1. Welcome to Tundras.com!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Tundra discussion topics
    • Transfer over your build thread from a different forum to this one
    • Communicate privately with other Tundra owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

2001 Tundra, AC warm, pressure at 75psi, no leaks, comp clutch engages. What’s next?

Discussion in '1st Gen Tundras (2000-2006)' started by phreaktor, Jun 20, 2021.

  1. Jun 20, 2021 at 8:22 PM
    #1
    phreaktor

    phreaktor [OP] New Member

    Joined:
    Jun 20, 2021
    Member:
    #64561
    Messages:
    13
    Gender:
    Male
    Hi guys. My first time posting here and I’m working on my dad’s 2001 4.7L Tundra that blows warm air. The compressor clutch is responding to the AC switch and I measured the low side at 75psi (using a refill kit gauge), which is very high, correct?

    After some reading here, I just realized I can check the high side as well. What tool do I need to do that, considering the refill kit’s hose only fits the low side? What should the nominal reading be for each side? Is it even necessary to check the high side or should I be looking elsewhere?

    I don’t know much about AC systems, but from what I’ve seen on general YouTube videos, there’s a valve in the cab somewhere before the evaporator that opens the low side return. Is it possible this valve is stuck closed and I’m just reading the static pressure in the line from the valve to the compressor low side port? What is my next logical troubleshooting point?

    Lastly, can anyone point me to a exploded view of the system or the factory service manual? Thanks in advance for any advice you guys can offer!
     
  2. Jun 20, 2021 at 10:29 PM
    #2
    Tundra2

    Tundra2 Zoinked

    Joined:
    Feb 10, 2019
    Member:
    #25875
    Messages:
    12,058
    Gender:
    Male
    First Name:
    Noah
    Western Kentucky
    Vehicle:
    '00 Tundra V8 SR5 '03 Corolla Virus
    I'm not an AC expert, so I'm no help there.. The only thing I can suggest to check is the blend door that's actuated by the hot/cold knob on the HVAC bezel.

    The connecting rod from the knob goes to a valve pictured below. Denoted by the blue arrow. (Below is V6 engine bay. V8 blend valve should be in similar location.)
    20210621_002550.jpg

    Turn the knob all the way to HOT, and take a picture of the valve. Turn it all the way to cold, and take a picture of it.

    Post them here. If it's not moving you'll have to pull the HVAC bezel out which is easy, and see what's not connected/broken.

    This is the only thing I can offer as help. Perhaps others may know more. @Professional Hand Model @FrenchToasty @Darkness @bmf4069
     
  3. Jun 20, 2021 at 11:12 PM
    #3
    Darkness

    Darkness Allergic to white

    Joined:
    Jul 23, 2018
    Member:
    #17315
    Messages:
    9,976
    Gender:
    Male
    First Name:
    Luis
    All over SoCal
    Vehicle:
    The darkest
    It's really dark
    I'm not good on AC stuff. There are a few things on cars that I consider black magic. Window tint, properly installing gears, transmission work, and AC work.
     
    bmf4069 and Tundra2 like this.
  4. Jun 21, 2021 at 3:58 AM
    #4
    phreaktor

    phreaktor [OP] New Member

    Joined:
    Jun 20, 2021
    Member:
    #64561
    Messages:
    13
    Gender:
    Male
    Wait so if the knob for the AC is completely missing, the AC will not function? Because the knob is broken and not in position. I used pliers to rotate the square shaft to the cold position. Thank you for the reply.
     
    Tundra2 likes this.
  5. Jun 21, 2021 at 4:06 AM
    #5
    Tundra2

    Tundra2 Zoinked

    Joined:
    Feb 10, 2019
    Member:
    #25875
    Messages:
    12,058
    Gender:
    Male
    First Name:
    Noah
    Western Kentucky
    Vehicle:
    '00 Tundra V8 SR5 '03 Corolla Virus
    The AC will still function, but if you turn the knob, and that valve in the engine bay doesn't open with heat, or close with cold then you'll constantly be blowing hot air if it's stuck open. The AC isn't stout enough to knock the heater core heat out of the air.

    Also, I have a set of these cheap knobs because one of mine broke too.

    Link
     
  6. Jun 21, 2021 at 4:38 AM
    #6
    phreaktor

    phreaktor [OP] New Member

    Joined:
    Jun 20, 2021
    Member:
    #64561
    Messages:
    13
    Gender:
    Male
    Wow my Dad is gonna be so happy if this is the problem. Thank you so much. I will update once I head back over there. :)
     
    Tundra2 likes this.
  7. Jun 21, 2021 at 5:48 AM
    #7
    phreaktor

    phreaktor [OP] New Member

    Joined:
    Jun 20, 2021
    Member:
    #64561
    Messages:
    13
    Gender:
    Male
    Oh wait... I see what you mean. It’s not the knob being broken off, but the square shaft being disconnected from the valve that could be the issue. I wonder if he could have damaged it when turning it with pliers. It seemed to turn with the normal resistance when I did it last night.
     
  8. Jun 21, 2021 at 9:33 AM
    #8
    KNABORES

    KNABORES Sarcasm incoming

    Joined:
    Jan 1, 2020
    Member:
    #40572
    Messages:
    10,074
    Gender:
    Male
    Arkansas
    Vehicle:
    2000 Limited TRD AC 4X4 Thunder Grey 270k miles. 2019 Limited TRD CM 4x4 Cement Grey 75k miles
    2000: Bilstein 5100's 16x8 589's with 265/75/16 and 1.25" spacers Flowmaster 50 series over the axle dump Pioneer touchscreen with backup camera Full interior and dash LED conversion Trailer brake controller with 7 pin Bedliner coat bumpers & trim ARE topper 2019: ARE topper with full Bedrug kit and Vortex rack TRD shifter 1.25" wheel spacers (I like to live dangerously) Red tow hooks for that +15 grip bonus
    I am also no A/C expert, but 75 on the low side with the system running in max A/C mode is way too high. Should be closer to 40-50 depending on outside temps. I wouldn't mess with measuring the highside, I would take it to an A/C shop for a diagnostic. Many offer the "summer tune-up specials" for a reasonable price. They can let you know if they find any issues. Sounds like you are overcharged though to start with.
     
  9. Jun 21, 2021 at 11:01 AM
    #9
    Festerw

    Festerw New Member

    Joined:
    May 7, 2017
    Member:
    #7600
    Messages:
    3,771
    Gender:
    Male
    Cambridge Springs, PA
    Vehicle:
    04 Tundra DC
    This. A/C isn't difficult but without the proper tools and knowledge it's pretty easy to do some damage. Even the dealers here run a $30 AC inspection, last one I had done cost me $50 to add some refrigerant.
     
  10. Jun 22, 2021 at 6:21 AM
    #10
    phreaktor

    phreaktor [OP] New Member

    Joined:
    Jun 20, 2021
    Member:
    #64561
    Messages:
    13
    Gender:
    Male
    Do anyone know the part number/name of the valve on the firewall that’s connected to the temp control? I’m going to do a little more diagnostic (pinch off the coolant hose between the control and knob) and then put it in the shop if I can’t get anywhere. The shop is the last resort.

    A friend told me these refill kits at AutoZone with the digital fill gauge can give false readings. This is the tool I used to measure the low side. Does anyone have experience with them?
     
  11. Jun 22, 2021 at 8:48 AM
    #11
    tvpierce

    tvpierce Formerly New Member

    Joined:
    May 6, 2019
    Member:
    #30129
    Messages:
    1,329
    Maine
    Vehicle:
    2000 Tundra AC SR5 4WD, 4.7 Automatic
    I have a similar set of knobs as the ones @Tundra2 linked, since two of mine were broken when I bought the truck. They work very well... buy a set for your dad as a late Father's Day present. :thumbsup:

    When you adjust the middle Temperature knob two things should happen:
    1) the coolant control valve that @Tundra2 showed in the pic opens/closes to regulate the flow of hot coolant to the heat exchanger in the cab.
    2) the blend door in the HVAC system opens/closes to route air from the fan to/away from the heat exchanger.

    To check #1, do as @Tundra2 suggested and look at the position of the valve under the hood, then go and change the position of the center control knob, then go observe the valve again. If the position of the valve changed, then that's working.

    To check #2, lay on your back on the passenger side floor looking up at the HVAC system -- right above where the passenger's feet would be, toward the center. Move the heat control knob and see if the cable moves that actuates the blend door. If it moves, that's working.

    Both of these tasks are more easily done with a helper. So if Dad is available, have him sit in the driver's seat and work the Temperature control.
     
  12. Jun 22, 2021 at 9:53 PM
    #12
    phreaktor

    phreaktor [OP] New Member

    Joined:
    Jun 20, 2021
    Member:
    #64561
    Messages:
    13
    Gender:
    Male
    Thank you for that explanation. I’ll be there tomorrow to go through all the suggested steps.
     
  13. Jun 22, 2021 at 10:03 PM
    #13
    phreaktor

    phreaktor [OP] New Member

    Joined:
    Jun 20, 2021
    Member:
    #64561
    Messages:
    13
    Gender:
    Male
  14. Jun 23, 2021 at 5:18 PM
    #14
    phreaktor

    phreaktor [OP] New Member

    Joined:
    Jun 20, 2021
    Member:
    #64561
    Messages:
    13
    Gender:
    Male
    He stopped by for a quick minute today and I checked the water valve on the firewall. It functions normally. The right hose is hot and the left is just warm, if that matters.

    Something he brought up- there is an ongoing issue with the main radiator fan where the clutch seems to be engaged and the fan runs just about all the time. Is this related to the AC issue? Could the constant running of the fan have damaged the AC compressor?

    I also checked the sight glass on the cylindrical part where you can see the refrigerant bubbling. When the motor is held at 1500RPM, there is foaming present in the sight glass non-stop, when it’s supposed to appear and go away.

    There’s a section in the FSM that uses the symptoms seen there to indicate what could be a problem. It says this indicates that the refrigerant is “low” which is weird considering I measured 75PSI on the low side. The section is attached below.

    5988FA89-66EA-4813-A756-9CF9A5F47F65.jpg
     
  15. Jun 23, 2021 at 5:34 PM
    #15
    Professional Hand Model

    Professional Hand Model A.K.A ‘Golden Hands’

    Joined:
    Apr 29, 2018
    Member:
    #14878
    Messages:
    15,004
    Gender:
    Male
    First Name:
    Fred
    ‘Somewhere’... a State of Mind
    Vehicle:
    2002 Tundra SR5 4WD 4.7L AC Silver Metallica
    Hand Protectors
    Radiator Fan will run all the time. How fast/slow is determined by Ambient Temp affecting the Silicone Oil inside and engaging/disengaging the coils. Should have nothing to do with your A/C and how it operates unless the fan isn’t pulling in air over the A/C Condenser at all (ie not working). If this was the case your Engine Radiator would overheat, as well.

    As far as the Bubbles and your high PSI, I am unsure.
     
  16. Jun 23, 2021 at 10:58 PM
    #16
    KKJC2654

    KKJC2654 New Member

    Joined:
    Jun 21, 2021
    Member:
    #64587
    Messages:
    20
    Gender:
    Male
    Vehicle:
    2000 Tundra 4.7
    75 psi is too high. Low side too high and high side too low indicates compressor internal failure 90% of the time but you cannot see the high side in your case. Normal loss over a long period is expected. Evac and recharge most places is around 100-150 depending on location. If your technician pulls a vacuum on the system and it doesnt hold then you have a leak in which case they should not charge the system (further diag required). If it holds then they will charge it full with no air intrusion like you get with those garbage freon kits from local store. Worth it to take it in and theres a reason specialist are called well... specialists.
     
  17. Jun 24, 2021 at 3:58 AM
    #17
    gargra03

    gargra03 New Member

    Joined:
    Feb 12, 2021
    Member:
    #58990
    Messages:
    23
    Gender:
    Male
    First Name:
    Gary
    Vehicle:
    2005 Tundra DC
    leveling kit MT Tires LED Camper Shell
    Agreed, I am an AC tech, Take it into a reliable shop and have them throw a set of gauges on it. They will be able to diagnose and will save you time and money.
     
  18. Jun 24, 2021 at 9:17 AM
    #18
    phreaktor

    phreaktor [OP] New Member

    Joined:
    Jun 20, 2021
    Member:
    #64561
    Messages:
    13
    Gender:
    Male
    What chain shops offer AC diagnostics and service? Like Midas, Mieneke, Jiffy Lube etc...
     
  19. Jun 24, 2021 at 4:17 PM
    #19
    KKJC2654

    KKJC2654 New Member

    Joined:
    Jun 21, 2021
    Member:
    #64587
    Messages:
    20
    Gender:
    Male
    Vehicle:
    2000 Tundra 4.7
    ice cold air does down here in FL. They charge 100 bucks to look at it no matter where you go to pay the tech for their time. IF you choose not to purchase the work, then you pay the diag. If you choose to do the job they wave the 100 bucks in most cases.
     
  20. Jun 25, 2021 at 7:16 AM
    #20
    phreaktor

    phreaktor [OP] New Member

    Joined:
    Jun 20, 2021
    Member:
    #64561
    Messages:
    13
    Gender:
    Male
    I have an appointment at Pep Boys next week. $63 diagnostic fee. I will update.
     

Products Discussed in

To Top