mod5v is correct. The water valve only closes on max A/C. If you have heat all the time, then the servo motor for the blend air door is bad. I replaced quite a few of these in my days at the C/P house. I converted my old 5th Ave to a cable from an old (late 70s'?) LeBaron from the wrecking yard. Cost almost nothing compared to a new servo, which was more than the 5th was worth . Hope this helps!