Help needed. A/C blowing hot air

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Mr.Shadetree
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Joined: Fri Apr 30, 2021 7:42 am

Help needed. A/C blowing hot air

Post by Mr.Shadetree »

Hey A/C pros , I just bought a 2010 cobalt that was parked for almost 5 years. I noticed the AC is blowing hot air. Mine you I’m green to this. I learned a little through research. The compressor engages when turned on. The snowflake light on dash is working. I bought a can of AC PRO at Home Depot to refill , assuming it dried up sitting so long, but the gage on the green showing it’s charged when connected to the high pressure side. An AC shop is my last option but I want to exhaust all my options. Can someone help me please?
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JohnHere
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Joined: Sun May 13, 2018 10:20 am
Location: South Carolina Upstate - USA

Re: Help needed. A/C blowing hot air

Post by JohnHere »

It sounds to me like you're getting heated air mixed in with refrigerated air and that it's not the A/C system itself.

I would first check the blend door and the blend-door actuator located under the dash on the passenger side before trying to interpret the system pressures and how much refrigerant the system contains. If the blend door is stuck in heat mode, that will cause the symptom you describe.

The can with the gauge attached can't tell you much of anything about the system other than that it has "some" pressure, and it can actually do more harm than good. So the refrigeration system itself might be fully charged and working fine. Additionally, those recharge kits often contain sealer, which you don't want to introduce into any A/C system. If possible, I would just return the kit for a refund.

If the blend door and actuator prove to be working correctly, I would then do as you suggest and take it to a competent A/C shop for further diagnosis.
Al9
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Location: Southern Europe

Re: Help needed. A/C blowing hot air

Post by Al9 »

This car has a Delphi CVC compressor and a TXV. A particularly low refrigerant charge might still show seemingly ok static pressures, enough to allow compressor clutch engagement, but it will seriously hamper correct compressor displacement regulation by starving the evaporator, and this means warm vent temperatures. The motorboat-like droning noise in this video is the noise this compressor will basically send inside the car's interior through the suction line and the evaporator whenever a TXV type AC system is severely undercharged (the hissing noise is the TXV passing flash gas into the evaporator instead of liquid refrigerant again due to the severe undercharge condition) and, generally speaking, whenever the evaporator is starved and the compressor is operating at minimum displacement at the same time. https://www.youtube.com/watch?v=LvMRfQVtUxg
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