Hello forum, I have a trouble with my upstairs R22 split AC system. I'm not sure if I have a fixed orifice or TXV as the evaporator box is sealed and I cannot peek there. I got a K-type thermometer and manifold gauge set and measured superheat being 51F and subcooling 7F. Target superheat is 19 to 20F. Also, I noticed the low pressure side fluctuates between ~55 to 65 every few minutes, high pressure side seems fluctuate less. Should I add R22 or what might be wrong here? Should I add R22? Can the pressure fluctuation be caused by a bad compressor valves? Thanks for the help, in advance.

I bought a 12,000 btu mini split system, and where I intend to install it is on an inside wall. For the room there is no viable exterior wall location. So my question is about the line sets. I will have to open up the wall in the utility room (backs up to the living room where the unit will be installed) in order to run the line sets, and I can run the condensate line down the interior wall to the crawl space under the house. Does it matter whether I run the line sets up into the attic and then down to the exterior unit, or down to the crawlspace and then up the outside wall to the exterior unit which by the way will be mounted on that outside wall rather than a pad? Without taking out a tape measure, I estimate that the run through the attic and down to the unit would be about 10 feet or so, and if I took the lines down the inside wall, through the floor joists and up the outside wall to the unit perhaps 15 feet, possibly more. The system I bought came with 15' line sets so going down would mean new lines or an extension, which would add additional costs, so the attic idea seems better right off the bat, but that leads to my second question then. Could I just leave the additional 4 or 5" of line set in the attic so I wouldn't have to cut the lines and go out and buy a flare tool? Trying to keep the cost down, already bought wall mount brackets, a Freon sniffer and a vacuum pump. Any advice would be appreciated, thanks!