H2 HVAC issues

[boarral]

I was wondering if anyone might have any suggestions to help resolve an intermittent HVAC issue that I have?



HVAC has operated correctly since I purchased my 2005 H2 SUT until this past week. What happens is that when I switch to defrost, (and sometimes just adjust the temperature), I start getting cold air blasting out of the defrosters. At this point, adjusting the temperature, switching to auto, or manually moving the air from vents to defrost to feet, etc. does nothing. It continues to blow cold air. On auto, as the vehicle cools down, it begins to output air faster and faster, as if the auto mode is honestly attempting to try heating up the vehicle faster, but instead of hot air coming out, it's just more cold air.



Every time this occurs, turning the vehicle off and back on resolves the issue. Sometimes for days, other times only until I adjust the temperature again, at which point the whole thing occurs over again. This also happened with my last H2, though it was near the end of my owning it, so I didn't bother attempting to resolve it.



Any suggestions? <img src='http://www.canadianhummerclub.com/forum ... /smile.gif' class='bbc_emoticon' alt=':)' />

[boarral]

I have been researching this issue and have a couple things to try, one of them being cranking the heat to full hot when it does it next, to override the temperature sensor. I don't believe I've tried this yet. I have also read of ways to recalibrate the internal temperature sensor through pulling the battery then reconnecting it and turning the HVAC system on full hot or full cold. Something about the system recalibrating the sensor during the first 40 seconds of operation or something.



Either way, something to try. I'm hoping it's not the temperature sensor itself as I've heard the part is expensive and if it's the passenger side one, it's a pain in the arse to get at. The driver one is in the headliner, I believe.



I hope I can resolve this soon. It was miserable at times on the trail this weekend waiting for a chance to restart the vehicle. I was either freezing or sweating.

[HummerBee]

[quote name='boarral' timestamp='1321903058' post='32935']





Either way, something to try. I'm hoping it's not the temperature sensor itself as I've heard the part is expensive and if it's the passenger side one, it's a pain in the arse to get at. The driver one is in the headliner, I believe.

[/quote]



My 05 SUV was only blowing cold air on any setting unless it was set to max temp. It was the driver side temp sensor in the headliner. $56 for the sensor, $63 for diagnostic, $90 labor for install. This was at the local GM dealer.

[boarral]

[quote name='HummerBee' timestamp='1321922973' post='32947']

My 05 SUV was only blowing cold air on any setting unless it was set to max temp. It was the driver side temp sensor in the headliner. $56 for the sensor, $63 for diagnostic, $90 labor for install. This was at the local GM dealer.

[/quote]



That's not bad at all. If I can start reproducing this more, I'll get it to the dealership. <img src='http://www.canadianhummerclub.com/forum ... /smile.gif' class='bbc_emoticon' alt=':)' /> Thanks!