It’s a complete brand new system, first charge and had issues. Ac replaced all lines and hoses, condenser, evaporator, dryer, and compressor. Replaced low and high side switch. Would short cycle, bypassed and would see low side drop to nothing, and high side just climb. I have new liquid line with orfice tube coming. Will flush condenser and evap to remove any oil. And I’ll drain compressor, measure and see. Was going to try to just use air to push any oil out to kinda try to get oil reading in case there was to much oil.
A/C issues
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It’s a complete brand new system, first charge and had issues. Ac replaced all lines and hoses, condenser, evaporator, dryer, and compressor. Replaced low and high side switch. Would short cycle, bypassed and would see low side drop to nothing, and high side just climb. I have new liquid line with orfice tube coming. Will flush condenser and evap to remove any oil. And I’ll drain compressor, measure and see. Was going to try to just use air to push any oil out to kinda try to get oil reading in case there was to much oil.
I verified as I had a doubt about the 40 dollar gauges. Tried a better brand and same pressures. I pulled liquid line and orfice tube was crushed it looked like. So I’m hoping it’s that or the dryer that I’ll replace. I’ll check to make sure I have no blockages on Evap/condensor with air. There is no debris since it’s a new system and just trying to clean out oil to get a measurement. Will try air first to kinda reclaim oil, then a flush if the air doesn’t do anything
Sounds like you found the problem.
Sounds like you found the problem.
Hope this turns out to be right, but when you evacuate and charge it back up again, just think through the process very carefully and make sure there's no opportunity for introducing any air. Some of your described behavior lines up with that of a system with "noncondensibles", the most frequent we run into being air or nitrogen, and occasionally volatile oils used in manufacturing (more on that later). It takes up space in the heat exchanger (condenser), making it effectively too small to reject the heat and spiking the high side pressure. An easy way to screen for this is to let it sit for a while until the system equalizes and reaches ambient temperature, and then check the pressure. Both sides should be equal and line up within a couple degrees of the saturation pressure associated with the ambient temperature for R134a (you're looking for the pressure at which ambient lines up with the boiling point). Danfoss Ref Tools or Bitzer Refrigerant Ruler are both good, ad-free smartphone apps that will easily show you that association.
I've read through the thread pretty thoroughly and it sounds like you're doing everything right, just wanted to put this out there in case there's something not coming through in the text.
RE: volatile oils - I remember one time we were having a heck of a time pulling systems down to vacuum before charge and it turned out that the condenser shop was using mineral spirits in their process and they just had to be exposed to the vacuum pump for a really long time to evaporate. I don't recall if it would pull down and then climb back up as if there was a leak, or if it would just not pull down. But if you have the time at the shop, it might be worth vac'ing, then sitting overnight and vac'ing some more before charging it.
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Just for my selfish educational desires, what behavior that you observed in the OP's posts indicated noncondensibles in the system? I've been really struggling to gain diagnostic knowledge with A/C systems, and this is a good one to explore.
Thanks for that diagnostic check idea, and thanks for the app reference - very useful! I just downloaded the first one you listed.
I bet that one was a head-scratcher! I would guess it pulled down and was held there for a while with the pump running (but not long enough to boil off all the mineral spirits), and then the pump was shut off. As the mineral spirits started boiling off due to being in a high vacuum, the expansion from liquid to gas would cause the vacuum to fall (pressure was rising from the expansion). Speculating further, I'm guessing the techs probably reacted by assuming a leak, investigated, but couldn't find one. Then the engineers were consulted, and an investigation was started with a "what if..." brainstorming session, and eventually, someone put 2 and 2 together and got 4. The first 2 being mineral spirits were found. The second 2 being mineral spirits take a while to boil off (or the quantity of mineral spirits was high). And 4 being mineral spirits boiling caused the false leak.
high discharge/condenser pressure and low suction pressure. Basically the non-condensible takes up space in the condenser, leaving less area usable for heat transfer, and the temperature has to be higher to get enough temperature difference vs ambient to reject the heat.
Most often you notice the elevated high pressure before it's fully charged and think it's done and stop charging early, but as expected with an undercharged system, the low side pressure is still low but not doing much cooling since there's not enough liquid going through the phase change to absorb much heat. The fact that he's got the full 20oz in it makes me like your crushed orifice tube as the problem more than this non-condensibles theory, but I figured it was worth posting in case he still has the problem or future searchers find this thread and don't have any reason to suspect solid debris or component damage.
No problem! I used the Bitzer one for years but found out some of my colleagues were using the Danfoss and I've switched to it, as the interface just feels better designed for switching back and forth between refrigerants and toggling different options, etc. Plus I don't mind the red on black color scheme.
I've always been more of the "how it works" guy than "how to build it", but the build-it guy sat across the aisle from me so I got to hear about it second hand and what you describe is pretty much how it went. The vacuum and leak check process usually took about 4 hours but would not meet the 500 micron (~0.7 millibar) threshold required before charging. They'd assume a leak, pressurize with helium and run around looking for leaks with a sniffer and come up empty. Put it on vac again, still wouldn't pull down. The process would go on for days, and it would seem completely random. I don't remember exactly what was happening but they did figure out that somehow a small minority of condenser coils wound up making it to final assembly with a higher amount of liquid mineral spirits inside and would shut the whole line down, and most importantly they figured out how to make it stop.
I truly appreciate the detailed posts, really helps me in the long run. I’ll pull vacuum longer let it sit and pull vacuum again. Should I use a flush solvent in evap and condenser if there are oils? Parts come weds it looks like so I just want to do as much prep work as I can
Can you post a picture of the FOT? Since you essentially replaced the entire system, and seemed to follow the right charge procedure, I think that's the likely offender. It won't hurt to flush using the proper solvent and compressed air, but it may not be necessary. Regarding PAG oil levels, I'd follow the FSM for that. I haven't worked on my TJ's A/C system, and I haven't read that section of the manual, but they're usually pretty specific about how to determine the right amount of oil in the system.
In the racing world, you have to be both. In my current civil engineering leadership role, I preach that you can't design something unless you understand how it will be built, and I strongly encourage field visits for inexperienced engineers.
I certainly imagine that being the case. Having worked for organizations ranging from 250 to 60,000 I've seen the way the boundaries around what's "my job" get more blurry as the organization gets smaller.
I definitely do more of both now, but at the time this issue occurred, I was in the 60k company with sharper boundaries and the guy that solved the problem had previously set up that condenser shop and actually had his name on a patent for a new process they'd utilized in that area, so he was naturally going to have a leg up on pretty much anybody else that could have tackled it.
If the low side is pulling towards vacuum and the high side is going way up I'd definitely be thinking about a low side restriction. That is what happens when the compressor sucks all the refrigerant into the high side and it has nowhere to go. As said earlier it should be hot or warm up to the restriction and if not cold it will be cool after it.
I’ll post one, was snapped in two looks like upon install of factory, I’ll be home shortly. It said 8oz so that’s what I followed. So I’m blowing out evap; condenser, and I’ll drain ac compressor from the drain port. Factory fill for compressor was 6.1 oz told me to drain and then put in condenser and dryer. So this time I’ll just place in condenser and I have an oil injection tool that I’ll use to add slowly. Pag 100 oil is what mine calls for
I’m leaning toward the orfice tube on this one, we’ll see if that’s the issue on weds
Keep in mind that using a compressed gas to remove a liquid from a complex container like those doesn't work very well because the gas follows the path of least resistance around the liquid. I suggest you try draining it using gravity, too.