heated at higher speeds

[ricky]

On my drive home Friday, I was on a long stretch of road [50 miles]. Cruise was set at 79, A/C at 72. the temp gauge rose to the upper range [pointing at the 35mph mark instead of the 25 it usually sits at]. I turned off the A/C and it came down to normal and on the last 50 miles after. cruise at 64, it showed normal with the A/C on. A/C has plenty of freon [may have a touch too much] I am going to check today. Also plan on cleaning the radiator and A/C condensor. Any help on causes or cure will be appreciated. The radiator was full of fluid and has been flushed yearly. There were no other driveability problems as best I could tell. THANKS

 

[Mr Anonymous]

Check to make sure your fans are coming on. With the A/C compressor engaged (any climate control setting except off, floor, or vent) the fans should run on low speed constantly.

 

[SHOZ123]

The cooling fan motor is controlled during vehicle operation by the constant control relay module (CCRM) and powertrain control module (PCM), which will energize the cooling fan motors under the following conditions:

Cooling fan motors will run at low speed if:
engine temperature is higher than normal. Cooling fan motors start running at 102°C (216°F) and stops running at 100°C (212°F).

A/C is on and vehicle speed does not provide enough natural airflow. Cooling fan motors will stop running at speeds over 61 km/h (38 mph) if coolant temperature is below 100°C (212°F) and A/C head pressure is below 1.71 MPA (250 psi).

NOTE: Cooling fan motors will not cycle with the A/C clutch (2884). The cooling fan motors will come on when the A/C switch is turned ON.

Cooling fan motors will run at high speed if:
Engine temperature is higher than desirable and cooling fan motors have been operating at a low speed. Cooling fan motors start running at high speed when coolant temperature exceeds 109°C (228° F) and return to low speed when coolant temperature drops to 106°C (222°F).

Sounds to me like your radiator fins and condenser fins are full of fuzz. A common problem with all GEN3 Taurus and one not easily remedied. Go to http://v8sho.com/SHO/RadiatorCleaning.htm to see one way.