No AC. Please help!

[CapitalMark]

My 02 Yukon only blows hot air. I adjust the temp control and no matter what it stays at it's hottest. Last I checked the AC clutch was engaging when the AC button was pressed. Also, not sure if this is relevant, but the battery died during the winter and it needed to be replaced. Heard somehow that could have something to do with resetting the temp control? Any help is much appreciated.

---------- Post added at 12:13 AM ---------- Previous post was at 12:12 AM ----------

Checked AC coolant and it was good.

 

[OR VietVet]

Does sound like the battery replacement may have effected the temp control. I think there is other threads about this but If I recall you just unhook the battery again for about 15 minutes and see if it did recalibrate.

 

[CapitalMark]

Thanks raiderron. I'm going to try that now.

 

[01ssreda4]

Did it work?

 

[OR VietVet]

I guess he didn't have 15 minutes right then?

 

[CapitalMark]

Hey guys, nope, unfortunately I didn't get around to it last night, been waiting for the rain to stop here to try tonight. I really hope it works. Do I have to start the engine with the AC on, or any other trickery to get it to work?

 

[OR VietVet]

Not that I know of.

 

[CapitalMark]

So good news and bad news. I did what was recommended, and sure enough the temperature now adjusts out of hot only. Which is a huge improvement. Unfortunately when I turn it to cold it only comes out barely cool. Guess I have to check freon levels again.

 

[OR VietVet]

Need to know how long the compressor clutch engages for and what the pressure is at the low side, at least. Best if give us the high and low pressures when the clutch is disengaged and when it engages and how long it engages. Sounds like is low on refrigerant. R134A. If do add R134A then just do a can and then give pressures before adding the can and after and how long the clutch engages after the added can. If you put a thermostat in the vents to check how cool remember this: Always check at center vent for a more accurate reading. Initially you can check on high fan speed but the true temp and colder temp will be on low fan speed. Less fan turbulence means a colder temp reading. That is why the best way to do it when first start out driving with a/c on is to get the heat out with the high fan speed and then adjust fan speed down to get the colder temp.

 

[CapitalMark]

Thank you so much, Ron! Probably have to wait until Thursday to get to it, but I'll update when it's done. I really appreciate your help.

 

[OR VietVet]

Hey, I am just glad the battery trick allowed the system to recalibrate and now if there is another weak link, like there appears to be, we can go from there. Good luck and let us know.

 

[CapitalMark]

Fixed!!!!! So I went to track auto and bought one of those can refills of freon. When I connected it my pressure read almost 0. I turned the AC on and started to fill when in about 15 seconds I heard the compressor kick on. This was actually the first time I've heard it. Anyway, I ended up draining the tank and it's just below the "green" on the pressure gauge. It's not ice cold, but dramatically colder than it was. I think with a few more pounds of freon it should do the trick. Not sure exactly what the Temps are, but once I add more freon I'll test and let you know. Thank you for all of your help.

 

[OR VietVet]

DO NOT, I REPEAT, DO NOT add a few more pounds of Freon. That would be too much. The whole system will likely only need 2 more cans to be close to full. Add another can and then check pressure and temp and get back here. Too much will damage the compressor.

 

[CapitalMark]

Ok, so I added another can and it only brought it up a little bit. That little bit put it in the green, but not within the boundaries of the arrows it had me set according to the ambient air temp. It emptied the entire second can. So I decided to get a third can. I added at and it didn't increase the pressure at all. Think I almost emptied the 3rd can. At that point I figured it shouldn't need anymore regardless of what the gauge said. Only concern I have now is I kept hearing the compressor kick on and off while the pressure was low. Now I don't hear the compressor powering on and off, but air is nice and cold. Should I be worried?

 

[OR VietVet]

No stop where you are at. You have some air in the system that should have been evacuated but was not so it will not take a full charge. When you are driving it will cycle at the compressor. Bear in mind the reason it was empty is because you have a leak. Not sure how big a leak till you drive and see how quick you may get low enough to make a temp difference. Drive it and enjoy the cold air. Look at the condenser in front of the radiator and check for debris. If can get to it then pull it off if is there. Need that air flow there. Remember what I said about fan speed. Let us know what happens as you drive it. Kind of cool huh? Battery disconnect to recalibrate and add 3 cans and now is blowing cool. Got to love it!

 

[CapitalMark]

I know, I couldn't believe it. I bought this truck at auction for $1,000. It's by far my favorite vehicle I've ever owned. She has lots of miles on her, but you can tell the previous owners had great pride of ownership. Only one owner before me. Lots of little things wrong with her, but I'm getting to them. Need to replace 02 sensor, and I have an issue with a ground wire somewhere I think. Horn doesn't work, and every now and then when I turn on one of my turn signals the other one faintly lights up. Found a ground wire about 4 months ago and connected it and everything was working again including the horn, but then it suddenly stopped again. I can hear the relay under the hood clicking when I press on the horn, just no sound. May try purchasing a new horn and replacing it. Ron, you are a wealth of knowledge, man. I really appreciate all your help.

 

[OR VietVet]

You will find numerous ground wires under the hood and near the frame areas and the firewall. Find them all and clean and reattach snugly and go from there. Check all connections at horn and ground at horn and at relay and make sure is clean and tight connection.

Always replace the O2 sensor with AC Delco brand at Rock Auto and if can afford do all of them since they are likely the same age. The day before you try to remove them spray some PB Blaster at the threads a couple of different times and let that work at the threads. Make sure you use the correct size wrench to remove. Best to use box end of wrench after unplug the sensor wire and snake the wrench over it or if can use a 6 point socket that fits tight. The best penetrant is called Aero Kroil and is about $20-$25 a can but is the absolute best there is.