I bought this car with 32k mi now at 65k: Came with a clean carfax/auto check (not 100% accurate I know). At first I loved this car it only needed the TPMS sensors replaced which I could live without. We here I am a year and a half later and wish I hadn't purchased this lemon... Lets see:
So far I have had to replace: Rotors,Pads (normal), Front engine motor mount, power steering pump return line, HVAC blender solenoid (i think its going out again). It needs a fuel pump sending unit(got to buy the whole pump), now has a #1 Cylinder misfire (which is way to common to not recall), Shifts hard so transmission work is in my future. All with daily commuting.. no real rough driving
The 325hp V8 ... thats about it...
Stand behind your vehicle.... I expect little things here and there... but all these problems and just at 65,000 miles... seems to me GM was in a rush to push this car out and now refuses to recall anything because it takes someone dieing or being badly hurt to initiate a recall for some of the stuff...
If i do not miss my guess afte many years of experience with chevy v6 and transmission set-ups..i would bet your heater and tranny woes are tied together...their is likely a common vacuum supplky for both..look for a point where they branch off..one back to the firewall to the heater controls and one to the transmission,likely a leak or broken connection is someone about and could be anywhere along the vacuum supply route.Look closely anywhere the line touches metal and especially at the junction place.That would cause both systems to screw up..by the way the hard shift , if due to vacuum loss, will not harm the tranny ,in fact is easier on it then the smooth shift we all prefer as the smoothness is due to built in slippage which is where wear happens.But past a certain point none of us want a hard shift,and that vacuum source could well be the problem and needs fixed.Anytimne you have a harder shift appear AND hvac mess-up at same time on a chevy,,suspect that vacuum junction and /or the vacuum supply at some point along it's route.