my heater and AC blow very very very hot air... not matter what i have it set on... even if the heat is on and set on low... it blows very hot air.... the thermostat on the dast reads normal.... what can it be? how do i fix it?
When you turn the A/C on, does the motor lag like the compressor is kicking on? Mine did that last summer, and I couldn't figure out what it was. I took it in and the guy replaced a $30 sensor, and it works just fine now! Don't know if that is what your problem is or not, but worth a shot.........Wish I could remember what he called the sensor. Evidently the computer and the compressor weren't talking, and it would try to kick on, but then shut right back off, and all I got was hot air. Hope that helped a little. You could just try calling an auto shop, and they should know what the sensor is called.
there is a low pressure switch , and a high pressure switch located in most ac systems , if one of these safety's is bad the compressor will short cycle or not run at all. the hot hot air, i would look first into my vaccume lines that control the heat/ac. i had just the opposite problem in a 98 taurus and found that a mouse or something had eaten one of my vaccume lines and as a result i got no heat at all. if an ac system has too much refrigerant in it you can lose superheat and slug your compressor, low referigerant levels will cause too much superheat and cause the compressor to get too hot . burnt refrigerant turns acidic and can ruin internal compressor parts as the referigerant cools the compressor. there is usualy a head pressure control valve (headmaster of sorts) which will make the high pressure reach a certain pressure/temperature point before it lets it go on to the condensor coil. this valve lets your ac run when outdoor ambient temp is below 60deg F for your defrost ect..
because it blows really hot on both heat and a/c it's a blend door problem.
there is a push pull cable that runs from the climate control head in the dash ( the knob you turn to change temp) and it go to the blend door motor on the heater box..
Looks like everything has been covered here.The basic checks you could do is to run the car and turn on ac,pop the hood and visually check to see if the ac clutch is engaging.If it is rapidly clicking on and off there is low freon,not engaging at all could be no freon or as others have said a pressure switch problem.One other check is to visually look at the hoses,ac clutch etc for oil where freon may have leaked out.If your ac compressor is running you can check the hoses from compressor.Small hose will be hot to touch and large hose cool.If that is the case then it is probably a blend air door problem or temp switch/cable problem.
I actually have a similar issue on my expedition. On the Expedition, the temperature control knob is stripped (at least thats the best way I could come up with to describe it). So if I spin the temp knob from hot to cold, nothing moves in the actual switch. Pull off the temperature knob and see if you can adjust the temperature with a pair of needle nose pliers. If that doesn't adjust the temperature, check what the others said.