A/C overcharge will it lockup the compressor and break the belt ?
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Thread: A/C overcharge will it lockup the compressor and break the belt ?

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    Default A/C overcharge will it lockup the compressor and break the belt ?

    Hi Brains Trust
    On another thread an AFer has broken an auxilary drive belt, twice, and destroyed the harmonic balancer also. Snapped the belts too, not shredded it.
    Does anyone have experience of having an air conditioning system overcharged and causing a problem like this or any problem.
    I do believe it is possible in theory but I have never seen it happen. On this car the A/C may have been inexpertly topped up previously.
    Cheers Jaahn

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    Last edited by jaahn; 19th February 2018 at 07:50 PM.

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    1000+ Posts robmac's Avatar
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    Overcharging can certainly break reed valves. In fact I've broken them myself with "liquid slugging" when I was lazy using "hi side charging" with liquid.

    And with a little mental extrapolation of the broken valves in a variable volume swash plate compressor it's not hard to visualize internal grid lock of components occurring.

    When the compressor seizes the clutch or drive belt just slips, or that is my experience with Sanden, Sankyo and ND rotary compressors. However they are dinosaurs compared to modern variable volume compressors with poly vee belts.

    In the scenario you present, I'd hope the HP switch would act before the compressor failed.

    So I'd put the likelihood of seizing on the busted side of plausible.
    Last edited by robmac; 19th February 2018 at 07:42 PM.
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    Robmac,

    And/Or anyone else knowledgable. Do you have a bit to do with current automotive A/C?
    How can I determine the state of charge in a Xantia with R134? The sight glass is very bubbly always (but I understand this is a poor indicator with R134) and there is no cooling. The compressor comes on so the low pressure switch is recognising some pressure.
    I found someone ("convinced" them really) to top up the system until we had some cooling and a 12 degree vent temp in recirculate mode and windows closed.
    What are reasonable vent target temperatures?
    What are safe maximum high side pressures?


    Thanks,

    Farmpug

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    Quote Originally Posted by Farmpug View Post
    Robmac,

    And/Or anyone else knowledgable. Do you have a bit to do with current automotive A/C?
    How can I determine the state of charge in a Xantia with R134? The sight glass is very bubbly always (but I understand this is a poor indicator with R134) and there is no cooling. The compressor comes on so the low pressure switch is recognising some pressure.
    I found someone ("convinced" them really) to top up the system until we had some cooling and a 12 degree vent temp in recirculate mode and windows closed.
    What are reasonable vent target temperatures?
    What are safe maximum high side pressures?


    Thanks,

    Farmpug
    Sounds not good... Are you sure the mixer flap is working correctly before you go and start messing with the A/C Putting some gauges on it should soon show what is happening. If low on refrigerant I imagine the low side .... will be very low ..... Alan S used to say to watch for sweating lines etc...

    seeya,
    Shane L.
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    Quote Originally Posted by Farmpug View Post
    Robmac,

    And/Or anyone else knowledgable. Do you have a bit to do with current automotive A/C?
    How can I determine the state of charge in a Xantia with R134? The sight glass is very bubbly always (but I understand this is a poor indicator with R134) and there is no cooling. The compressor comes on so the low pressure switch is recognising some pressure.
    I found someone ("convinced" them really) to top up the system until we had some cooling and a 12 degree vent temp in recirculate mode and windows closed.
    What are reasonable vent target temperatures?
    What are safe maximum high side pressures?


    Thanks,

    Farmpug
    R134a always bubbles in the sight glass.

    The only "correct" way is to evacuate the system and charge by weight of refrigerant.

    Having said that, amount of charge becomes relatively unimportant with a receiver in the aircon circuit. Excess charge is held in the receiver.

    Cycle rate of the compressor clutch and evaporator temperature are both good indications of correct charge.

    Any experienced technician soon gains a "sixth sense" about assessing the correct charge.

    I'm reluctant to say too much more because pressures can vary depending on ambient temperature, heat load on the evaporator and the particular vehicle system.
    Mutual Respect is Contagious


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    Hi sorry to drag the thread back to the original question
    Here is the other thread about the broken belt.
    Megane II intermittent accessory belt break
    All comments ON THIS SUBJECT WELCOMED
    Thanks Rob so far !!
    Jaahn

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    Quote Originally Posted by jaahn View Post
    Hi sorry to drag the thread back to the original question
    Here is the other thread about the broken belt.
    Megane II intermittent accessory belt break
    All comments ON THIS SUBJECT WELCOMED
    Thanks Rob so far !!
    Jaahn
    Rule out the A/C by unplugging the wiring connection to the clutch (the car maybe switching the A/C on for demisting purposes etc... even though you think it is off). If the problem goes away with the clutch unplugged, I'd suggest it is new compressor time. The pressure switch should shut down the system long before the pump generates the sort of load that would shred a belt!

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

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    Quote Originally Posted by robmac View Post
    R134a always bubbles in the sight glass.

    The only "correct" way is to evacuate the system and charge by weight of refrigerant.

    Having said that, amount of charge becomes relatively unimportant with a receiver in the aircon circuit. Excess charge is held in the receiver.

    Cycle rate of the compressor clutch and evaporator temperature are both good indications of correct charge.

    Any experienced technician soon gains a "sixth sense" about assessing the correct charge.

    I'm reluctant to say too much more because pressures can vary depending on ambient temperature, heat load on the evaporator and the particular vehicle system.
    I've noticed .... regardless of heat load, if it drags the suction side really low ( ie: well below 20psi) when you rev the motor. It is usually low on refrigerant. I just add enough to get the vent temps about right and the low back up a bit. It's only guesswork though .... as the ambient temperature and load on the system makes such an immense difference. In the middle of winter it's impossible. You just have to suck it dry and weigh the right charge back in.

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

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    [QUOTE=DoubleChevron;1557749]I've noticed .... regardless of heat load, if it drags the suction side really low ( ie: well below 20psi) when you rev the motor. It is usually low on refrigerant. I just add enough to get the vent temps about right and the low back up a bit. It's only guesswork though .... as the ambient temperature and load on the system makes such an immense difference. In the middle of winter it's impossible. You just have to suck it dry and weigh the right charge back in.


    Any experienced technician soon gains a "sixth sense" about assessing the correct charge.
    .....
    Mutual Respect is Contagious


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    Any experienced technician soon gains a "sixth sense" about assessing the correct charge.
    Hmmm
    Rob,
    I do not recall seeing that "in the books" as an alternative method!!
    DoubleChevron',
    If you look at the other thread you will note it did not "
    shred a belt" but actually snapped them both times ?? Perhaps a transient slug of liquid ?
    So is it correct to say the high pressure switch is also faulty if overcharge is the cause of this problem.
    Or what suggestions do you have.

    Jaahn

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    Real cars have hydraulics DoubleChevron's Avatar
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    Quote Originally Posted by jaahn View Post
    Any experienced technician soon gains a "sixth sense" about assessing the correct charge.
    Hmmm
    Rob,
    I do not recall seeing that "in the books" as an alternative method!!
    DoubleChevron',
    If you look at the other thread you will note it did not "
    shred a belt" but actually snapped them both times ?? Perhaps a transient slug of liquid ?
    So is it correct to say the high pressure switch is also faulty if overcharge is the cause of this problem.
    Or what suggestions do you have.

    Jaahn
    Yes, so unplug the compressors clutch connection and see if the belt stops snapping ... if you plug it back in and the belt snaps again ... the A/C is certainly the problem. If the compressor has been hydra-locked it'll be junk!
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

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    Default Shane's way :) :(

    Quote Originally Posted by DoubleChevron View Post
    Yes, so unplug the compressors clutch connection and see if the belt stops snapping ... if you plug it back in and the belt snaps again ... the A/C is certainly the problem. If the compressor has been hydra-locked it'll be junk!
    Hi Shane
    Is that the way you trouble shoot on the farm in Vic ? You must be knee deep in "consumables"
    I was hopeing for a more nuanced testing regime to help the poor guy in the bush in QLD.
    I was thinking the compressor will have been "stressed a lot" too.
    Jaahn
    PS the belt 'snapping' seems to be not instantaneous but happens some time after while driving. So your method is not so good really anyway.
    Last edited by jaahn; 20th February 2018 at 03:37 PM.

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    Quote Originally Posted by jaahn View Post
    Hi sorry to drag the thread back to the original question
    Here is the other thread about the broken belt.
    Megane II intermittent accessory belt break
    All comments ON THIS SUBJECT WELCOMED
    Thanks Rob so far !!
    Jaahn
    Point taken, new thread started.

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    I'd go with Jaahn's suggestion. Check the compressor with the belt off by engaging the clutch and turning the pully manually. If it is turning ok i'd discharge and vac the system and refill by weight (check at the same time if there is a leak - not holding vac).
    Don't forget the compressor oil.
    A few years ago my BIL had the Laguna AC recharged but they didn't check the oil and sure enough after a short time it seized due to lack of oil.
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    Quote Originally Posted by jaahn View Post
    Hi Shane
    Is that the way you trouble shoot on the farm in Vic ? You must be knee deep in "consumables"
    I was hopeing for a more nuanced testing regime to help the poor guy in the bush in QLD.
    I was thinking the compressor will have been "stressed a lot" too.
    Jaahn
    PS the belt 'snapping' seems to be not instantaneous but happens some time after while driving. So your method is not so good really anyway.
    That is the problem though. I cannot see a way of finding the source of the issue without isolating the problem.... You can turn the A/C compressor by hand until you die of old age .... that's nothing compared to a 200hp engine spinning it at great speed! You may even find it's the alternator dying. But how do you know with out isolating each accessory one at a time.

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

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