00 with 203k miles 5 speed SE...bought it 3 weeks ago and been driving it since,the only time it over heats is when AC is on and idling in traffic, when i pop hood radiator hose is FAT and full of pressure and water is overboiling and being pushed over into overflow reservoir. The driver side fan is only fan that comes on and its not going onto HIGH its blowing but not Fast like it should if it was overheating.


i changed thermostat when i bought it but it never fixed it,i been driving with heater on low and it dont over heat no more.


how do i test fans? and are they post to both turn on n have a hi and low like my 4th gen? i swapped relays around and no help.

 

Both fans should be on. Check for voltage at the harness under those conditions. If you have voltage then the fan motor is bad.

Check the coolant return hose at the bottom and make sure the top hose and bottom hose are similar in temperature. If the hose on the bottom is cold, then you could have a plugged radiator.

 

Upper and lower Hoses get super Hot.

 

Fan motor or harness problem.

 

Semi-short theory of operation for the radiator fans.

When you start the car and the engine is cold and the air conditioning is OFF, fans do not run. When the engine coolant temperature reaches 200 degrees, both fans run at low speed. When engine coolant temperature reaches 220 degrees, both fans run at high speed.

When you start the car cold and you turn the air conditioning ON, both fans immediately start running at low speed. When the engine coolant temperature reaches 200 degrees, both fans run at high speed.

Fuse G, labled RAD FAN 1, is used only by fan motor-1, driver's side of radiator.
Fuse H, labled RAD FAN 2, is used only by fan motor-2, passenger side of radiator.

There are 3 relays used to control the fans.
Fan relay-1 controls the low speed on both fans.
Fan relay-2 controls the high speed of Fan-1.
Fan relay-3 controls the high speed of Fan-2.

All 3 relays get 12 volts to its energizing coil from 15 amp fuse F20 when the ignition switch is in the ON or START positions. Current flows through the energizing coil when the ECU completes the path to ground.

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Both fans always run together, never one only. Start by wiggling the fan blades by hand. There should be absolutely no play or wiggle. The blades should spin with almost no resistance. If either of these 2 tests fail, the motor is bad and if it is still working, it won't be for much longer.

If the fuses are OK and the motor(s) don't run, check for voltage at the fan motor connector. Start the car and turn the a/c on. For the motor on the driver's side, check the white/red stripe wire. For the motor on the passenger side, check the green/red stripe wire.

 

Wow Thanks ALOT this is exactly the info i need Plus More! I will do the power test tommorow. Tonight i just sea foamed my car and out of the BLUE the driver fan that only runs on low when over heating went into HIGH mode right after i sea foamed that really weird but ill do those test first thing n morning Thanks for takin time to explain how they supposed to run!

 

I don't know where you live, but if it is in the northeast where the weather is a little chilly, there is a detail you need to be aware of.

If the outside temperature is below 35 degrees Fahrenheit, the a/c won't turn on. This is a precaution so that the evaporator coil doesn't freeze.

 

I had a radiator fan quit working, so I replaced the fan assembly. Even with only one fan working, my car never overheated with the a/c on, and this was during the peak Florida summer months.

 

I had a bad fan motor and I did see my coolant temp rise when idling or stuck in traffic.

 

I also got some temp rise, but it wasn't much. The OEM aluminum radiator does a good job, as long as it's free-flowing and not clogged up from lack of a proper flush.

 

Fan motor failure is a common 2K problem. Replace the entire fan assembly yourself for $100 and see if the problem is solved.