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B7 RS4 evaporator temperature high

Drivebyracing Jul 18, 2019

  1. Drivebyracing

    Drivebyracing New Member

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    Hi guys, struggling a bit with the ac, not long had the car, long story short it had had three compressors in the last 2 years with previous owner. It then blew the 4th up on me a week after owning it. The system was full of swarf and the orifice filter was blocked solid. I have cleaned out the lines, replaced the compressor, condenser, pressure sensor, drier and the filter. The system now works and has no faults, I have also reopened the filter to check for any remaining swarf to which there is none.

    My problem now is although the system works it doesn’t seem cold enough, even though the pressures are good, the gas and oil quantities are good, the pipes get cold an condense, fan runs etc etc. Pop on VCDS and my evaporator temp is 8-10 degrees. My understanding is it should be more 2-3 degrees.

    Can anyone shed any light on the situation as I’m getting a bit stumped now.

    Also this doesn’t matter whether it’s on auto (climate control) or at a set temp

    Thanks
     
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  3. gary3306

    gary3306 Well-Known Member TeamMisano Gold Supporter VCDS Map User TDi Audi A6 Audi Avant Owner Group Black Edition S-line owners group

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    First thing that springs to mind for me is the quantity of refrigerant that's in there (enough in to bring the pump in, but not enough for efficient cooling). If it HAS got the correct quantity in, maybe there is still moisture within the system. When replacing parts I always vacuum down for a good hour prior to filling to boil off all moisture. If there is moisture there it starts to freeze in the orifice tube and plug the hole, resulting in warm(er) air. The warm air then melts the ice plug and the system goes cold again for a short time until the moisture freezes the hole up again, and so it continues. Also check the carbon filter/pollen filter in the car and check it isn't choked up. Other than that it is a bit of a puzzler because its a fairly simple system.
     
    Last edited: Aug 10, 2019
  4. Drivebyracing

    Drivebyracing New Member

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    Hi Gary, cheers for the reply. Still pickling me now. I’ve forgotten to add I’ve removed the gas 2-3 times since to check the amount of refrigerant and to re check the orifice tube. Both the tube and refrigerant quantity were spot on so I am at a complete loss. Pollen has been changed also. The only two things I can think is the interior air temp sensor faulty in the climate unit itself. Or a faulty evaporator temp sensor? But both read a temp and alter. It’s. It like they register open circuit codes or read -40 etc. Really getting to me now to be fair
     
  5. gary3306

    gary3306 Well-Known Member TeamMisano Gold Supporter VCDS Map User TDi Audi A6 Audi Avant Owner Group Black Edition S-line owners group

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    Is the hot/cold control operating correctly?
     
  6. Drivebyracing

    Drivebyracing New Member

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    Yep, works fine, hot to cold. It’s just like it’s a few degrees out as you get to the colder temperatures
     

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