Page 1 of 2 12 LastLast
Results 1 to 15 of 21

Thread: AC diagnosis

  1. #1
    Join Date
    Jan 2016
    Location
    South NJ
    Posts
    459

    AC diagnosis

    My AC takes forever to cool the car down. The compressor typically cycles on and off every 10 seconds.

    85 degrees out today.
    I put manifold gauges on it, got about 97 psi and 94 psi on low and high sides respectively.

    Car running, AC on full blast. When the compressor cycles on, the low side drops instantly to about 34 psi for a split second then slowly drops to about 18 psi before shutting off. the high side sits around 150 psi when the compressor is on as well.


    Anyone an AC pro in here? M thought was to try to push refrigerant in it. It may be low after 15 years...
    2003 Marauder 300A
    #2928 of 7838
    Build date: 8/6/02
    Ship date: 5/28/03
    14.33 @ 96.82 with OLD engine
    6R80 swap in progress

    1968 Chevelle
    NA/Pump Gas 10.4 @ 128 mph
    416/4L85E LSA Supercharged build underway

  2. #2
    Join Date
    Sep 2015
    Location
    Mississippi
    Posts
    437

    AC diagnosis

    I’m no pro

    But if its low that means you have a leak. It’s a sealed system.

    Low side should read roughly about 45-50psi

    High side should read roughly about 225-250psi

    at 85°

    You can add some to get by but to do it properly you should find the leak and fix it and go ahead and put a new accumulator.

    A lot of members here have said that the bottom of the accumulator rust out that would be a good place to start to look.

  3. #3
    Join Date
    Jan 2016
    Location
    South NJ
    Posts
    459
    Thanks for the tip and the pressure numbers. I know it's sealed, but all AC systems have a very small leak. I think holding perfect pressure for over 15 years is asking a lot.

    This issue has been around since I've bought the car a few years back really. But it has definitely gotten worse. I will try to add and see what happens I guess
    2003 Marauder 300A
    #2928 of 7838
    Build date: 8/6/02
    Ship date: 5/28/03
    14.33 @ 96.82 with OLD engine
    6R80 swap in progress

    1968 Chevelle
    NA/Pump Gas 10.4 @ 128 mph
    416/4L85E LSA Supercharged build underway

  4. #4
    Join Date
    Sep 2015
    Location
    Mississippi
    Posts
    437
    Make sure to check the bottom of the accumulator

  5. #5
    Join Date
    May 2018
    Location
    Winfield, MO USA
    Age
    43
    Posts
    84
    I'm having a similar issue. I was going to post a thread asking the normal pressures. Thank you for this.

    Sent from my SAMSUNG-SM-G930A using Tapatalk

  6. #6
    Join Date
    Jan 2016
    Location
    South NJ
    Posts
    459
    Quote Originally Posted by parker View Post
    Make sure to check the bottom of the accumulator
    What am I checking for? Rust?
    2003 Marauder 300A
    #2928 of 7838
    Build date: 8/6/02
    Ship date: 5/28/03
    14.33 @ 96.82 with OLD engine
    6R80 swap in progress

    1968 Chevelle
    NA/Pump Gas 10.4 @ 128 mph
    416/4L85E LSA Supercharged build underway

  7. #7
    Join Date
    Feb 2017
    Location
    New Orleans, LA
    Posts
    262
    typically the most common failure is the main seal on the compressor, they get old with age and when not used for a while they tend to leak rapidly when used again until it seals up if it does at all. That's why its best to run the ac at least once a month even in the winter.

    You can get the full a/c replacement 4 seasons kit from autozone for a little over $300 or so. it includes a new compressor, lubricant, CORRECT accumulator, orifice valve and generic o-ring kit.

    Since you didn't loose your charge you don't have to worry about flushing the lines or condenser. Be sure to put only a couple ounces of oil in the compressor and the rest in the accumulator despite what they recommend otherwise you'll make a mess and loose most of it. And its important to spin the compressor a handful of times before charging to get the oil to circulate in the compressor preventing a dry startup.

    Also another common problem to look out for. With the aluminum blocks the ac compressor threads tend to get stripped very easily on the block. Take your time and make sure its lined up 100% and hand tightened all the way before attempting to tighten any of them.

  8. #8
    Join Date
    Jan 2004
    Location
    Somewhere in the N.C. Triangle
    Age
    68
    Posts
    26,250
    Quote Originally Posted by 376shovel View Post
    My AC takes forever to cool the car down. The compressor typically cycles on and off every 10 seconds.

    85 degrees out today.
    I put manifold gauges on it, got about 97 psi and 94 psi on low and high sides respectively.

    Car running, AC on full blast. When the compressor cycles on, the low side drops instantly to about 34 psi for a split second then slowly drops to about 18 psi before shutting off. the high side sits around 150 psi when the compressor is on as well.


    Anyone an AC pro in here? M thought was to try to push refrigerant in it. It may be low after 15 years...
    If the compressor is cycling, the system is low on freon. A/C systems are closed. If your low on freon that means there is a leak.
    “When you can’t make them see the light, make them feel the heat.”
    Ronald Regan

    "The only way to deal with the Islamic State - these blood thirsty, blood-drunken, terrorists -
    is to kill them, keep on killing them, until you kill the last one, then you kill his pet goat."

    Lt. Colonel Ralph Peters

    “Be polite, be professional, but have a plan to kill everybody you meet.”
    "I come in peace. I didn't bring artillery. But I'm pleading with you, with tears in my eyes, if you **** with me, I'll kill you all"
    General James Mattis




  9. #9
    Join Date
    Jan 2004
    Location
    Somewhere in the N.C. Triangle
    Age
    68
    Posts
    26,250
    Quote Originally Posted by decipha View Post
    typically the most common failure is the main seal on the compressor, they get old with age and when not used for a while they tend to leak rapidly when used again until it seals up if it does at all. That's why its best to run the ac at least once a month even in the winter.

    You can get the full a/c replacement 4 seasons kit from autozone for a little over $300 or so. it includes a new compressor, lubricant, CORRECT accumulator, orifice valve and generic o-ring kit.

    Since you didn't loose your charge you don't have to worry about flushing the lines or condenser. Be sure to put only a couple ounces of oil in the compressor and the rest in the accumulator despite what they recommend otherwise you'll make a mess and loose most of it. And its important to spin the compressor a handful of times before charging to get the oil to circulate in the compressor preventing a dry startup.

    Also another common problem to look out for. With the aluminum blocks the ac compressor threads tend to get stripped very easily on the block. Take your time and make sure its lined up 100% and hand tightened all the way before attempting to tighten any of them.
    Modern automobile HVAC systems run the compressor periodically even in the winter which will keep the seal in good condition. It runs mostly to remove excess humidity.
    “When you can’t make them see the light, make them feel the heat.”
    Ronald Regan

    "The only way to deal with the Islamic State - these blood thirsty, blood-drunken, terrorists -
    is to kill them, keep on killing them, until you kill the last one, then you kill his pet goat."

    Lt. Colonel Ralph Peters

    “Be polite, be professional, but have a plan to kill everybody you meet.”
    "I come in peace. I didn't bring artillery. But I'm pleading with you, with tears in my eyes, if you **** with me, I'll kill you all"
    General James Mattis




  10. #10
    Join Date
    Jan 2004
    Location
    Somewhere in the N.C. Triangle
    Age
    68
    Posts
    26,250
    If you don't have the proper tools and knowledge, I'd recommend taking it to a professional.

    I'd also get an aluminum receiver dryer.
    “When you can’t make them see the light, make them feel the heat.”
    Ronald Regan

    "The only way to deal with the Islamic State - these blood thirsty, blood-drunken, terrorists -
    is to kill them, keep on killing them, until you kill the last one, then you kill his pet goat."

    Lt. Colonel Ralph Peters

    “Be polite, be professional, but have a plan to kill everybody you meet.”
    "I come in peace. I didn't bring artillery. But I'm pleading with you, with tears in my eyes, if you **** with me, I'll kill you all"
    General James Mattis




  11. #11
    Join Date
    Jan 2016
    Location
    South NJ
    Posts
    459
    Do you have a part number for the aluminum dryer? I have a manifold set, I can go buy a vacuum pump.

    I understand the systems are sealed, but I've read on the topic a while ago and remember the documentation saying all AC systems slow leak over the years. In other words it wont hold the charge for decades. I'm hoping it's just because it's old and has probably never been serviced.
    2003 Marauder 300A
    #2928 of 7838
    Build date: 8/6/02
    Ship date: 5/28/03
    14.33 @ 96.82 with OLD engine
    6R80 swap in progress

    1968 Chevelle
    NA/Pump Gas 10.4 @ 128 mph
    416/4L85E LSA Supercharged build underway

  12. #12
    Join Date
    Sep 2015
    Location
    Mississippi
    Posts
    437
    Quote Originally Posted by 376shovel View Post
    What am I checking for? Rust?


    Yes, you’ll have to peel off the insulation thats on it.

    I collects the Condensation from when you run your a/c and from rain and rust overtime.

  13. #13
    Join Date
    Sep 2005
    Location
    APPLE VALLEY,CA
    Age
    59
    Posts
    1,366
    Replace your BCM. IT is probably fried.

  14. #14
    Join Date
    Jan 2016
    Location
    South NJ
    Posts
    459
    Quote Originally Posted by BLACKMARAUDER04 View Post
    Replace your BCM. IT is probably fried.
    Out of left field. What makes you say that?
    2003 Marauder 300A
    #2928 of 7838
    Build date: 8/6/02
    Ship date: 5/28/03
    14.33 @ 96.82 with OLD engine
    6R80 swap in progress

    1968 Chevelle
    NA/Pump Gas 10.4 @ 128 mph
    416/4L85E LSA Supercharged build underway

  15. #15
    Join Date
    Jan 2004
    Location
    Somewhere in the N.C. Triangle
    Age
    68
    Posts
    26,250
    Quote Originally Posted by 376shovel View Post
    Do you have a part number for the aluminum dryer? I have a manifold set, I can go buy a vacuum pump.

    I understand the systems are sealed, but I've read on the topic a while ago and remember the documentation saying all AC systems slow leak over the years. In other words it wont hold the charge for decades. I'm hoping it's just because it's old and has probably never been serviced.
    I bought my MM in '04, brand new. Never had the A/C serviced and it's still as cold as the first day I drove it.
    “When you can’t make them see the light, make them feel the heat.”
    Ronald Regan

    "The only way to deal with the Islamic State - these blood thirsty, blood-drunken, terrorists -
    is to kill them, keep on killing them, until you kill the last one, then you kill his pet goat."

    Lt. Colonel Ralph Peters

    “Be polite, be professional, but have a plan to kill everybody you meet.”
    "I come in peace. I didn't bring artillery. But I'm pleading with you, with tears in my eyes, if you **** with me, I'll kill you all"
    General James Mattis




Page 1 of 2 12 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Alternator Diagnosis
    By magindat in forum Shop Talk
    Replies: 3
    Last Post: 05-09-2011, 09:36 AM
  2. Diagnosis please?
    By Vostok in forum Shop Talk
    Replies: 17
    Last Post: 10-06-2010, 11:35 AM
  3. Diagnosis begins
    By 94_302 in forum Steering, Suspension & Brakes
    Replies: 5
    Last Post: 09-26-2010, 06:30 AM
  4. Chevy Tow Diagnosis
    By davidholland in forum The Lounge
    Replies: 3
    Last Post: 10-30-2007, 10:34 AM
  5. Air Pump Diagnosis?
    By Heavy351 in forum Shop Talk
    Replies: 4
    Last Post: 02-26-2006, 05:37 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •