appropriate air temperature for rat terrier

Question
Hi - I have a 4 yr old rat terrier / dachsund mix. My wife and I both work during the day and the dog is left at home inside. Question is: What is an approrpiate house temperature to leave the A/C ( or heater in winter) set at for the dog's safety. During the summer, we'd obviously like to leave the A/C on the highest temperature setting to save A/C costs, but in such a way that home harm the dog.  

Answer
 Most people don't think of their dogs in summer.  Since I live where there is no air conditioning I am only guessing. I use fans. I would leave it at a temperature that is just a little warmer than you would normally leave it while you are home and comfortable.  Dogs usually just lay around while you are gone.
 Make sure that there is plenty of water down.  
As far as the winter you can leave it a little cooler and leave a blanket so he can curl up in.  

Hope I helped.
Take care,
Tammy