I'm not sure if I'm looking for advice or reassurance on setting my AC pressure. I have been reading through this forum for over a year now, but this will be my first actual post. I will try and not be too wordy, but I know how hard it is to answer a question without all the information. I have experience in automotive AC, but not all that experience is the same.
I have two air conditioners on my house. For the last few years the evaporator core on the downstairs unit has been leaking, and it has progressively gotten worse. Just last summer I had to have 3lbs of R22 added in a 2.5 ton unit. I had to pay $/lb for the R22 and I decided it was about time I fixed it. I spent an entire day last month like a Morlock in my crawlspace changing out the evaporator core. I installed a Bryant core which I purchased in the box. I had to change out the 410 expansion valve for an R22 expansion valve.
It was still chilly in March, so I elected not to try and get the pressures perfect while it was not warm enough to set it properly anyway. I evacuated the system, and pressurzied it. I am using EF-22a. I know, nobody likes it because it's not on the SNAP list and it's flammable. However, the only way I could get a decent price on R22 was to buy 30lbs of it at a cost of $, and I really didn't want to make that kind of investment when I would be stuck with at least 22lbs of R22 that I didn't need when I was done.
My question has to do with the pressure. Cars are easy; set the suction side to just above freezing and make sure the liquid side doesn't go too high. Today was the first day it got reasonably warm. When I got home from work it was 81 degrees outside, and 77 degrees inside the house. According to the P-T chart, it should be about 65 psi on the suction side to be at 40 degrees. I set that for an initial target. I had just a little too much gas in it initially, so I bled it out slowly. Initially I had it at about 80 psi on the suction side, and 160 psi on the liquid side. When I hit a sustained 70 psi on the suction side, it stopped cooling all together. I brought the gas pressure back to where it was a sustained 78 psi on the suction side, and 160 psi on the liquid side, and it got nice and cold again. I let it run for awhile, and it started getting really cold. I have been letting it run for a few hours now, and it is coming out of the duct at 48 degrees. I checked the suction line coming out of the evaporator, and it is cold, but definitely above freezing. I'm not sure why I am not getting the temperature I would expect with the P-T chart. Am I reading it wrong, or measuring it wrong?
Thank you for your help,
Kurt
I have two air conditioners on my house. For the last few years the evaporator core on the downstairs unit has been leaking, and it has progressively gotten worse. Just last summer I had to have 3lbs of R22 added in a 2.5 ton unit. I had to pay $/lb for the R22 and I decided it was about time I fixed it. I spent an entire day last month like a Morlock in my crawlspace changing out the evaporator core. I installed a Bryant core which I purchased in the box. I had to change out the 410 expansion valve for an R22 expansion valve.
It was still chilly in March, so I elected not to try and get the pressures perfect while it was not warm enough to set it properly anyway. I evacuated the system, and pressurzied it. I am using EF-22a. I know, nobody likes it because it's not on the SNAP list and it's flammable. However, the only way I could get a decent price on R22 was to buy 30lbs of it at a cost of $, and I really didn't want to make that kind of investment when I would be stuck with at least 22lbs of R22 that I didn't need when I was done.
My question has to do with the pressure. Cars are easy; set the suction side to just above freezing and make sure the liquid side doesn't go too high. Today was the first day it got reasonably warm. When I got home from work it was 81 degrees outside, and 77 degrees inside the house. According to the P-T chart, it should be about 65 psi on the suction side to be at 40 degrees. I set that for an initial target. I had just a little too much gas in it initially, so I bled it out slowly. Initially I had it at about 80 psi on the suction side, and 160 psi on the liquid side. When I hit a sustained 70 psi on the suction side, it stopped cooling all together. I brought the gas pressure back to where it was a sustained 78 psi on the suction side, and 160 psi on the liquid side, and it got nice and cold again. I let it run for awhile, and it started getting really cold. I have been letting it run for a few hours now, and it is coming out of the duct at 48 degrees. I checked the suction line coming out of the evaporator, and it is cold, but definitely above freezing. I'm not sure why I am not getting the temperature I would expect with the P-T chart. Am I reading it wrong, or measuring it wrong?
Thank you for your help,
Kurt
