Air Conditioning Temp Control

[mrflint]

I've been having a problem with the heating and air conditioning settings. I posted an earlier problem with switching between the two modes as unreliable. My a/c is manual (2002 SES) and lately its been difficult to turn on. When it engages the temp is set to max cold about 7'oclock position. At the 9 o'clock postion, the heat starts to come out of the dash vents. The ac is really coming on but it concerns me that these settings are so extreme. The temp is about 55 during the day and 45 at night, so its not temp extremes. All a/c and heat settings work when they engage. FWIW, before I insert the key, I set the a/c to on, there's a vaccuum sound; this is after the car has been sitting all day or night. THe cold settings must be out adjustment, any suggestions to debug or fix?