[CREWZIN]

The reading has nothing to do with the engine or ECU?. I take it you have a newer cruiser as the older models only read the outside temperature on the overhead console. It gets it's reading from a sensor that's located in back of the grill and in front of the radiator.

The computer checks the incoming air for the correct air/fuel mixture by means of a sensor connected to the ribbed air intake located between the air filter and the throttle body.

The service manual indicates that the outside air sensor is not adjustable and must be replaced when faulty. There are two diagnostic tests (sensor and circuit) that your dealer can perform to determine if the sensor is working correctly.

On your second concern about the a/c being terrible at idle ....make sure your fan is running when your at idle and the A/C is on. If not, you might be headed for an overheated condition.