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.
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 :mrgreen:
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.
I have a 2011. I set the temperature knob to "coldest possible" and I get air that is considerably warmer than outside air. ie Outside night air is below freezing on the highway, cabin air is cool but not uncomfortable. Not a problem at this time of year but it seems this would make the air conditioner work when "outside air" should do the job during the warmer months.
I have a similar problem in my 2005. It sometimes blows hot when on cold and smells like smoke. But gauges are fine and engine is fine. Since it is so expensive to replace if you take care of it it should happen less. Turn the temperature control all the way off before turning off your truck (preferably give it a few seconds of being off) and be sure to warm up your truck everytime you cold start and especially when you are going to us A/C. This has worked for me and it rarely happens now.
I have a 2011. I set the temperature knob to "coldest possible" and I get air that is considerably warmer than outside air. ie Outside night air is below freezing on the highway, cabin air is cool but not uncomfortable. Not a problem at this time of year but it seems this would make the air conditioner work when "outside air" should do the job during the warmer months.
If you have any issues like this, please consult the dealership for a proper diagnosis. If you any concerns, please do contact us. I hope this is addressed quickly for you.
I have a similar issue, my compressor will not turn on on its own. I have jumpered the low press plug off the accumulator and it will not engage. I have checked all fuses and replaced the relay with no use. However, while I was trying to remove the relay and check the voltage, the relay cover came off. I then was able to manually move the relay contact and the compressor clicked and cold air came out and the compressor line (smaller one) was cold. Even with the engine off, you can hear the click of the compressor when you push the relay contact.
Is this a low freon type issue, or is it a deeper electrical issue? I have 14vdc at the switch side of the relay, but not at the control side that actually engages the relay.
Thanks
I have the 2001 5.3 manual ac controls
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