Radiator Cooling fan question

[zero18]

02 Lincoln LS (V6) 140K Miles

when I turn on the AC the fan comes on in about 10 seconds but it comes on full speed and never slows down.
If I turn off the car, turn off AC, start car, fan is normal until AC is turned on then back to full speed.
checked Freon @ 35PSI @ 70 Degrees.

any suggestions??
Thanks in advance!

 

[joegr]

...any suggestions??
Thanks in advance!

Works as designed.
(Note that if you wait long enough, the fan speed will come back down several minutes after turning the AC off, if the engine is not too hot. Also note, it is not a full speed. Unless you've had the engine start to overheat, you've never experienced full fan speed.)

 

[SoulSoak]

Yeah, Joe ain't kidding. With your fan on full speed it sounds like an airlplane turbine.

 

[zero18]

that how it sounds...
but to update, it seems like it doesn't happen below 70 degress.
once outside temp is around 73 degress plus it happens. I have had the car since 03 and it never does that.
I have had the radiator replaced about 2 months ago.

 

[joegr]

Degas bottle? Radiator hoses?

 

[zero18]

Degas bottle? Radiator hoses?

car runs at correct temp..

fan goes fast about 30 seconds after starting up cold

 

[joegr]

car runs at correct temp...

How have you verified this? What is the actual temperature?

 

[zero18]

How have you verified this? What is the actual temperature?

I was going by the gauge, but it cant be over heating within 30 seconds of a cold startup

 

[joegr]

I was going by the gauge, but it cant be over heating within 30 seconds of a cold startup

True enough. Where is the gauge 30 seconds after startup? Is the climate control on? (Note that the PCM reads the high side pressure, not the low side pressure.)
A good OBDII scan tool would let you see what temperatures the PCM is reading.

 

[zero18]

True enough. Where is the gauge 30 seconds after startup? Is the climate control on? (Note that the PCM reads the high side pressure, not the low side pressure.)
A good OBDII scan tool would let you see what temperatures the PCM is reading.

gauge not moved in 30 seconds.
if ac is on.. fan goes to high - if ac is off.. all is normal

 

[joegr]

gauge not moved in 30 seconds.
if ac is on.. fan goes to high - if ac is off.. all is normal

Maybe you should check the AC high-side pressure.

 

[zero18]

Maybe you should check the AC high-side pressure.

yeah, I checked that when I checked the low side..

kinda out of ideas

 

[joegr]

...kinda out of ideas

Well...

...A good OBDII scan tool would let you see what temperatures the PCM is reading.