i recently bought a 01 suburban. I am having problems with the front heat not always switching over to hot. The other problem i am having is that the rear heat is not blowing anything at all. If i turn the rear heat on you can hear it in the back sounds like its on but its not blowing nothing out and the same for in the middle i can turn it on but its not blowing nothing out. Any help would be greatly appreciated and please bare with me cause i am completely new to the suburbans but not new to working on cars. Thanks a lot in advance