Contour Enthusiasts Group Archives Forums General Troubleshooting Air conditioning blows freezing cold one minute, hot the next....

Ahem,

Passenger cars are driven at SLOW speeds compared to NASCAR STOCK CARS.

The Body of a NASCAR STOCK CAR is designed so that the window areas are RECESSED,
and the external airflow is not interrupted when flowing over the open window.
Ever see the window net flap when the car is traveling at 200+ MPH?
NASCAR STOCK CARS also have open windows for SAFETY REASONS.
NASCAR STOCK CARS also do NOT have an AC system installed in them.

Driving with the AC ON does not help or hinder your Fuel Economy.
I've gotten well over 30 MPG on very long trips,
while cruising at 75 - 80 MPH with the AC both ON and OFF.
What kills your Fuel economy, is how many times you accept the stop light challenges.

Also, MOST computer controlled cars today, will disable the AC Compressor clutch for several reasons...

WOT - Wide Open Throttle
AC Compresors are NOT built to withstand very high RPMs.

Engine loads - Threshold is programmed into the particular calibration.
When you are accelerating, and your engine reaches a particular calculated work load,
the computer may disable the AC compressor to diminish the work load.

External Ambient Temperature - Many vehicles have an ambient temperature sensor, both inside and outside the vehicle.
If the exterior ambient temp sensor reads below a certain temperture,
the AC Compressor will be disabled in AC mode.
An INTERNAL Ambient sensor can disable the AC Compressor, if a low temperature threshold is reached, inside the vehicle, while the AC Mode is selected.

The HVAC system is not has simple as it was years ago.
It is now more complex than your home HVAC system.

psst....
The AC Compressor is also disabled at WOT on NON-SVT Tours.
Ask anyone with a NON-SVT Tour or Mystique.