A/c problems My 2003 KIA Spectra blows hot air when the blower is on and in the AC position. The system is fully charged and the compressor does not come on.

You need to ensure the engine is running when you are testing the AC or heating systems, as they rely upon a compressor to work the heat pump.

If your engine is on when you are testing this and no different temp air comes out, you should ensure your AC system is properly charged with coolant and that the compressor is engaging and functioning. If not, it will need to be replaced.

It is low on coolent,

The question is: why isn't the compressor clutch turning

The compressor isn't likely seized,it may leak refrigerant,
but won't be what your asking.

The clutch can be jumped to test that

If okey, then you have to diagnose the entire
A/C Electrical System

How do you know it is properly charged,you put
refrigerant gauges on the system?

do you hear the blower running if not then it could be a bad blower motor or a bad relay.hope this helps you.

does the blower motor come on when you want heat,or even blow air on any setting, if not you may need to change the blower,

if the compressor works and your freon is charged it may be the blower flapper door....disconnect battery for 10 minutes and then re-connect to reset the electronics that control the flapper

I had a similar problem with the A/C unit not blowing cold air, even though the compressor and bottle were running and charged. It turns out that there are two baffles under the dash that are moved around by two brassy colored arms. Both arms had become separated from the baffles, preventing the cold air from reaching the cabin. The other baffle control the direction of the air (panel, floor, defrost). Check those baffles to see if they are properly connected to the brassy control arms.

This is typical of a leak in the a/c system, or a faulty compressor clutch, or compressor. Check to make sure that the system has refrigerant, if it does, turn the a/c on and go check to see that the compressor clutch is engaging, if it isn't and the system is fully charged, then you most likely either have a faulty clutch solenoid, or a faulty pressure switch on the charge can.

Have you changed your filter lately?
This is what happened to my car as well. I live in woody area and we had a very big fire in October 2007,(yeah it was California) and because it was winter I did not notice until Summer hit.
Also if it was changed to late there maybe stuff inside of the blowers.

Cost. Depending on the filer you would like to use ( reusable or not) I would save about 20 dollars just to be safe.
Cost for the checking the hoses and stuff, I am not sure, but if you know anyone in the mechanical buss this is the time to ask a favor because you know that they will give you an honest result and tell you how much it should cost. Or ask a friend of a friend kinda thing. Trust me I live in San Deigo, CA and we get a big bill for small things, but because we don't know the people. It is worth it in the end to know of someone.

Check your pressures again. Jump the pressure switch and see if this makes the compressor come on. If it does then jump it long enough to get some more freon into the system. This should give switch enough pressure.

Make sure your vacuum is good on the system before you fill.