ac changes from hot to cold over and over .
 

hi and thanks in advance if anyone can help . for a couple of days now when i start my 2000 blazer trailblazer when i try and use the climate controls to turn on the ac it will run for a few seconds cold and the fan speeds ups slows down , then it will change to heat and the fan will speed up then slow down and go back to cool . then back to heat again over and over. also when you turn the key on you hear a buzzing noise . any help would be appericated .

Sounds like your AC compressor is cycling on and off. Pop the hood and watch the clutch on the compressor. If it spins and stops repeatedly it usually indicates that you are low on refrigerant.

ac is fine , now it is stuck blowing straight heat now . so not sure where to start to fix the problem. i'll do a search as i have seen alot of posts about other's having nothing but super hot heat blowing . kinda sticks living in fl right now with heat blowing hehe .