ok so my sims will NOT change thier tempuratures no matter what i do... ive never used hacks and i dont cheat except for aging off. UNTIL i remembered that to get more pets in my family i used moveobjects on and deleted several of my sims, bread my dogs and made a few puppies, exited to the neighbourhood and then went back to my family causing my deleted sims to come back. I then had 10 family members (4 dogs rest sims). I think that if you have over 8 people, the supposid limit, then your temps will not change. My temps will change for a family of one though. The thing is when i adopted out these pets so i did only have 8 in my family, they're temps still didnt change but i didnt exit and save so that could have been part... IVE WORKED WITH THIS FAMILY FOR SOOO LONG I REALLY DONT WANT TO HAVE TO DESTROY THEM SO THEY CAN HAVE TEMPS... if anyone has anymore ideas or if this has happened to them,, HOLLA

I have read elsewhere that aging off also prevents temperature change.

Some hacks do the same thing:
http://forums.sims2community.com/showthread.php?t=36007

That's odd. My Sims have their aging turned off, and their temperatures changed.

I stopped believing that a long time ago. Many people forget they have hacks or downloaded them unknowingly.