Where does the info come from

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I have a 94 Town Car and the manual says that A/C will not work when
ambient temperature is below 50 degree Farenheit.

Where does the PCM get its reading from.

When I get in at start up the outside temp is reading correct and after the car reaches operating temperature the digital display starts dropping like
a rock to the twenties and teens. The A/C has operated correctly during some of these times and the sensor that controls the dash temp display checks out.

Could another sensor sharing the same ground and perhaps temp controlled
be causing the temp gauge to display an incorret temperature? Perhaps a voltage leak to ground or something. perhaps a bad grond strap?
If so wouldn't other senors on the same grond be affected also

Coolant temp gauge works right. Only the temp..Everytning else on cluster works fine.

I pondered a loose connection but it is almost predictable to when it happens

if my post seems to have been going round and round im sorry this one has my head spinning

Thank you and good luck

[taillight]

The dash guage and the ambient temp guage are different sensors.

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Yes they are. Thanks for confirming that.

My question was could another sensor or switch that shares the same ground cause the reading on the outside temp display to be right on at start up and drop like a rock when car reaches operating temp?

Also A/C will not engage clutch when ambient temp is below 50deg F. Where does that information come from? Does the info go to the PCM and it allows Compressor to turn on or is there a thermal switch built into the compressor itself?

Thanks and Good Luck

[taillight]

Without a wiring diagram, I am not sure but older cars had a seperate temp. sensor by the radiator for the A/C. Newer cars, are wired to the computer. 94 is right about the time they changed.