If radiator fan is not kicking back do i have to replace the thermostat

I dont think this is connected to the alternator, unless you have been removing wires or hit the thermostat switch in the radiator or hit the thermostat housing and the valve is blocked up. if its boiling up and the fan is not kicking in and the main pipe from the top is cold then the thermostat is not working, if all the pipes are hot and the fan is not turning on then its the thermo switch on the radiator or the motor has decided to go.

The catalytic converter probably has nothing to do with the problem. Either the replacement thermostat is bad, or the there's something plugging your cooling system. Have you tried a radiator flush?

• Sounds to me like your thermostat is stuck OPEN as opposed to stuck closed. When the thermostat is stuck closed, to much pressure builds. When the thermostat sticks open then pressure never builds. This is why the fan is not kicking on, no pressure and the car really never gets to a normal operating temperature either. If it was winter you would notice very little, if any, heat coming through the vents either.
• Replace the thermostat and you should be back to normal.

• Hope this helps and thank you for using FixYa.

Regards, Tony

Several things may be the culprit:

Fan relay - this tells the fan to turn on when the AC is turned on - $50 part DIY
Thermostat - should be in the front of the engine on top with hose running to it - $9 part DIY
Radiator Fan shot - u can replace the fan motor for about $100 DIY
Coolant temperature sensor - tells the fan to kick on when the coolant gets to a certain temp

While the engine is running and warmed up, lift the hood and listen or look to see if your radiator fan is running (the fan should kick on around 190-210degrees) if not, turn on the ac and and see if the fan starts running, if not, your fan motor is bad

Hope this helps

If you replaced the thermostat I would look next at the electric cooling fan thermostat.. Its likely located in the radiator itself and is in charge of turning on the electric fans.

To check. start the car and listen for the fan next to the radiator to kick on. It should start running before the car gets over heated.

Also when the temp gets really high is the radiator hot? if not then you still have a coolant flow problem. If the radiator IS hot then you have a problem with the coolant not getting cooled. Either an electric fan/thermostat of if you have an engine driven fan maybe its clutch is bad.

Most common overheating problems are: 1) incorrect coolant or degraded coolant mixture (check specific gravity), 2) bad thermostat (replacement it simple and part is cheap) , 3) bad water pump (will usually see a leak at pump or hear gurgling coming from heater core area when warming up engine) 4) bad radiator (will be leaking / steaming from radiator area) 5) cooling fan not coming on after engine has reached operating temperature). First, deternine the specific gravity of your coolant. You can buy a cheap tester for this, or some auto parts stores will check it for you. If your coolant looks discolored or rusty, a flush and coolant change would be first line of action. Second, determine if your cooling fan at radiator is coming on. Start engine and allow it to idle until you have reached operating temperature, about 3-10 minutes. With hood open, you can visually and audibly notice the fan kick on after that point within the next 10 minutes. If not, could be bad temperature sensor or fan relay. To test temp. sensor, remove wiring clip on the sensor usually located on or near thermostat housing (follow large hose from top of radiator to where it connects to engine, that is the thermostat housing). Using a multimeter set to OHMS @ 200 , should get a reading of about 81 ohms resistance. If bad, replace, test warm up procedure as before. If still not kicking on, better to take to a mechanic to check relay system if you are not very mechanically savy ;) If fan kicks on primary stage and engine overheats, replace thermostat. Do this by tracing to the housing, remove bolts on housing retainer to expose thermostat,replace, reseal with gasket and RTV sealant (use sparingly) or if o-ring type, no sealant used. Spring end toward engine block, then put housing back on tighten bolts a good hand tight, do not overtighten, as you can crack the aluminum housing. Use warm up procedure as before and check to see if still overheating. If so, could be clogged radiator. If you have leaks, trace to origin, that is most likely the cause. Let us know what you find.
Mike

not likely it is more than likely the waterpump, make sure the thermostat was not put in upside down. if fan is not kicking on it is a fuse or coolant switch for the fan

Sounds like a partially obstructed radiator, either external, leaves between a/c condenser and radiator, or internal...some cores plugged ...radiators are actually too small for engine in the first place, making them what I consider marginal even when new. A good clue to an internal blockage is if the radiator cannot be filled quickly...a really bad one requires coolant to be literally dribbled in when filling, but likely yours isnt that bad yet. Everything else you mentioned seems normal

check if the cooling fan cuts in if so see if the radiator is hot? If the rad is not hot probably needs a thermostat if it is hot could be water pump or head gasket

Radiator Fan Control Relay Switch. I bet your electric fan doesn't run?