What should I take apart and look at? Is the cold hot knob just a valve that lets hot water into the heater core? Or is it more complicated then ...

What should I take apart and look at?
Is the cold hot knob just a valve that lets hot water into the heater core?
Or is it more complicated then that?

In a '99 it's more complicated. They don't valve the heater core anymore.

First thing is... is your compressor on when you turn on the air?
If no, do you have 12-14v at the compressor clutch? If yes, then your compressor clutch coil is likely shot, the question then is: can you turn the compressor by hand. TURN OFF THE ENGINE FIRST.

Most every a/c not working problem is a class on a/c troubleshooting. If you really want to do as much as you can by yourself, get a Hayne's or Chilton's manual. The owners manual will tell you to take it to the dealer.

Looking at your question again, are you even asking about a/c or are you getting hot air out of the vents all of the time? If that's the case, you may have a blend door issue. If you want to take stuff apart, start with the a/c control and see if you have burnt contacts. You could ohm out the rheostat to see if that works properly.

Hope this gives you a place to start. I know it's a lot of stuff, but this ain't a model T.

The air conditioning does not work, it will be fixed in a few weeks, when I am supposed to get fresh air it only blows warm air. I have not a clue how to ohm out anything. I will probably just pay someone to look at it. Thanks.

Is this a single or dual climate?

koolz71 wrote:Is this a single or dual climate?

Single

You didn't answer silversurfer's question about the compressor . Is it coming on at all ? If it is then it probably is a control head issue . If not , then more than likely you are low on freon or be a bad compressor too but sometimes the plug on the compressor can get loose . I've seen people unplug them and clean them and it will come on . This is more of a long shot though . 9 times out of 10 it's low freon level . Do you know where the accumulator is ? IT's the the big silver cylinder by the firewall . On the side of that is a plug . This is the low pressure safety switch . This is an easy one . Unplug it and take a small piece of wire with the ends stripped off and bend it into a U shape and plug that into the female plug (the wires you unplugged).A paper clip also works. Now does your compressor come on ? If so , you're low on freon . Perhaps you have a friend who can help you put some in . You can buy the cans of freon with the little gauge and the proper connector already there . You would keep the little piece of wire there until you get enough freon in the truck . If you've got a really slow leak it can save you some money right now and get you through the summer. Of course only do this if the compressor is not coming on . You can't hurt anything by trying this . Let us know what shakes out

Yes the compressor comes on and it blows cool air for about a min, I know it's just low on freon.
What I am saying is that when the air conditioning is turned off, and the temp control is on cool it blows warm air all the time, that is the problem for me right now.

Does it stay on or does it cycle (on and off over and over ) ? If so , this is the low pressure switch doing it's job.