Air condition blows out warm air

check for compressor clutch operation, if the clutch is engageing you could have a bad compressor or a blockage in expansion valve

First things first.....You must have the air conditioning system hooked up to an a/c system machine and then checked for leaks and also read low and high side pressures. If there are leaks then low Freon (R134a) content and low refrigerant oil can cause the a/c system to not engage the a/c compressor which basically means you will not have proper defrost functionality nor regular air conditioning. Most shops, when working with your air conditioning, will install air conditioning dye to assist them in locating leaks and is the first step in diagnosing all a/c systems. Post the findings after thw

You need to check the freon level and if that is good check the compressor. If you have no pressure on the low side, when I say pressure on low side I mean vacuum, then most likely the compressor is bad or you have a leak someplace. You can get a freon fill kit at Walmart, Target, Auto Zone and most any auto parts stores. These kits comes with a gauge and connection hose. Typically if the freon is low the compressor won't activate. Connect the fill hose to the low Side of your AC and turn the AC on to Maximum with the engine running. If its a low freon problem the compressor will start to kick in as the pressure increases. Make sure you don't overfill the system as this will cause a seal or line to blow. Being a 1998 your vehicle should use R134A freon which is what can legally be purchased by a home mechanic. It cost about $12 to $20 a can and usually includes a leak detector additive and seal conditioner.

I would recommend that you check the fuse panel in your vehicle and make sure that the a/c fuse is good, then I would recommend that you raise the hood, turn your a/c on in the car, and then see if the compressor is cycling on and off. If the fuse is good, then there is a chance that your compressor is low on freon, so you should check this, and if it is low, then charging it should resolve the issue. The second problem is finding out where the leak is that caused the system to lose freon. To do this you will need to add dye to the system and see where it leaks. If the freon level is where it is supposed to be, then you may be looking at a faulty compressor, and will need to replace it, and with that you will need to recharge the system.

I have a feeling that no one is checking the blend door in the plenum.

first check your fuses and any relays sometimes you have multible relays that are the same in a fuse box that you can switch around but i would bet you have a leak either in your compressor or in your line if the clutch is not kicking on and off or running all the time when you turn it on thats because your freon has leaked out the system is sealed freon does not go bad if there is no pressure in the system it will just blow warm air your question is vague so if your blower is not blowing bad blower motor or a fuse if warm not getting cold your system has a leak if you have not broke the system you can try stop leak 2 cans to seal a leaky compressor compressor could be bad if it wont spin noisy clutch could be bad need new compressor but if a leak after stop leak add the right amount or r-134a 2 to 3 cans if the compressor kicks on on the first can of stop leak or freon your system did leak down and you hope the stop leak fixes it but first check all your lines are tight and that the freon is not leaking from the high or low pressure ports the valve can leak sometimes make sure your caps are on take some spit after you add freon back into your system see if your spit blows a bubble if it does replace or tighten the valve. a few things to check start with power fuses then add a can of freon if you have power now clutch engagement if you add and kicks on there is the reason a leaky system it will all leak back out in a day or several days... thats why you can add the stop leak things you can try or take it to the shop and pay someone some $$$$$

If your car is more than a few years old, it probably has a leak or a worn compressor. You can add too much freon for the system. It needs to be vacuumed down to a negative pressure before adding freon, and then checked for compressor function and leaks. You may need to take it in to a reputable shop.

If the A/C is not working, meaning it blows warm air, it is either very low on Freon or has none at all. This could be the result of a bad compressor, bad connection, or bad line. The only way to know what problem you have is to do a UV leak test. If the leak is in a rubber hose, o-ring, or seal you can use a leak repair kit which will seal most leaks for about a year. If the compressor is bad you'll need to replace it.

The Air-conditioning needs to be re-gassed. Take the car to an Auto Mechanic to get the Air-Conditioning re-gassed. They might also need to check it for leaks to make sure the gas stays in.

U may be low in Freon gas.
When Freon is low there's low pressure switch that will prevent A/C compressor clutch from engaging to protect it from failure.
So, first check Freon pressure & any leaks form lines & hoses fittings.
Even if the fan is working, that doesn’t indicate proper compressor OP'S.
Look at the compressor front side you'll see the clutch stationary while the AFT pulley moving.

Then put air-condition compressor switch to ON (Engage),
You should see the clutch engage & start rotate,
If NOT, this is very clear indication u r low in Freon.

Regards;
MAR