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Thread: A/C overcharged

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    A/C overcharged

    I posted on here a while ago about fixing my A/C. Basically I spent a bunch of time and money thinking I knew what the problem was and ended up doing nothing because I couldnÂ’t get the compressor to engage. Well, with the weather cooling off a bit, I noticed when I hit the defrost button on a foggy morning that the snowflake button turned on and my car started making more noise. Lo and behold the compressor was engaged and spinning for about a minute and cold air was blowing. I went home and the next time it was cool out, I put a pressure gauge (not an A/c manifold gauge, just one that comes with a refrigerant can) on the low side and turned the A/C on to see the reading. It was still reading high with the compressor engaged.

    The last time my A/C was touched was by a body shop when I hit a dead deer on the highway and insurance covered everything. I think they may have waaay overfilled it because the Mirage is a small car. Maybe they couldnÂ’t getthe info on it so they filled with the same amount a similar sized car uses? I donÂ’t know how shops work on that level so I am not sure. My A/C has not worked since late summer of 2020. I plan to get some of the refrigerant removed to see if it all still works without the extra pressure.

    What do I need to check to know if my compressor is damaged? It is noisy when it engages, like it always has been, but are there any sounds in particular I should be wary of? I donÂ’t want to screw up my whole system if it is trashed.



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    I want to add that it makes my RPMs jump by about 300 when the compressor engages. I am wondering if my belt needs tightened or if running the compressor could snap my belt if something is bad in the clutch or bearing.

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    Compressor when engaged will make a noise. First it will make a click sound which indicates the compressor clutch has magnetized and is locked/engaged. Then you will hear the compressor running like a low humming sound accompanied with the engine revving. If you hear a high-pitched screeching noise then the compressor is problematic. SEARCH GOOGLE FOR COMPRESSOR BLACK DEATH.

    I have not noticed how much rpm the compressor consumes but it is noticeable. Even when driving and when the compressor comes on, you will feel a lull in the engine.

    The "snowflake" button will be your A/C cold activate button. It will be the switch which turns on the compressor. NOTE: You can still have A/C blower motor engage with just ambient air by not turning on the "snowflake" button. I am just wondering why your A/C button NEVER turned ON before. I have worked with a couple of A/C systems and this will usually turn on. I have a 2014 mirage and it is a straightforward HVAC (Heating-Ventilation-Air Conditioning) system with not much components. Overcharging the system will still turn on the "snowflake" button but you will not get the desirable temperature. I believe this is an electrical wiring issue.

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    It is possible to have the green light turned ON for that "snowflake" button even if the compressor is not running. All that light means is the compressor has been given the go-signal to operate. When it meets the required conditions (pressure switches) then the compressor will magnetize and kick-in. If that "snowflake" button NEVER turns GREEN, then that problem is electrical.

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    Quote Originally Posted by danbal View Post
    Compressor when engaged will make a noise. First it will make a click sound which indicates the compressor clutch has magnetized and is locked/engaged. Then you will hear the compressor running like a low humming sound accompanied with the engine revving. If you hear a high-pitched screeching noise then the compressor is problematic. SEARCH GOOGLE FOR COMPRESSOR BLACK DEATH.

    I have not noticed how much rpm the compressor consumes but it is noticeable. Even when driving and when the compressor comes on, you will feel a lull in the engine.

    The "snowflake" button will be your A/C cold activate button. It will be the switch which turns on the compressor. NOTE: You can still have A/C blower motor engage with just ambient air by not turning on the "snowflake" button. I am just wondering why your A/C button NEVER turned ON before. I have worked with a couple of A/C systems and this will usually turn on. I have a 2014 mirage and it is a straightforward HVAC (Heating-Ventilation-Air Conditioning) system with not much components. Overcharging the system will still turn on the "snowflake" button but you will not get the desirable temperature. I believe this is an electrical wiring issue.
    From what I understand the high pressure switch keeps the clutch from engaging when the refrigerant pressure is too high. But when it is cool enough outside in the mornings, the refrigerant contracts enough for the pressure to decrease and deactivate the high pressure switch, allowing the system to engage the clutch.

    Ever since the A/C quit blowing cold two years ago I have not turned it on because I didn’t want to cause “black death”. I also don’t use the auto climate control and just do everything manually when I use the heat or the ambient temp blower. The only reason I realized it was on was because my husband had driven it earlier that day.

    The snowflake indicator did show before but I never heard the compressor working so I figured something was wrong. But IÂ’m at the point now where IÂ’m either going to fix it or IÂ’m going to go buy a shorter belt and accept my fate. IÂ’m half tempted to get the system evacuated so I can take the compressor apart and find our for sure if itÂ’s screwed.

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    Quote Originally Posted by danbal View Post
    It is possible to have the green light turned ON for that "snowflake" button even if the compressor is not running. All that light means is the compressor has been given the go-signal to operate. When it meets the required conditions (pressure switches) then the compressor will magnetize and kick-in. If that "snowflake" button NEVER turns GREEN, then that problem is electrical.
    My Mirage doesn’t have any colors on the climate control screen, even when I first purchased it at 30k miles and everything was stock it didn’t have any colored lights. That seems like a nice feature.

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    Okay. Your recent statement makes more sense. So the system being overcharged would probably be the more probable cause.

    There are usually THREE switched for basic HVAC systems:
    1) High pressure - Low refrigerant switch (Hi-Lo switch)
    2) High pressure switch (this is the one you mentioned)
    3) Condenser fan switch

    You are correct that your clutch only kicks in during cold weather. Since the R134a A/C gas is sensitive to temperature outside. On cold mornings, the R134a gas pressure is just low enough to have the compressor kick-in. But once it gets hotter like mid-day, R134a gas will then expand resulting to higher pressure in your system. Thus triggering the hi-side pressure switch and turning OFF the compressor. I say that your A/C is overcharged by atleast twice the needed amount. It takes PLENTY of gas pressure to TRIGGER that hi-side pressure switch. I have overcharged HVAC systems by a few grams but it will still work.

    You do not have to do a full evacuation of your system. Depends on the workshop you visit. You can just tell the mechanic to evacuate "some" gas because it was overcharged. Also, it is advised to turn on your A/C compressor once a week to get the oil lubrication to the system. Specifically the o-ring and seals. You mentioned not turning on the A/C for two years sounds like trouble to me.

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    Quote Originally Posted by Princess_Bishi View Post
    My Mirage doesn’t have any colors on the climate control screen, even when I first purchased it at 30k miles and everything was stock it didn’t have any colored lights. That seems like a nice feature.
    Sorry, I failed to mention my mirage is 2014 ES model and yours might be a newer model. So my HVAC console would look very different to your HVAC console. Your one would be a more sophisticated climate control system. So ignore my GREEN light for my A/C button. It will not be there for your year model.

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    Quote Originally Posted by danbal View Post
    Okay. Your recent statement makes more sense. So the system being overcharged would probably be the more probable cause.

    There are usually THREE switched for basic HVAC systems:
    1) High pressure - Low refrigerant switch (Hi-Lo switch)
    2) High pressure switch (this is the one you mentioned)
    3) Condenser fan switch

    You are correct that your clutch only kicks in during cold weather. Since the R134a A/C gas is sensitive to temperature outside. On cold mornings, the R134a gas pressure is just low enough to have the compressor kick-in. But once it gets hotter like mid-day, R134a gas will then expand resulting to higher pressure in your system. Thus triggering the hi-side pressure switch and turning OFF the compressor. I say that your A/C is overcharged by atleast twice the needed amount. It takes PLENTY of gas pressure to TRIGGER that hi-side pressure switch. I have overcharged HVAC systems by a few grams but it will still work.

    You do not have to do a full evacuation of your system. Depends on the workshop you visit. You can just tell the mechanic to evacuate "some" gas because it was overcharged. Also, it is advised to turn on your A/C compressor once a week to get the oil lubrication to the system. Specifically the o-ring and seals. You mentioned not turning on the A/C for two years sounds like trouble to me.
    Yeah I am honestly surprised the shaft seal is still kickin and holding all that pressure in. I think the heat waves that have hit my area this summer have compounded the problem of the high pressure. So it definitely had at least a 3 month streak where it wasn’t getting any oil. It’s possible that my husband ran it before that here and there.

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    PB - I think there is a fair amount of untrue information, and a whole lot of unknown information being discussed in this thread. I say that based on having been a Task Force Team Leader of HVAC systems at the Hyundai-Kia plant. I didn't enjoy it at the time, but man, it was a tremendous learning experience.

    This post might be long, but bear with me. I'm not fully understanding your issue, and will go back as I type this and maybe understand it better. But to me, it seems like you're saying that under certain circumstances your A/C does not engage. First off, part of what I learned in the TFT was that 90% of the time, the reason behind that is from LOSS OF REFRIGERANT. The reason for the loss varies.

    You said you put a gauge on it and it was still reading high with the compressor engaged. There is a lot that is not clear with that statement. What pressure do you consider high? Did that gauge show values? I ask because maybe it just showed ranges with no values. Maybe by "high" you mean that it did not drop, like it should have done, perhaps to a green range on that gauge.

    And when you said, "engaged," does that mean you pushed the button and it showed the snowflake? Or does that mean you looked at the compressor and could tell the clutch was engaged?

    My reply above is not supposed to be accusatory, or arrogant. Sometimes I think it may read that way. But I'm not trying to be that way so please don't try to read it that way.

    I will tell you what I think. This is my opinion based on some of the things I've gathered in the thread. I think your system is probably LOW on refrigerant. If your car hit a deer, perhaps your A/C system was effected enough to induce a small leak. Or perhaps it wasn't effected at all. A body shop is not likely going to be the best at properly charging an A/C system.

    You mentioned taking it to a shop and having it evacuated. THAT IS A GOOD IDEA. Take it to an A/C repair specialist though. The only, and I mean ONLY way to know that the correct level of refrigerant is in your system is to start with a completely dry system. Evacuate, hold the vacuum to judge if it leaks (if it leaks, the vacuum will work it's way back to no vacuum), charge the system either with automated equipment that weighs it as it charges, or charge it while sitting the refrigerant can(s) on a small accurate scale (how I do it).

    2 weeks ago, I had a guy bring his Honda Oddity to my house. We were going to check it out, and if good, evacuate it and recharge it. But, his compressor was dead. Meaning, I would watch the clutch on the compressor and have him turn it on. I would see the compressor clutch engage. And when that happened, my manifold gauges wouldn't even flinch.

    And that's one more thing to keep in mind. At steady state, no A/C (compressor) running, the high side and low side pressure are equal. Perhaps this is why some people think their system is overcharged. I'm sure I thought the same before I completely understood how these systems work. I would have expected to see a "low" pressure when connected to the low side. But the pressure in the low side is only "low" when the compressor is working. When the compressor engages (assuming everything in the system is working correctly), from steady-state the high side goes higher, and the low side goes lower. Let's say the A/C system is running and you have the hood up. If you shut off the engine, you will likely hear some hissing for maybe 10 seconds I guess. That hissing is the is the system pressure balancing (low side getting higher, the high side getting lower, until they are equal).

    Think of the pressure in the system to act like a seesaw. With the engine idling but the compressor off, the seesaw is completely level. With the engine still idling, but press the A/C button and the compressor starts working, the seesaw tips one way and stays there. One side goes low, and one side goes high, and stays there. Every time that compressor stops, the seesaw levels out.


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