A/C overcharged

[Fummins]

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.

Yeah, I think this topic was brought up on a different thread
https://mirageforum.com/forum/showth...-C-not-working

The previous thread makes no mention of car being in an accident....

[7milesout]

I've been out of automotive so long now, I don't know if the refrigerant has changed or not.

On a side note, I find it somewhat annoying when people insist refrigerant be recaptured. The stuff used in our Mirages (I forget the number, 134a maybe) has nearly 0 effect on the environment. But aside from that fact, there's how many zillion cars, houses, apartments, buildings etc. And they all use refrigerant. And either they all leak, or they all will leak. So, most every molecule of refrigerant is going into the environment at some point. I don't condone it, I'm just saying, thems the facts of life.

Back on subject - I would L-O-V-E to contribute to PB's A/C working back to full power like it did from the factory. If PB were local to me, I would be willing to get it set straight, at no charge. Just bring a can.

PB - To me, it sounded like that in fact, when your compressor is fo' real engaged, that it does work. So I don't think it is a compressor issue. But it sounds like it is just not staying engaged for long, if it actually engages. Maybe long enough to clear the windows. What happens is, in the case of the seesaw, tilting all the way to one side, the target is to be 1 tiny bit above the ground. The closer to "the ground" that seesaw is, the better the system performs. However, if that seesaw touches the ground (low side sensor), the compressor is deactivated and the seesaw goes back to horizontal. My example isn't perfect, but maybe it's understandable.

If I just attach my manifold gauge or gauges (one or both) to the system with the car off, the pressure I see really doesn't convey much. The important factor is the AMOUNT of refrigerant. Can't determine that nearly accurate with just gauges.

Last year, I thought my Lexus was not blowing as cold as it did when I procured it. So I decided I was going to pull it down, vacuum it, and recharge. I sweated bullets messing with the A/C on such an expensive vehicle. It does have one thing that some cars have, but our Mirage does not. It has what's called a sight glass. I don't remember the capacity off-hand, but it's about 750 grams. That sight glass is supposed to show nothing, or almost nothing (maybe an occasional bubble) when everything is working good. As I was recharging, I got really nervous as I approached 750 grams. From memory, that sight glass stayed all cloudy / foamy until I got to about 725 - 730 grams. Then it cleared up perfectly. I put about 5% more refrigerant in it than spec'd, in case it does have a leak. So it will stay good for a longer time. I wish our Mirage had a sight glass. But that would have increased the cost of the car by $2. After good ole dealer mark up, it would have been like $50 more expensive maybe.

[7milesout]

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.

Interesting. 300 rpm sounds a bit higher than I would expect. I don't know how the ECU is programmed. But I suppose it could be possible that if one pushes the A/C button and the snowflake is displayed (I think it's an LCD screen / snowflake on the "auto" climate systems), that the ECU revs the engine a bit more based on that snowflake. If, in fact, the actual clutch engages the compressor, the compressor is a load on the engine and wouldn't rev up by 300 rpm. Maybe 100 rpm or 150 rpm (I'm guessing). But in your case, with the snowflake on and the compressor not actually working, there's no load there anticipated by the engineers' programming and it revs higher than normal. ... Perhaps ...

I seriously doubt a bad compressor would snap a belt. Bad compressors lock up and stop spinning. These belts are so strong, they just slide passed a stopped compressor pulley. That's generally when a loud screeching sound is heard. When the belt is moving but the compressor pulley is not. Bad compressors are not very common. You can look at your belt with the engine running. If it's not flapping around looking obviously too loose, it's likely good and not overly tightened.

[danbal]

Not my intention to spread misinformation. Good that you could share some knowledge on this and help myself know more as well. I am here in this forum to learn more afterall.

PB, probably best to get a manifold gauge hooked up to it to know more. Numbers on those gauges dont lie.

[7milesout]

Rereading, I notice some misunderstanding you have. I'm not trying to prove you wrong, but if you better understand the system, the better you will be at resolving the issue.

From what I understand the high pressure switch keeps the clutch from engaging when the refrigerant pressure is too high.

Not true. Remeber the seesaw. With the system off, the pressure inside the system is balanced and the low and high pressure side is equal. In fact when the system is off, the low side is higher than when running, and the high side is lower than when running (seesaw is level). So as far as the high pressure switch, it is nowhere near being activated with the system is off, so therefore the high pressure switch WILL NEVER prevent the clutch from engaging. It will however deactivate the compressor / clutch WHILE RUNNING if the pressure on the high side gets way yonder too high. Such as might happen if some kind of debris jams a line up prior to the expansion valve / fixed orifice ... probably many other ways it could get 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.

Not true. As explained above. Temperature variations on a non-running system will never effect the high pressure switch, as the high side is not at high pressure when the system is off.

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've actually never heard that term regarding HVAC system, but I don't think you could cause a compressor problem just by use. A compressor problem is likely always related to a compressor defect. Or refilling a system and not having proper lubrication for the compressor in the new charge.

I also don’t use the auto climate control and just do everything manually when I use the heat or the ambient temp blower.

I use it manually too, but because I think the AUTO function is complete crap.

The snowflake indicator did show before but I never heard the compressor working so I figured something was wrong.

Your figguring is accurate here.

But I’m at the point now where I’m either going to fix it or I’m going to go buy a shorter belt and accept my fate. I’m half tempted to get the system evacuated so I can take the compressor apart and find our for sure if it’s screwed.

Fix it? Yes.
Shorter belt? No way.
Evacuated? Yes.
Take the compressor off and/or apart? Not necessary, I believe your compressor is fine.

Do a search on facebutt. When I go in and search, it is specific to a group regarding the local that I live. I believe that's right, I don't facebutt very much. Ask for a recommendation for a fair and honest automotive A/C shop. They're out there, and local people are where to find out who they are. Facebutt = Show your face, act like a butt.