A/C problem 2001 sts
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Cadillac Seville / Cadillac Eldorado Forum Discussion, A/C problem 2001 sts in Past Cadillac Vehicle Discussion; Hi guys need to pick ur brains a bit ... All winter long the compressor cycled on as it should ...
  1. #1
    vinndiesel is offline Cadillac Owners Member
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    A/C problem 2001 sts

    Hi guys need to pick ur brains a bit ... All winter long the compressor cycled on as it should but when it got a little warm in jersey a couple of weeks ago my old faithful let me down ... No compressor operation and no codes pertaining to ac ... No low ac refrigerant message .. When I jump relay it turns on but doesn't get cold ... Doesn't build pressure pipes have no change it temp. My question is if the compressor fail internally shouldn't the clutch still engage

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    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
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    Re: A/c problem 2001 sts

    Time for a trip to a GOOD A/C shop. System checkout, vacuum evacuation, recharge by recommended PAG amount and r134a weight............ probably replace the orifice tube and filter/dryer. Normal for the age, especially if you simply leave the system in AUTO year-round.

  4. #3
    basscatt's Avatar
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    Re: A/c problem 2001 sts

    Quote Originally Posted by vinndiesel View Post
    Hi guys need to pick ur brains a bit ... All winter long the compressor cycled on as it should but when it got a little warm in jersey a couple of weeks ago my old faithful let me down ... No compressor operation and no codes pertaining to ac ... No low ac refrigerant message .. When I jump relay it turns on but doesn't get cold ... Doesn't build pressure pipes have no change it temp. My question is if the compressor fail internally shouldn't the clutch still engage
    ==========================
    to diagnose AC problems -
    you need to connect a quality set of guages -

    then post BOTH the HIGH pressure readings -
    and the LOW pressure readings -

    along with the ambient - outside - air temp -

    and the air discharge temp at the center AC vent -
    with the temp set at 60* and a medium speed fan - with the engine at a high idle - 1500 rpm -

  5. #4
    vinndiesel is offline Cadillac Owners Member
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    I have a set of good gauges not reading any pressure even when I jump compressor relay ... If it were low on freon it would display a message right ... No message and no clutch response even if I try to pull in some freon

  6. #5
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: A/c problem 2001 sts

    The PCM disables the compressor to prevent damage when low on refrigerant. When it gets that low you should have low refrigerant body code. If you have NO pressure, the system is empty and you certainly should have a "B" code (no SES light), but you should also have a SERVICE A/C message.

  7. #6
    vinndiesel is offline Cadillac Owners Member
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    That's just it no codes or service ac ... Where is the low pressure switch on this car ... And is there a pressure switch on compressor that would cause clutch not to engage

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    Ranger's Avatar
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    Re: A/c problem 2001 sts

    I believe that the compressor has an over pressure sensor in it. Low pressure sensor is #29

    http://www.gmpartsgiant.com/Page_Pro...PartSortBy=Key

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    Mark C's Avatar
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    Re: A/c problem 2001 sts

    You only get the low pressure code once, when it occurs. I had it a couple of years ago and after it came in and was acknowledged it never showed up again even though the pressure was still low. Reset your codes and see if it comes back, mine didn't but the compressor worked for 20 or 30 seconds then went back to being disabled but I didn't get the low Freon low pressure code after each of these temporary resets, and the code wasn't in the current or history lists. Once the system was evacuated and recharged it worked fine. Mines a 2000 STS.

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    vinndiesel is offline Cadillac Owners Member
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    Ok first thanks for all the info ... I had some time to play around with the car last night and went back to the basics and tried giving it a taste of freon .. And wallah the compressor kicked in ..and it was only a small amount so I let it run and it worked as it should ... So I went a step further and evacuated the system replaced the dryer and orifice tube and recharged system and works perfect ... Thanks for all ur support ... What thru me was the car is so smart in most cases and I relied on it to tell me what was wrong instead of going back to the basics

  11. #10
    Ranger's Avatar
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    Re: A/C problem 2001 sts

    Is it safe to assume that you drew a vacuum before recharging the system?

  12. #11
    vinndiesel is offline Cadillac Owners Member
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    Yes had it under vacuum for an hour and a half and recharged ... System is working fine but I noticed the driver side vents aren't as cold as the passenger side ... If I play around with the knob it seems to get colder but still not as cold as the other side ... I'm sure it has something to do with the ambient sensors in the ducts

  13. #12
    basscatt's Avatar
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    Re: A/C problem 2001 sts

    Quote Originally Posted by vinndiesel View Post
    Yes had it under vacuum for an hour and a half and recharged ... System is working fine but I noticed the driver side vents aren't as cold as the passenger side ... If I play around with the knob it seems to get colder but still not as cold as the other side ... I'm sure it has something to do with the ambient sensors in the ducts
    -------------------------------
    I noticed the driver side vents aren't as cold as the passenger side
    assuming there are no problems with the mix doors -
    and you have the passenger side temp turned off -

    if you needed to add freon - the system has a leak -

    the new charge of freon is already less than full -
    that is probably causing the difference in duct temps -

    the liquid freon is already turning to a gas before it leaves the evaporator -

    so the passenger side -
    getting full liquid freon - gets cold -

    the driver side only getting partial liquid - and partial gaseous freon -
    won't get as cold -
    --------------------------------
    try this -
    connect your gauge set -
    turn passenger side temp off -
    set temp to 60*
    set fan to medium speed -
    select center vents only -
    insert an accurate thermometer in the middle vent -
    run the engine at a high idle - 1500 rpm -

    list the ambient air temp -
    the duct discharge air temp -
    and BOTH the high and low pressure readings -

    with an 80* ambient temp -
    you should easily get between 37 and 40 duct temp -

  14. #13
    Ranger's Avatar
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    Re: A/C problem 2001 sts

    Also check the Evaporator inlet and outlet pipes at the firewall. They should both be the same temperature (cold). You can check it by hand, but an IR thermometer would be even better.

  15. #14
    vinndiesel is offline Cadillac Owners Member
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    Thanks basscatt ill try this on Monday when I get back to the shop ill get the readings and report back with info ... Thanks guys for ur help so far

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