Why doesn’t my air conditioner not blow cold air when truck is idling?

Hi @grannyv ,

Don’t know the answer but maybe check if the A/C compressor is turning off at idle.

It may be that there isn’t enough voltage from the alternator at idle to keep it or perhaps its' control circuit on.

Do the vehicle headlights dim at idle also?

If so, measure the voltage on the battery terminals with the engine idling. It should measure 13.8V -14.5V DC.

Be safety aware when doing this. Ensure that the vehicle is in park (AT) or neutral (MT) and that the handbrake (emergency brake) is firmly applied. Also watch where you place your hands, tools etc as the engine is running

Also measure the battery voltage with the engine off. A good battery should read ~12.5V DC. Anything <11.0V DC should be investigated as to the possible cause e.g. faulty alternator, faulty voltage regulator, faulty battery, loose or corroded battery cable connections etc.