenser fan and radiator and put new coolant. thanks.

The problem of over-heating could be due to one or all of these defective parts:
(i) thermostat
(ii) radiator
(iii) fan relay
(iv) fan switch
(v) water temperature sensor.
In your case, I suspect that your radiator probably is clogged, so needing replacement.

To Replace the radiator:
a. allow the engine to cool.
b. place a suitable container under the radiator, and drain it out by turning backward the wing-nut under it.
c. open the radiator cap to allow atmospheric air to further push down the coolant.
d. with a piece of pliers, depress the top clamp holding the radiator hose. Do the same for the lower radiator hose.
e. remove from the bottom of the radiator and plug wth suitable bolts, the two transmission fluid rubber lines.
f. with a 10-mm socket and wrench remove the two bolts holding the radiator to the front frame.
g. depress the electrical plug at the bottom of the radiator. Remove its thermo switch at the bottom left hand side of the radiator. (replace with new if changing to new radiator) Also notice two rubber cups at bottom of radiator.
i, installation of the new radiator is reverse of removal. Refill radiator with new coolant.

To replace thermostat:
a. disconnect the negative terminal of the battery.
b. drain the coolant into a container, as
explanied above.
c. remove the upper radiator hose from the thermostat housing on the engine block.
d. remove the two bolts from the thermostat housing. Please note the way it was bolted to the engine. Clean its housing and seating areas.
e. fit a new o-ring to the thermostat, and replace with a new thermostat.
f. tighten its bolts to 14-12-foot pounds.
g. Replace the top and bottom hoses back.
i. refill with new coolant.

To replace the fan relays:
a. open the hood.
b. disconnect the negative battery terminal.
c. locate the meduim-size black plastic box on the driver's side fender. This is where the fan relays are. Look inside the cover of the medium-size plastic box to see the fan relay positions.
d. gently and firmly pull out each fan relay. Replace with new ones as needed.

To replace the water temperature sensor:
a. this is bolted to the top of thermostat housing.
b. unplug it from it location.
c. use a 14-mm deep socket to remove the temperature sensor. Replacement is reverse of removal.

You may either have a bad thermostat or a bad fan relay. If the fan is not turning on at all then the relay is bad. If there is not any heat coming through the heater then your heater core is plugged. That would also cause an overheating problem as well. To rule out a bad relay check to see if you are getting 12 volts at the fan connection. If not change relay.

Thermostat, coolant sensor, fan relay etc. First check the coolant level, check for leaks. Check if the fans are on when the engine is hot, about to over heat. If equipped with two fans they both should be on. If its all good have the system flushed and a new thermostat installed. If you want to change the thermostat yourself follow the big hoses that are attached to the radiator. Look at each where they attach to the engine. It should be apparent where the thermostat is at the end of the hose. After replacing the thermostat if you don't top off the coolant and there is air in the system the car will over-heat with the new thermostat. Some times radiators have air bleed valves on top. If not then jack up the car a little. Jack it up in the side the radiator cap is at so the air can work its way out. To fill it add coolant when the car is cold, off, and jacked up. Leave the cap off and start the car this is so the thermostat opens and the coolant flows. Continue to add coolant until it over-flows close or put the cap on. Put coolant in the over flow reservoir fill it to the low level. If the radiator has the air valve you don't need to jack the car. If you did it right the car should not over heat and the heater should be working.