Problem Description and Possible Solution
The AC/heater (HVAC) system may unexpectedly switch to the defrost mode when accelerating. This system is operated by engine vacuum and should be inspected for any vacuum leaks if this problem develops. There is also a revised vacuum check valve available to address this concern.
Average mileage: 162,666 (60,000–253,000)
41 people reported this problem
When accelerating with the AC on, the air goes from the vents into the defroster vents. I saw that you had a solution, yet it's too vague for me. Could you tell me about this revised check valve? Does it have a component name, or a part number so I can get one and get my truck fixed? Will I be able to purchase it myself? More info please. Thank you