why is my 98 gmc jimmy cycling hot and cold air, I can here the vent door continually cycling back and forth.
Country: United StatesMake: GMModel: jimmyYear: 1998
replaced duct air sensor
Hello, I am Randall. what is the duct sensor you changed. Do you have the full automatic HVAC climate control
It was a small sensor that is located where the air blows for the heater. Yes it is auto climate control. No matter what setting it is on it does the same thing hot to cold to hot and back again
when I hit accept button it says I will be removed from this chat
Dont do that yet. Still asking questions. Let me gather some info and send. back shortly
Ok, mounted on top and forward on the HVAC case is a small plastic motor called the blend door actuator. It sounds like the gear on end is stripped. rather common failure. the problem is location. You have to pull the dash for such simple part. You can click HERE for that info. In the meantime, you can try recalibrating but it may not work, only shooting ideas
I tried to recalibrate by pulling fuse. waiting replacing fuse turning key back on. I've heard the the gears strip or break but the problem is the door will not move. My door moves it wont stop moving.
#1 in the picture on top front of the case
its computer controlled. the computer has to be signalled it has stopped moving. it cant if gear is bad. the computer is fighting to try and establish a stop location due to temp setting but cant. Its kind of in a open loop
But the door is opening and closing
will the door move if the gear goes bad
I can hear it open come to a stop then immediatly close
I am only shooting my thoughts as have seen this before. I am thinking stripped gear. yes,, it can still move and hit the bad spot, catch and then return the other way continually moving back and forth. I am not saying it is stripped in such that it will not move at all. there are more than just one gear inside, there are several. Its hard to explain. It may be going full one way, hits the one small bad spot, and returns real fast to other direction
The electric air mix door actuator contains a feedback potentiometer. The feedback potentiometer reports the position of the air mix door to the heater and A/C control module. If the air mix door actuator has been removed or replaced for service the actuator must be initialized. Perform the following procedure in order to initialize the actuator:
Shop scanner can view live data from control panel and actuator etc and check for codes. may be you will want diagnsotic before jumping in pulling dash. IMO its going to be bad actuator
I just pulled the dash last week and replaced the heater core. I did not want to do that again since it was working before the heater core was replaced.
Thanks for the help
ASE Master Tech, 35 years, Foreign/Domestic repairs