2005 Suburban LT.
In the past, any time the battery went dead or was disconnected for whatever reason, the climate controls would freak out for a bit and blow full hot on driver and passenger sides. After some time, they'd re-calibrate and start working normally. I know this somewhat common/normal so, I wasn't too concerned.
Now, again, both sides blow hot regardless of temp setting and have been after several days and several attempts at re-calibrating the system. Mode selector works as does fresh air actuator, just stuck on full hot on both sides.
I did the trouble shooting method described here http://www.sparkys-answers.com/2009/09/2004-chevrolet-tahoe-blows-hot-air.html and found I have no control voltage. It's supposed to be 0v to move in one direction, 5v to move in the opposite direction and 2.5v to stay steady.
From reading online, it appears as if one actuator goes bad, it could effect the whole system so I bought 3 new actuators, both the driver/passenger hot/cold actuators and the fresh air actuator. Installed, a pain it was, reconnected battery and left to re-calibrate...same problem.
One thing I notice is, when the system is re-calibrating, the passenger side hot/cold actuator and the fresh air actuator actually sweep fully, as they should, from one end to the other. The driver hot/cold actuator does not do this but, it's my understanding that it should.
So, since the symptoms are identical with all new actuators as they were with the old, it leaves me thinking the problem is either with the HVAC control head or with the BCM.
Anyone have experience with diagnosing these systems? How can I troubleshoot it beyond what I've done?
Also, I know that when replacing a BCM it requires programming. What about if replacing with a used BCM from a vehicle with the same options? Does it still require reprogramming or should it all work?
In the past, any time the battery went dead or was disconnected for whatever reason, the climate controls would freak out for a bit and blow full hot on driver and passenger sides. After some time, they'd re-calibrate and start working normally. I know this somewhat common/normal so, I wasn't too concerned.
Now, again, both sides blow hot regardless of temp setting and have been after several days and several attempts at re-calibrating the system. Mode selector works as does fresh air actuator, just stuck on full hot on both sides.
I did the trouble shooting method described here http://www.sparkys-answers.com/2009/09/2004-chevrolet-tahoe-blows-hot-air.html and found I have no control voltage. It's supposed to be 0v to move in one direction, 5v to move in the opposite direction and 2.5v to stay steady.
From reading online, it appears as if one actuator goes bad, it could effect the whole system so I bought 3 new actuators, both the driver/passenger hot/cold actuators and the fresh air actuator. Installed, a pain it was, reconnected battery and left to re-calibrate...same problem.
One thing I notice is, when the system is re-calibrating, the passenger side hot/cold actuator and the fresh air actuator actually sweep fully, as they should, from one end to the other. The driver hot/cold actuator does not do this but, it's my understanding that it should.
So, since the symptoms are identical with all new actuators as they were with the old, it leaves me thinking the problem is either with the HVAC control head or with the BCM.
Anyone have experience with diagnosing these systems? How can I troubleshoot it beyond what I've done?
Also, I know that when replacing a BCM it requires programming. What about if replacing with a used BCM from a vehicle with the same options? Does it still require reprogramming or should it all work?
