ENGINE TEMP GOES TO HOT. I APPLIED POWER DIRECTLY TO FAN FAN OPERATES.BUT WHEN THE ENGINE GETS ABOVE OPERATING TEMP THE FAN DOES NOT RUN.

Could be temperature sensor if car is not overheating.
make sure your coolant level is good.
Just to make sure you know this. The radiator fan is activated by the coolant temp in engine. The radiator fan can come on even if the car is turned off.
Something I would check first. Look at the radiator fans. If you have 2 one will come on and off with the A/C. The other will come on when the engine gets to operating temperature. As long as the engine temp is in normal range the engine fan should stay on. When temp seems to rise above normal make sure the fan is running.
I had a issue years ago where the fan relay would get very hot(hot compared to the other relays) and would open and the fan would go off. When the relay cooled down it would close and the fan would run again. I fixed by changing the relay.

Most engines today run very hot intentionally (an engine is a heat pump and is most efficient when the most heat is being made, but below the heat level that will cause it to self destruct) Many competent shops have a "heat gun" that can accurately determine if the engine is too hot, or normal. If a fan problem is detected, the system needs to be tested to determine if it is the fan motor, relay, sensor or wiring/computer that is causing it. Since your gauge reading appears normal, you may not have a real problem, aside from that you can't touch the engine when it's hot, but you don't do that much while driving!

Hi Bajil, Have a diagnostic scan carried out and have the coolant temperature sensor and relay inspected for correct operation. It sounds as if a cable has become disconnected or that the operating circuit has become defective. The cooling circuit operation is correct when the fan operates when the engine temperature raises a fraction above normal. The fan will run for a number of seconds and then switch off, thereby maintaining the 'normal' operating temperature. Regards John

On some Camrys the radiator fan is run by hydraulic pressure from the power steering pump. I think the sensor you mention is the engine coolant temperature sensor, which is in the circuit which operates the fan when the engine becomes hot. If this fails the engine will overheat, yes. The fan does not cool the hydraulic fluid from the pump.

If your power steering fluid gets low the same thing can happen, but you would notice immediately as the steering would become intermittently harder.

Fan does not necessarily get jammed when it fails.. Unplug the fan and hot wire it to the battery. If it comes on, it's good if not, change it. If it comes on when jumped, check the fan relay. Many jeeps have three fans. One that comes on with a/c, one that is operated by the temp control system and a mechanical one that comes on when the engine gets hot (has a heat sensitive lock up feature)
The automatic one operates as follows: temp sending unit sends signal to the computer which sends ground signal to the relay which then sends power to the fan. Likely that is the malfunctioning system you need to check. Some relays are in the power distribution center and sometimes the relay is tucked in front of the battery.

Possibles.
1. Failed Water Pump..... Separation of the Impeller and Drive shaft, or coolant leak from the Pump body gland, or associated hoses in the Cooling system
2. Clogged External Radiator Core..... This can be a common problem, dependant on geographic location. Dirt, Straw, etc, gets trapped in the core tubes reducing the Air flow.
3. Failed Electric fan Power supply. Check Main services Fuse box for blown fuses on the A/C fan and Main engine fan. Again lack of through air flow will cause overheating.
4. A Main Fuse Box services supply MAXI fuse has Blown.
5. The Temperature sensor that operates the Engine fans has failed. This unit completes the circuit to the relay in the Main Fuse Box that energises the fan motors.
6. Fill cooling system, leave pressure cap OFF, run engine and look for excessive air bubbles while air is purged out of the system. Keep topping up until coolant overflows, then run up to normal operating temperature, top up as required, and the fans should start up.

ALTERNATELY, AFTER TOPPING UP COOLANT AND WITH THE ENGINE RUNNING, set the controls to MAX A/c and Blowers on Full speed, after the A/C compressor has cycled for about 30 seconds, the A/c condenser fan should start up to cool down the Freon in the System and at the same time operates both fans. If this has no effect go back up the check list, and systematically eliminate each phase.
HOWEVER, if it is none of the above, then you may have originally "Cooked" the engine, and warped the "Head" or "Perforated the Head gasket.

Best of luck with your endevours,
Regards, DT.

When you mention the radiator having a hot upper in pipe and a cool bottom out pipe tells me that the coolant is not moving around the engine. This could be down to a water pump not working, blocked radiator, thermostat not opening. The bottom hose should be cooler than the top hose but once the engine is up to working temp which is around 85/90 degrees c for an audi the bottom still should be farly hot to touch. Hope this helps

Electric fan on radiator is goofing off. chk if it comes on at all but watching gauge and listening for fan start uo just above operating trmp. Fan helps cool under 35 mph. Forced air cools over 35 mph.

Here are the cooling system diagnostic steps...First does the cooling fan kick on (with engine hot)? If not, check the fuse, if good then check the thermoswitch in the radiator (it's about an inch and a half in diameter located on the lower part of the radiator with two wires ) by disconnecting the wires and touching them together (again, with engine hot...at least 190 degrees) if the fan comes on, you have a bad switch. If not connect a 10 gauge jumper wire from the battery to the fan itself (there are three terminals,,, one high, one low and ground). With power direct from the battery (and a ground wire, if necessary) fan should run... if not replace the fan assembly... if it does run then you have a bad cooling fan relay (under the dash, I believe). Hope this helps... ;-)

This is normal for a car that has an electric fan system for the cooling system. There is a sensor that operates based on engine temp. When you turn your vehicle off the coolant stops flowing and the water temp goes up in the engine block. The electric fan may run for approximately two or so minutes.