I have a 1990 Chev Silverado 4X4 w/ 4.3L V-6. I had a new A/C system put in 6 months ago and system works very well except the automatic re-circulating system comes on only when it feels like it. Usually once a week. As I live if Fla. this is not good enough. This problem was occurring before I put the new A/C system in.
Is there a switch or sensor that may be bad? I checked whether the vacuum was OK and it seems to be. I have plenty of vacuum. I need a way to check this automatic re-circulating system. Thank you