Hi guy. I just go a 2000 blazer and i have code 401 , and i have read all the threads on this code so this weekend it will be fixed hopefully. I also have the auto cilmate contral. It would not cut the ac on ,so i added some 134a to it and it started up ,just low.But it alsowill just go from heat to cool then back and fourth.It even does this when i have the fan switch off< the temp switch at 66 or 82 or anyplace between them can someone help me fix this as i would like to have ac this summer,and no have the 107 heat coming out the vent as it is now. thanks Garry