One or more heater & AC (HVAC) temperature and/or air delivery mode door actuator may fail, resulting in improper temperature or air delivery. If this occurs, fault code(s) should be stored in the HVAC control module which should assist in diagnoses.
Improper HVAC Temperature and/or Air Delivery Due to Failed Mode Door Actuator on GMC Suburban 1500
Average mileage: 336,000 (336,000–336,000)
9 people reported this problem
1999 GMC Suburban 1500 336,000 mi, Visitor
my ac quit while going up a mountain on a dual lane hwy at 65 mph....the air that was coming out the vents on the dash was cold & fine until it abruptly switched to the vents on the floor and soon after was coming out hot air....the lights on the ac dash panel were no longer on and i had to lower the windows turning the ac off..and still do not know what is causing it not to work.....replaced the relay in the fuse box under the hood, put guages on on the lines & it hasn't lost any freon ...checked all the fuses & replaced all that were blown.....noticed that the fuse box on the drivers side of dash has two relays & the top one was so hot it burned my fingers...replaced it & the new one does the same thing, so i pulled it & left it out for i feared it would start a fire under the dash..now when my wife wants to use the car i plug it back in & set the seat where she likes it & pull it out leaving it out till i reset the seat for me....I would like to know how to fix this problem....