Radiator fan keeps coming on at idle and when operating vehicle when Heater is turned on .When open the hood you see A/c unit alternator trying to kick on spins and Fan go on at same time together .When Heat or a/c turned off they both stop and do not go on again as frequently . What could be the issue with this why Fan constantly goes on mostly when car is at a stop .

You likely have air trapped in the system. Trapped air keeps the heat sensing elements of the thermostat and sensor from functioning properly.
Easiest remedy is to either 1) jack up the front of the vehicle, (support the car with jack stands), when the engine is cold and with the heater set to high heat, disconnect the upper radiator hose and pour 50/50 antifreeze mixture into the upper radiator hose until antifreeze begins to come out of the radiator. Reconnect the hose and top off the coolant reservoir to the proper level for your vehicle. Start the vehicle and let it come to operating temperature. The vehicle may or may not have an air bleed located near the radiator cap, if it does, carefully loosen the bleed until all air escapes and antifreeze if present. If there is no air bleed. Once the vehicle has reached operating temperature (the lower radiator hose is hot to the touch, meaning the thermostat is open) shut the vehicle off and let it cool. Then open the radiator cap, releasing any pressure, add more antifreeze, and restart the vehicle. This should remove any entrapped air. Or 2) The alternative is to have the vehicle parked on a steep hill with the radiator at the up hill side and do the above process to remove the trapped air. Always block the rear wheels for safety.

Turn vehicle off. Allow to cool. Raise hood.
Try to see if the fans spin freely by hand. If not, replace. If they do spin, proceed to next step.
Next step-
Check coolant level, add if needed. Remember-radiator must be cool before opening cap. Make sure radiator cap is secure and tight if coolant was added.
Start vehicle. Observe coolant gauge as vehicle warms. Fans should come on when temp gauge reads halfway between c and h.
If fans do not come on see if they come on when you turn on ac or heat. If doing this makes them come on, suspect faulty cooling fan sensor switch. If they don't come on replace cooling fan sensor switch and fan relay.

Hello,
Here's something that's a very common cause of overheating, and it's easy to check.

How to test the thermostat in most vehicles;
Make sure the heater is off, start the engine and let it run for 6 to 8 minutes, ( this will allow the
engine to reach, " normal operating temperature "), from the inside of the vehicle turn the heater
temperature on high and turn the fan speed on high.
1. Listen very closely for a click sound from the engine, ( most thermostats make a click when
they open )
2. Watch your temperature guage, it should begin to lower as the coolant starts to circulate.
3. Usually within a few minutes the radiator fan will kick.


What the thermostat does;
It seperates your coolant into two parts. The first part is in your engine, the second part is in your
radiator and the coolant reservior. When the coolant in the engine reaches the temperature rating
on the thermostat the thermostat opens to allow the two parts of coolant to change places. Now
the cooled coolant in the radiator and reservior flows into the engine while the heated coolant flows
from the engine into the radiator and reservior to be air cooled by the radiator fan.

I really hope this helps you.
Donnie

the heater core for this vehicles located behind the glove box on passenger side.in order to remove it,you will need to be mechanically inclined.are you?do you have the tools to do so?8mm sockets and ratchet? you will need patience! if not,i recommend you ask your mechanic to replace it. but 1st i will ask these questions. is it the heater core? is fluid leaking onto the passenger side floorboard? that's one sign of a bad heater core. no heat? have you checked the fluid level in your radiator? does your cooling fan come on when the engine's at operating temperature? if not, then it may be a bad temperature sensor at the radiator. it may also be a bad fan relay in the main fuse box under the hood in the main fuse box[black box w/lid under the hood.lift the cover off of it and under the lid,it tells you fuse and the relay locations.if you turn your a/c on and the fan comes on,and does'nt come on when the engine gets hot,the fan sensor may be bad.the fan sensor that tells the fan to come on when the engines running hot. thank you,for choosing fixya,com!

mist likely you had the oil changed recently and they knocked off the wire to the sending unit that tells the fan when to come on - the fan only comes on all the time - -when the AC is on or as you state the defrost is on . I hope you have a regular mechanic as he will be a hands on friend if you ask him.

The radiator fan in the 92-95 models of V-6 Toyota and Lexus vehicles is a weird design. The fan is not electric but runs off the power steering pump. The power steering pump moves fluid through hoses to the radiator fan, thereby creating its rotation. A sensor monitors coolant temperature and signals a solenoid on the power steering pump when more or less cooling is needed. The power steering pump then speeds up or slows down to provide more or less fan speed.

This system seems to work pretty well. However, there is a connector that goes to the power steering pump that is critical to proper operation. In engine work this connector often gets overlooked when reassembly is done. This results in the fan running at constant speed and not increasing rotation when more cooling is needed. This becomes a problem primarily when the car is idling or moving at a slow speed.

If your car is not overheating in these situations, the fan is probably operating okay.

thats your main radiator fan, meaning if it don't come on then vehicle will get hot. check the fan for operation by letting the vehicle idle for a while, keep check the temp gauge and what for the fan to come on at the half way point.

First when vehicle is cold like in the morning check and make sure that the vehicle has enough coolant/ antifreeze in radiator and reservoir. If coolant is need use a 50/50 mixture of water and antifreeze. You will need some time to do this let car run at idle until the temp guage is in the middle NOT+ normal operating temperature. At this point if the thermostat should be in the open position. Let vehicle run and check to make sure that radiator fan comes on. This should come on when guage is about midway/half way. If temperature rises above half going to h/hot and fan doesn't come on, you either have a BAD FAN BAD FAN SWITCH BAD FAN RELAY OR BLOWN FAN SWITCH FUSE. You will need to check all of the following I will help if its needed. If fan comes on and doesn't go off and vehicle continues to get hot even with fan running. Feel radiator hoses and see if the lower radiator hose is cool/cold. If it is you have thermostat that stuck closed. Replace thermostat and fix problem. If all the above is good and vehicle continues to over heat. THE BAD NEW IS THAT YOU MAY HAVE A BLOWN HEAD GASKET /CRACKED HEAD /BROKEN WATER JACKET. Basically you will need a HEAD JOB at least a head gasket. ONe tell tail sign of this is oil looking like milkshake/chocolate milk-a creamish while residue in oil or antifreeze. Contact if you need hel0p. Good Luck and thanks for using FIX YA

it seems you have to seperate issues here. fiirst let's start withtthe over heating. you stated that you have replaced the pump,thermosta,fan,clutch,all the hoses, and core. now my question to you is did you route the belt so it's circulating like it should? is it steaming out from under the hood? to be quite honest the vehicle should not even be close to overheating after driving only 3 miles. there is a possibilty that you have a bad sending unit for the temp if it is not steaming out from under the hood. your upper radiator hose is hot this tells you that the thermostat is operating as it should. the fan should be turning clock wise as you are looking at it from the front of the vehicle.when you fill the system with coolant make sure that you have the heater on high and to the hot setting. check to make open sure you have plenty of coolant and that the radiator is free of dirt and bugs.. now as far as not having anyheat in the vehicle check the fuse for your climate control. look under the dash and make sure you hooked all the cables for your fresh air door and blend door. when you changed the core did you connect the hoses in the right place?after you have checked all the hoses and the coolant is as full as can be and the heat is turned on to max ,keep the radiator cap off and start the vehicle wait for it to get hot check the upper radiator hose to see when the thermo stat opens you should see that the coolant should go down in the radaitor. do these things and check back with me on the results...please rate this help...thanks