2011 GT a/c problem

Discussion in '2011+ Mustang GT 5.0L Tech' started by stevbd, Jul 23, 2018.

  1. stevbd

    stevbd forum member

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    I have a 2011 GT. On hot and humid days, once the AC has been running for about half an hour or so, the airflow through the vents becomes constricted. It still blows cold but it seems like ice is forming somewhere in the system and preventing air to flow through. If I turn it off for a while it goes back to working properly. No wetness on the floors or interior that I can find.

    Any ideas are appreciated. Thanks.
     
  2. ox white

    ox white forum member

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    Have any previous A/C repairs been performed?
     
  3. stevbd

    stevbd forum member

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    No it's worked fine until now.
     
  4. redfirepearlgt

    redfirepearlgt forum member

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    The charge on the system is low. Same thing has happened on my home unit. because the refrigerant is lower, the surface temp on the evap coil is lower. This lower temp causes the condensate to freeze on the coil blocking off air flow. Same thing is happening to your automotive unit. The system needs refrigerant added to it.

    One way to prove this observe under the car with the AC has been running for 10-15 minutes. You should see condensate dripping out. When the coil freezes over after you start feeling the loss in air flowthere will be no condensate dripping. Shut the car off and wait for the coil to begin thawing out and you will begin to see the condensate dripping again as the coil thaws.

    This is all assuming that the air flow is not changing to the floor or defrost vents. If that is the case and air flow is not restricted only redirected, you likely have another issue.
     
  5. stevbd

    stevbd forum member

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    Thank you! One question, why does low refrigerant cause the surface temp on the evap coil to go lower? It seems like it would be the other way around.

    I will try recharging the system. Thanks again for your help.
     
  6. redfirepearlgt

    redfirepearlgt forum member

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    I was afraid you were going to ask me that. My father worked in this industry for 35 years. Just called him to have him explain this to me for the 1001st time. He worked on the primary loops (chillers/compressors,boilers, etc.) in this industry and I worked on the secondary loop side with controls a short time for Johnson Controls where I dealt with them on the HVAC controls side and then would call an expert like him when I determined from basic theory it was a chiller unit or boiler problem. So here it is and please don't ask me to go deeper ! LOL!

    Because the refrigerant is low in the system it has to work harder to transfer the heat that it absorbs across the evap coil and carry it to the condensor coil for removal from the refrigerant and then back into the system again. That causes the temp across the evap coil to drop below 32 degrees and this is when condensate begins to collect and freeze rather than drip off and drain out the bottom of the car through that tube provided. The compressor due to lower suction pressure on its suction side will now also have to work harder and will begin to be on all the time. this will eventually cause the compressor to burn up. So I hope that helps. I had to call the old man and have him dumb it down to me again because he wants to starts getting all technical and using phrases like "As I have explained to you before...". Love the old guy but he gets wound up when asked about it since he has been retired now for 14 years from it.

    This is very dumbed down. But it gives the basics of your problem without having to get into head pressure and suction and all that jazz with regard to high and low side of the refrigeration loop process. I told him I would post his phone number on line if I got follow up questions. LOL! I am JUST KIDDING!
     
  7. stevbd

    stevbd forum member

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    LOL, that actually made some sense. Thank you and thank your dad.
     
  8. ox white

    ox white forum member

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    Yes, a low charge can do that as described above. Sort of rare in an automotive A/C system. However, you need to find and repair the refrigerant leak first as refrigerants are not a consumable. Change the filter too while you are at it.
     
    Last edited: Jul 23, 2018