Frankly, I don't know WHAT the dealer can do. This is a KNOWN issue for years on Altimas.
If you read the New Car Buying Guide by Consumer Reports, it states that the heating is poor even for 2007s. What does this tell you?
Nissan is ignoring the problem - that's what it tells me.
Who's got the time to take the car back time after time after time? I assume if you stick to your guns and DO take it back 3 times or more, it SHOULD fall under the 3 strikes Lemon Law many states have on cars. If the same issue occurrs 3 times and it is still not fixed, something has to be done - get another car, or something....it is the law....