NO ac

You've probably got a vacuum leak from a hose in the engine compartment, or a plugged vacuum line. Sometimes it's just a hose not completely pushed onto the nipple or one that has rubbed against something just enough to create a leak. Carefully check each vacuum hose, and any one-way valves fitted in the vacuum lines. To find a plugged line you have to check each and every hose related to the vacuum system. Identify where you have vacuum at one end of the hose but have nothing at the other end. You can find a leaking line a couple of ways. First, with the hood open, listen for a hissing sound all around the intake of the engine starting with the vacuum manifold, as well as the manifold. It helps if you have a mechanics stethoscope but you can use a plastic or PVC pipe, just stay clear of any moving parts. If you are careful, you can use a can of carburetor cleaner with the red tube attached and spray small amounts of it along where the vacuum hoses run in the engine compartment, including around the power brake booster & hose. As you spray small amounts along those lines, if there is a leak it will draw the carb cleaner in and cause the engine to slow down a bit. This is the method I use, it works fast to identify leaks, but you must be careful. WARNING: Only do this a bit at a time and let the engine compartment air out. Carb cleaner is flammable. You could also have a HVAC switch problem, but that is rare.