Re: 2003 Malibu heater temp on full?!?!
I have the same problem as well with my 2003 V6.
To further make it interesting. I replaced the entire switch cluster for the climate options today and the problem did not fix itself.
Something I noticed, that may need some digging on my part, or someone else's experience, is that the heat control is actually driven through some form of vacuum hose/air hose. It is not resistor based at all. I may try to trace the lines to see what's going on but I'm not sure how far under the dash they go.
Further compounding things, even with a new switch I am unable to use fan settings 1,2,3 only 4,5 work without issue.