Results 1 to 17 of 17

A/C stops blowing under mild acceleration

This is a discussion on A/C stops blowing under mild acceleration within the General Help forums, part of the LSx Technical Help Section category; I know the clutch on the compressor is supposed to disengage under hard acceleration but even at say 1800 rpms ...

  1. #1
    Junior Member
    Join Date
    May 2007
    Location
    New Orleans
    Posts
    29

    Silver
    1998 Ram Air T/A

    A/C stops blowing under mild acceleration

    I know the clutch on the compressor is supposed to disengage under hard acceleration but even at say 1800 rpms it shuts off not only the compressor but the blower also. It seems like it may be a vaccum problem but I had it checked out as thorough as possible and the system is holding vaccum.
    Any thoughts into this issue would be greatly appreciated.

  2. #2
    The Bandit Wesman's Avatar
    Join Date
    Apr 2006
    Location
    NJ
    Posts
    4,033

    SGM
    1998 Trans Am WS6

    Perhaps the clutch on the compressor is going bad, and under acceleration, it starts slipping and therefore the compressor stops turning. Something to check out.
    Last edited by Wesman; 07-19-2007 at 12:17 PM.

  3. #3
    Impounded MikeSomething's Avatar
    Join Date
    Dec 2005
    Location
    Old Bridge, NJ
    Age
    36
    Posts
    1,420

    Pewter Metallic
    '00 Z/28

    Sounds like a bad diverter valve.

  4. #4
    Senior Member SeVeReDiStOrTiOn's Avatar
    Join Date
    Aug 2005
    Location
    Roseville, CA
    Posts
    8,164

    05 Wrangler
    00 Z28 sold :-(

    The HVAC fan shuts off also?

  5. #5
    Junior Member
    Join Date
    May 2007
    Location
    New Orleans
    Posts
    29

    Silver
    1998 Ram Air T/A

    Yes, I thought that was unusual. I am trying to determine if I can feel some cold air directed at my legs when this happens. When the air from the dash vents shuts off it does feel like there is cold air from under the dash near the console. So maybe if the air is that cold then the compressor is not shutting off but the vent doors are freaking out.

  6. #6
    Senior Member SeVeReDiStOrTiOn's Avatar
    Join Date
    Aug 2005
    Location
    Roseville, CA
    Posts
    8,164

    05 Wrangler
    00 Z28 sold :-(

    Check the vaccum switch thingy to the rear and on the driverside of the intake manifold. You'll know it when you see it...it's not very big and has several vaccum lines going to it.

  7. #7
    Senior Member greatwhiteZ28's Avatar
    Join Date
    Nov 2006
    Location
    d
    Age
    32
    Posts
    3,675

    white
    2002 z28

    its somewhat normal casue mine does it when i turn the steering wheel hard or brake hard, not sure which onw it effects but it turns off for like a milasecond

  8. #8
    Senior Member SeVeReDiStOrTiOn's Avatar
    Join Date
    Aug 2005
    Location
    Roseville, CA
    Posts
    8,164

    05 Wrangler
    00 Z28 sold :-(

    it shouldn't...check all your vaccum lines and that switch mentioned earlier

  9. #9
    Senior Member slims00ls1z28's Avatar
    Join Date
    Apr 2007
    Location
    TN
    Posts
    1,212

    2005 GTO M6 Black
    2000 Z28 A4 Red

    Blower shouldn't be cutting off because of vacuum. I might divert it from dash to vent or something like that but it shouldn't cut off thats electrical. If the blower cuts off I'd check around for loose grounds somewhere.

  10. #10
    Member Fastcar's Avatar
    Join Date
    Dec 2005
    Location
    Jersey Boy
    Posts
    316

    Dark blue metallic
    2000 TransAm

    Quote Originally Posted by MikeSomething View Post
    Sounds like a bad diverter valve.
    Mike hit it right on the nose: what causes the A/C to stop blowing out of the dash vents is caused by low vacuum on acceleration. The A/C works fine when you start cruising again, right? I had the same problem, but my system failed completely and blew air out of the heater (foot) and defroster vents only, all of the time. My vacuum diverter valve cracked and caused a big enough vacuum leak to create this condition. The replacement valve worked for about a week, then cracked again! My mechanic didn't know why that happened, so he put in a metal valve: the factory part is plastic. Worked fine after that; my mechanic explained that the heater/defroster vent default operation was designed that way for safety. If your vacuum system malfunctioned during the wintertime, you would still have defrost to keep the windshield clear. You may have a small vacuum leak; even after the repair, my A/C still does the heater/defroster vent operation under hard acceleration. I guess that if you want to eliminate the problem completely you'd have to install a vacuum reservoir.

  11. #11
    UberTapping Friction Pimp Anthracis's Avatar
    Join Date
    Mar 2007
    Location
    Omar's Tittie Taverna & Grill, Deh Rawod
    Posts
    1,447

    18D Cock Diesel
    1999 Z28; 98 SS #2043 RIP

    Mine has a gremlin too and I can't figure out the problem. I wonder if my compressor is going out. My AC whines when driving slow in the city and stops cooling. Only hot air blows. But on the freeway, it blows cool air. But sometimes it blows hot air. Other times the belt whines like its slipping when the AC is on but when I turn off AC, its fine. WTF? Can anyone help?
    "I am the executioner. When a crime is committed and the exalted state does not take vengeance nor move to punish, then comes time for the executioner to declare himself. I have waited long enough. The criminals are hereby sentenced to death. By fire. By earth. By water."

  12. #12
    Junior Member
    Join Date
    May 2007
    Location
    New Orleans
    Posts
    29

    Silver
    1998 Ram Air T/A

    Quote Originally Posted by Fastcar View Post
    Mike hit it right on the nose: what causes the A/C to stop blowing out of the dash vents is caused by low vacuum on acceleration. The A/C works fine when you start cruising again, right? I had the same problem, but my system failed completely and blew air out of the heater (foot) and defroster vents only, all of the time. My vacuum diverter valve cracked and caused a big enough vacuum leak to create this condition. The replacement valve worked for about a week, then cracked again! My mechanic didn't know why that happened, so he put in a metal valve: the factory part is plastic. Worked fine after that; my mechanic explained that the heater/defroster vent default operation was designed that way for safety. If your vacuum system malfunctioned during the wintertime, you would still have defrost to keep the windshield clear. You may have a small vacuum leak; even after the repair, my A/C still does the heater/defroster vent operation under hard acceleration. I guess that if you want to eliminate the problem completely you'd have to install a vacuum reservoir.
    My mechanic changed the diverter valve and the car has a vacuum canister on it from the factory. The system pulls and holds vacuum as it should. I will agree that it is a vacuum problem and I'm wondering if when the previous owner installed the headers they took off some vacuum lines and put them on incorrectly. BTW the cold air does come from the heater and defrost vent. I was wondering why on a humid night the winshield kept fogging up by the vent.

  13. #13
    Member Fastcar's Avatar
    Join Date
    Dec 2005
    Location
    Jersey Boy
    Posts
    316

    Dark blue metallic
    2000 TransAm

    Yep. You have a vacuum problem somewhere.

  14. #14
    Member
    Join Date
    Aug 2005
    Location
    Virgina
    Posts
    224

    Black
    98 Trans Am

    Quote Originally Posted by Fastcar View Post
    Mike hit it right on the nose: what causes the A/C to stop blowing out of the dash vents is caused by low vacuum on acceleration. The A/C works fine when you start cruising again, right? I had the same problem, but my system failed completely and blew air out of the heater (foot) and defroster vents only, all of the time. My vacuum diverter valve cracked and caused a big enough vacuum leak to create this condition. The replacement valve worked for about a week, then cracked again! My mechanic didn't know why that happened, so he put in a metal valve: the factory part is plastic. Worked fine after that; my mechanic explained that the heater/defroster vent default operation was designed that way for safety. If your vacuum system malfunctioned during the wintertime, you would still have defrost to keep the windshield clear. You may have a small vacuum leak; even after the repair, my A/C still does the heater/defroster vent operation under hard acceleration. I guess that if you want to eliminate the problem completely you'd have to install a vacuum reservoir.
    Where did you get the metal valve? I keep breaking/cracking the plastic ones too.....

  15. #15
    Senior Member Chaos's Avatar
    Join Date
    Aug 2002
    Location
    Denver/Las Vegas/Norcal
    Posts
    836

    Silver
    2002 WS6

    well shit, my car has been doing that since new. blows out the vents and at a certain point while accelerating the air is diverted to the feet, then returns when I back off the throttle. I thought it was normal this whole time. so it's not? lol
    2002 WS6 aka "Mr.Brownstone"


    My car is my heroin

  16. #16
    Member Fastcar's Avatar
    Join Date
    Dec 2005
    Location
    Jersey Boy
    Posts
    316

    Dark blue metallic
    2000 TransAm

    Quote Originally Posted by IronBird View Post
    Where did you get the metal valve? I keep breaking/cracking the plastic ones too.....
    I think that my mechanic somehow adapted or substituted a metal tee that would fit in place of the valve. I was a bit concerned that it wasn't a true valve, but he said that the vacuum system would still work fine (which it does to this day, more than 4 months since he put in the metal tee). I guess that he was right, and I've had no problems since.

  17. #17
    Member
    Join Date
    Aug 2005
    Location
    Virgina
    Posts
    224

    Black
    98 Trans Am

    I started to just "tee" it, but did not know if it would damage anything without the actual "valve" part. I always wondered though...what that valve was "checking"....to much suction? With my luck, if I tried without it, it would suck the hvac into the intake! Thanx for the 'gitbak man.

Thread Information

Users Browsing this Thread

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

Bookmarks

Posting Permissions

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