Hey, I have a 2 ton train split system. This unit has been sitting for about 6 months or so. I am getting very high reading on the high side, it pegs my guage. The low side is about 30, so that make me think it is low on freon.
When I first start the system the high side read about 150 PSI, but slowly goes up, if I freon it just goes up faster, makes me think it is overcharged. It is 70 degrees outside, and a wet bulb of 69. The inside temp is 77.
I am here at the unit now I just pulled out 9 pounds of freon. factory charge is 6 pounds, and I have a bout 75 feet of line. so it was over charged! how do I go about finding the restrictions? I do have a shop vac and an air compressor. I was going to blow from 1 side and suck from the other side. do I need to worry about sucking the oil out of the compressor?
TXV or piston metering device? If it's a TXV you should be able to inspect the screen ahead of the valve. You could have it plugged with carbon from the brazing of the joints. Does it have a liquid line filter/dryer, it could be plugged.
You could put some nitrogen to it and see if you are getting good flow through the system.(seeing as you have the refrgerant out now). Put about 150 lbs pressure on liquid line and purge out through suction side, see what you get for flow. Should tell you if there is a problem in the tubes feeding the coil etc.
I am here at the unit now I just pulled out 9 pounds of freon. factory charge is 6 pounds, and I have a bout 75 feet of line. so it was over charged! how do I go about finding the restrictions? I do have a shop vac and an air compressor. I was going to blow from 1 side and suck from the other side. do I need to worry about sucking the oil out of the compressor?
Why would you pull out the gas before you found the restriction? I would have gotten a temp probe and checked where I had bad drops in the piping. You said the liquid line would eventually peg the gauge. That tells me the tx valve was blocked and I would change that. Might also have a block at the filter drier. If the system is open change both components.
Ok I did the nitrogen and purged the system, everything looks fine to me. I added 6 pounds 4 ounces of freon. Here is what I am getting: sl temp of 71.9 - ll is 78 ll has 175 psi and holding for 30 min now. Here is the kicker the suction side has only 13 psi. The temp inside is 80 degrees, wirh a wet bulb of 61.6. The ll is 67 at the handler and the sl is 64.7. the ambient air going into the air handler is 76 at the vent, the air coming out of the vet is 73. looks like I need to suck the system and check that screen huh?
once again thanks for all the good help
but when I opened the air handler it gets colder where I think that screen is, there is no frost on the outside of the air handler, but there is where is the liquid line screws into the air handler, from there to about 5 inches past that is frosty
so is the liquid liner restricted or the suction line? since it is before the air handler can I unhook the lines and just blow them out with a compressor?
Factory charge is ususally for 15 foot of line set. Add 3 oz for evey 5 foot past that so you need another 2 pounds. Don't use a compressor, get a tank of dry nitrogen or else you're blowing lots of moisture into the system. You're flashing the liquid now because it's losing all the subcool before it hits the metering device. Pump it down, remove screen, put replacement drier right before evap coil, vacuum pump to 500 microns, add 2 lbs and recheck.
Could be something you can blow out, or could be something got that has to be removed by cutting out the effected piece of cooper, or device. You have to search for the restricted area.
OK I unhooked the ll from the air handler and put nitrogen in outside, it came out put not with the force I would think. When I went to vacuum the system I thought maybe it would go faster if I took out the core on the suction side. I could not get it out it would unscrew but not come out. So I left it unscrewed in put in 400 PSI of nitrogen. Im not sure what came out but it hit my truck that was 15 feet away. lol Then of course all the nitrogen came out very fast. So Im thinking maybe there was grime or dirt behind the core causing a restriction. So I pump it down to -30 replace the core(cause I forgot to put the new one in) pump down again to 30 again held for 25 min. filled her up with 8 pounds of freon and here is what I got.
Since I did this in AC mode the big pipe is the suction side and the small pipe is the high or liquid side, right?
big pipe pres . . . . . . . . 60
big pipe temp . . . . . . . . 47.5
smaill pipe pres . . . . . . . . . 140
smaill pipe temp . . . . . . . . . .70.1
no they do not run underground. I measured exactly 8 pounds of freon going in. factory charge is 6 pounds, I add 3 ounces per 5 feet of line. I stepped the line out it was just over 50 feet. when you say hi head pressure which line is too high? and once again the system seems to be the working, or at least I'm getting 15 degree difference.
What's the temperature difference on you liquid line filter drier? You should see around 1-2 degrees. Going from those numbers and the outdoor temp those pressures seem ok. Do you have a spot to check discharge pressure or only liquid line? I wouldn't add more gas until you can get a better load. Try covering some of the condenser and see what your pressures look like.
Make sure evap is clean and filters are clean.
You have 8 degrees of subcooling and the superheat looks good. You will not get great readings until you have. 80-85 degree day.
Thats correct for the formula/method. But your charge is not as close as you think.
Good chance as doc said, your air flow is low.
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