Hot AC

baronalmbaronalm Member Posts: 1
edited August 2015 in Chevrolet
Hey guys,
I will try and keep this short. I have read quite a few threads to attempt to solve my problem without posting, to no avail.
My wife has an '09 Tahoe that recently began blowing only warm air up front with slightly cooler air in the rear when all set on high AC. The fans are blowing strong and are fairly clean and undamaged, no seen issues with the blend doors as all selections correspond with what is selected, bought some AC Pro with a gauge that read around 52 pounds obviously on the low press port, when the AC is on, the compressor clutch engages beautifully...

So obviously I have an issue. My questions and info to all you gracious professionals...
1) For a 2009 Tahoe, is a reading of 52 on the low port indicative of over pressurization? And would that cause warm air with AC? I did not add any refrigerant after seeing that. When the AC is turned off, the reading spikes past the "red" and "pegs out". Is that normal? I have never serviced or messed with this AC system as we have never had any issues. It has always blown so cold, you needed a Parka. Obviously I am ignorant on this topic. I did notice that on the line with the larger port (I'm assuming the high pressure port), with the AC running, the line from the port back toward the firewall was ice cold and just before the line reaches the port, it's significantly hot (right past the connection of this main line). Is that normal?

2) Here is an event preceding the problem. 2 weeks ago, we took a trip to Gulf Shores AL from Ft Worth Texas and about 3/4 of the way, on the passenger side, under the dash, water/condensation began dripping on my wife's feet (A drop or two every 15-30 seconds) and the carpet eventually became damp. Upon some hard turns, it poured out from under there. It was not raining and the water was ice cold. This has been happening intermittently since that trip. Is this a common problem? We've never noticed this before. Indicative of a clogged line? 

Again fellas, I've read through a lot of material here and I am still lost. I'm kind of partial to not using dealerships because my [non-permissible content removed] and frankly I don't really have the time. If I can get away with a potentially simple fix, that would be awesome!

I absolutely appreciate all your guys' help and comments!
Thank you.

  UPDATE: The AC got cold for a few days and is back to good ol warm only. I'm attaching a picture of the high pressure line and port is. The straight part of the line with the port is hot when running and the line just on the other side of where it is coupled/joined and where the 90 degree turn is, it is nice and freezing cold like and coolant line is supposed to be. Is it normal for that line to be hot right there? 


  • joejoesonjoejoeson Member Posts: 44
    52 PSI seems a little bit high for the low side, perhaps you have air in the system, but a Tahoe is a big vehicle so I'm not entirely sure, I tried to look up the specs but couldn't find where the low side should be at, one source said 30-50, so 52 would be over the high side of those figures, but I can't verify the accuracy of those specs. I'll just give you the basics and maybe that will help you sort things out:

    The thicker pipe which has a blue cap is the low side, it should be cold. The thinner pipe with a red cap is the high side, which should be hot. If you can test the PSI of the low side, why not also of the high side? If the high side is somewhere around 170 PSI or so, that should be a good range. Generally a low side is around 20 PSI so your 52 seems unreasonably high, which could cause poor AC performance and will cause the refrigerant to run too hot (which is why it's blowing hot air). Too much overcharging can cause liquid refrigerant into the compressor and destroy it. Or air leaked into the system while it was recharging.

    Honestly if you don't know what you are doing, you should probably not mess around with it because refrigerant can be very dangerous to your body and also you might damage your AC components, especially if it is a simple fix like it is overcharged. Have you bought a refrigerant canister at an autozone and pumped it in yourself? That would probably explain the overcharged state.

    If you take your car to a mechanic shop and ask them to do an evacuation and recharge, it shouldn't cost more than 100 dollars or so (it's a very simply operation and newer machines practically do it all for you). This will ensure you have the correct amount of refrigerant in your system. Since you said the AC was back to cold for a few days, I'll hope that you didn't destroy your compressor.
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