Looking for insight

[elamechanical]

Arrived upon no cooling call, and found the following. 2ton r22 condenser with little to no pressure. Figured it had a leak, so I recharged the system. Checked some obvious locations and found nothing. Told the homeowner to call if they lost their cooling, otherwise id go through the system next spring. Returned today, after getting the call, and found the following. Low charge again, but my pressures were reading roughly 125 on the high and 0 on the low. So I valved off the high side, and watched the high side drop to zero and the low remain at 0. Then I valved off the condenser, and added gas through the high side and watched It come right around to the low. This confirmed no restrictions in the piping, filter drier, or evaporator. So im figuring, I have a restriction in my condenser coil. Now im scratching my head for two reasons. 1 wouldn't I have seen pressure on my low side when I valved off my high side and my high side pressure dropped to zero. In other words, if I had pressure in my liquid line wouldn't it have come around when it was pumping down. And 2 where does my refrigerant keep going? Out a compressor relief valve from the pressure getting too high because of a restriction in my coil. I don't feel my compressor valves are bad because I have a pressure differential. Any insight or opinions Is appreciated thx

[Rob_in_WV]

Did I understand correctly when you said you "valved off the high side" I took it you mean you closed the liquid line and pumped the unit down? If so you won't read any pressure because your high side gauge is reading on the side opposite where the refrigerant is accumulating, and the low side won't read either because its getting pumped into the condenser away from your low side gauge.

While its pumped down like that I'd put a small amount of refrigerant into the low side and put a lot of nitrogen pressure in with it and go over it again. (maybe as high as 300 psig) Also look for signs of oil on the outside unit.

[Chuck]

Find and fix the leak.

[elamechanical]

I will definitely find where the refrigerant is going and fix it. I just figured with the condenser running on a call for cooling, and the high side reading 150 psi, wouldn't the low side be showing pressure? (This was the case when I first arrived, and I hadn't touched anything). I figured it'd be showing something instead of 0. Even if the system is low. This indicates to me that it's pumping itself down. And like I said, I closed both service valves and ran nitrogen through my high side and it came right back around and read pressure on my low side. So, thats why I feel theres a restriction in my condenser. If there is, could the pressure build up and i lose refrigerant through a relief on the compressor? Thx

[newoldtech]

Charging up a system that was basically flat without doing a thorough leak check will burn you almost every time.

[energy star]

I would want to see some sort of pressure (not zero) on the low if the high side is 150.

[elamechanical]

The system wasn't empty or "flat" when I charged it. Originally there was roughly 25psi on the high and 0 on the low. Then when I returned there was 125 on the high. And 0 on the low. I didn't create the problem im trying to figure out the problem. Thx though.

[elamechanical]

Energy star I agree with you. However I don't, and that's why im looking for others opinions on why that may be

[carene 7]

I'm thinking BIG leak,as in sucking in air on low side.Nitro,and you will hear it.

[COOLJIM]

i would look on the low side for a largeish leak could be in line set piping , the 150 high side could well be air n a little gas ,

[elamechanical]

Yes agreed. I need to definetly put a nitrogen charge in there before I change any equipment to see if it holds. Couldn't the first time, because of how busy I was at the time. Just putting out fires. The only thing if it was a big leak I wouldn't, or at least you'd think I wouldn't, have any pressure on the high side either.

[Chuck]

The system wasn't empty or "flat" when I charged it. Originally there was roughly 25psi on the high and 0 on the low. Then when I returned there was 125 on the high. And 0 on the low. I didn't create the problem im trying to figure out the problem. Thx though.

A system with 25 high and 0 low is essentially flat. There is probably no Refrigerant in it, just air pressure.

[elamechanical]

No, it had refrigerant because when I turn the disconnect on it started to ice up. It probably is just a leak, and im looking to far into it. I though it just seemed unusual to have 125 on the high.

[Chuck]

Ok, I forgot you said it was icing.

[elamechanical]

No I didn't say it was icing, probably should have. I wasn't asking whether or not I should put refrigerant into an empty system. Im good there.

[carene 7]

Big leaks suck in lots of air and the compressor doesn't care what it compresses.Thinking seperated suction line or fitting but definately on the low side.Hope this helps.

[Rob_in_WV]

No, it had refrigerant because when I turn the disconnect on it started to ice up. It probably is just a leak, and im looking to far into it. I though it just seemed unusual to have 125 on the high.

I've found it's easier to over think a problem than under think it. We sometimes go in looking for the biggest problem that could possibly happen and it turns out to be one of the smallest. Been there and got the t-shirt.