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01 tahoe

Discussion in 'General GM Truck Discussions' started by Coy Lancaster, May 21, 2019.

  1. Coy Lancaster

    Coy LancasterMember

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    My son-in-law has an 01 Tahoe that he's having trouble with the front air. The rear air cools pretty good but the front air doesn't get cold. Is there a valve that could be stuck?
     
  2. 65 sporty

    65 sportyWell-Known Member

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    The front uses a orifice tube, is the blend door going to cold? Is the low side line cold at the evaporator?
     
  3. Coy Lancaster

    Coy LancasterMember

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    Thank you for responding, as far as I know the blend door is working and I'll check the low pressure side line.
     
  4. Coy Lancaster

    Coy LancasterMember

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    I replaced the orifice tube and pulled a vacuum and recharged system. What pressures should I be seeing on the gauges? The front still doesn't cool as good as the rear. The low pressure line going into the firewall gets cold but the one going to dryer is not.
     
  5. 65 sporty

    65 sportyWell-Known Member

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    Pressures should be about 28-30 on the low side and 125-175 on the high side. This would give you good cooling. What are your pressures?
     
  6. 7mopar

    7moparWell-Known Member

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    Those pressures are good at what temperature? My understanding they change with abundant temp.
     
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    • Coy Lancaster

      Coy LancasterMember

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      I was afraid of that my pressures are a lot higher, 60-70 and 200-250. I'm thinking I have a restriction in the system somewhere.
       
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      • 65 sporty

        65 sportyWell-Known Member

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        Around 70, at 90 your high side pressure will be up around 200 psi, but your cooling fan should keep it in check. For good cooling the low side should be around 30 psi when it get's too low say 22 psi the low pressure switch should kick out the compressor.
         
      • 65 sporty

        65 sportyWell-Known Member

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        If you had a restriction you would have low side pressure going into a vacuum or close to it say 5-10 psi, your high side would be very high 400+. How much R-134A is in the system? What is the cooling fan doing? Check the front of the radiator in between the radiator and condenser, you may have to pull the shroud and back wash the radiator. Your pressures are at idle? What are they when you run it up to 2000 rpm?
         
      • Coy Lancaster

        Coy LancasterMember

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        Hey guy's I finally got to get back to the truck and check it out some more. The low side line at fire wall where low side shrader valve is is getting cold. At low idle the compressor is not coming on until you rev engine to about 1500 rpms. Low side will drop to around 40-50 psi the high side goes to 250-300 psi. Does this system have both the expansion valve and the orifice tube?
         
      • 65 sporty

        65 sportyWell-Known Member

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        Yes, orifice tube in front as you know and expansion valve in the rear.

        The compressor wont engage at all until the engine rpm comes up? There is a low pressure switch/cycling switch on the accumulator, it should be closed with pressure in the system. Disconnect it and check for power on one side, if you jump the connector the compressor should kick on.
        The pressures you have are a little on the high side, what's the cooling fan doing? Did you check between the radiator and condenser? You may have to back wash any trash/dirt out.
         
      • Coy Lancaster

        Coy LancasterMember

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        Thanks for the reply I will check the low pressure switch but the condenser is clean
         
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