a/c problem

richard lampson

YOU NEED TO GET THE MODEL AND SERIAL NUMBERS OF ALL THE COMPENENTS OF THIS SYSTEM BEFORE YOU CAN BEGIN TO TROUBLE SHOOT THIS PROBLEM. ie furnace. evap coil. condenser. and while your at it get the line set diameter and length

bill andrews

a/c problem

Many of us do a/c and this is a problem I have never had before any ideas are appreciated. Installed a RUDD 4 ton a/c unit in a home. Ran good for about 2 hours and stopped making cool air. blower operates, condenser operates, pressures are equal at 110 pounds at 80 degree outdoor temperature when unit is not operating. When unit starts low side vapor line goes to 30 lbs and high side liquid line goes to 150 lbs. All lines are ok and within the parameters of the specification of manufacturer. Orafice in metering valve is .053 as required. No kinks in lines. I changed the compressor, replaced the refrigerant etc. When attempting to add R22 to get higher pressure I heated the cylinder in a tub of warm water and the pressure went up but as soon as I isolated the R22 tank and took readings of the unit I still had low vapor pressure and lower than required liquid line pressure. I tried to contact my local RUDD technical rep but he must be on vacation. Any ideas are appreciated Bill

TGO_54

AC problem

Have you checked the airflow across the coil? If the return is too small or has a restriction in in it could cause the problem you are seeing. If your duct has an internal liner check that it has not come loose and is blocking the coil when the blower is on.

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lchmb

first thought to mind

lchmb

first thought to mind

Is this a line set or did you make your own? If you made your own is it possible you left a plug in that is partially blocking the line? This would cause some wacky reading's..Just a thought

Ken_8

Hate to ask this now...

Unless the home is a "castle" in a rain forest near Guatamala, the 4-tons sounds like about two times the need.

Did you (or anyone) do a cooling load calculation?

Without exaggeration, over 90% of all A/C systems/units I see are oversized by a factor of two!



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don_46

Sounds

like you have a restriction,possible in the drier or the accurater itself,and now it overcharge.

Tony_8

sounds like

you have a restriction in your refrigerant system. At 80 you should have more than 150psi head and definitely more than 30psi suction, regardless of air flow across evap. Check your orifice, particles can plug it partially and you can't tell because it's at the normal location for phase change to take place. If it is you'll want to replace the ENTIRE liquid line as the oil will have the particles in it and you'll be back again.

john@TR

superheat?

What's your superheat? I can't tell whether you're low on charge or restricted or you have airflow issues without knowing superheat. It's a mistake to try to charge by pressures alone. Are you using a scale at all? How do you know if or how much refrig you added? No offense but you sound like you're in over your head.

Blackoakbob

Superheat

Blackoakbob

Superheat

Hi Bill,
You can check your superheat by measuring the temperature on the suction line at the service valve and compare it to the suction pressure reading converted to temperature. Some gauges have this conversion on the inner dial or use a pressure temperature chart available where you by your refrigerant. A rule of thumb is the suction pressure should not go below 55# which converted to temp gives you a 32 degree coil ( freezing) temp. Anyway , the suction pressure converted to temp and the line temp should be 20 degrees apart ie. 65# converted to temp 38 degrees and a line temp of 58 degrees.
Check your air filter and fan on the system.
Of course I'm talking about an R-22 system
Regards,

GW

AC prob

I don't dig the restriction scenario- if there was a restriction you would see higher pressure.

If it ran goor for two hours- might you have a leak? Or you plugged up the coil with ice perhaps.

You didn't tell us a whole lot- how long is this line? We can only assume that you know the basics here- like getting a good vacuum on it.

What is the air side doing?

Sounds like you don't have enough juice to me- but if you can't check the super heat, you may want to get someone to help you out.

Ken, do you live in Alaska? 4 tons is quite common.

Gary

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Dan Foley

Orifice Size

Double check the required orifice piston size. I don't know Ruud equipment off the top of my head but a .053 seems small for a 4 ton system. Most of the brands I deal with would require a .075 to a .085 for a 4 ton unit. -DF

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Jeff Lawrence_24

When I have a problem condenser, I fill out a form that's available here:

https://www.rheemote.net/

You will have to sign in and get a username and password.

The forms are located at the PTS tab and along the left side of the PTS screen. The forms are called 'Job Site Information Sheets' and are available for anything forced air. Get the AC form and fill it out (the second page). Hopefully, the answer will jump out at you. If not, ask again and give us the info on the sheet(SH, SC, delta T across indoor and outdoor coils, WB & DB temps, etc).

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clammy

a/c thoughts

Had a simalar promblem years ago low suction little high head ended up being a restriction on the orfice,pumped her down and pulled the met jet orfice out and found a piece of rubber stuck in the orfice pulled her out and vacumed her and aweay she went did ytou nirtron pressure test if not try it and also maybe unhook your line set from your indoor coil and blow nitrogren through the lines also your return should be at least 30 x 30 with 18 to 20 inch return flex and chk to make sure all damper and registers are open .I use alot of rheem stuff for many years and have yet to run into a bum unit it,s possible but double chk your lines and chk the orfice and in chraging get a good strap on digital thermotewr and go by the super heat and sub cooling good luck and peace

Mitch_4

you are low

on both sides.It is not a restriction but a leak. Recover the gas, pressure test and repair the leak, re test to "A" coil max pressure (usually 150#) if it holds for 30 minutes you're good to go. recharge and adjust to supoerheat.

If you had a restriction, your head would continue to climb, and suction drop. Because they equailze at lower than normal operating pressure, you either have insufficient gas, or you lost some. Because it ran fine for a couple of hours I would say leak.

Matt Undy

Service valve

If the liquid service valve was restricted(or the filter/drier depending on its location), the system would look low but actually be accumulating excess refrigerant in the condenser, correct?

You can check this by comparing the staic pressure(pressure once both sides have equalized and the sytem has come close to ambient) of the system just after it has been brought to the correct superheat and after it has shut down. (or just before and after it has shut down since you say you can't get the correct superheat).

Make sure you give it time to equalize and come to ambient. If the pressure on both sides is equal and is the same before and after the shut down I would suspect a restriction in the condenser before the access port such that the condenser is holding excessive amounts of refigerant.

If the static pressure goes down it is leaking (or very unlikely holding refigerant somewhere and not returning it).

Goood luck(it looks simple from the relies but there are a few subtle comments in the original post that make it look more complex, most notably not being able to get enough pressure out of the r-22 cylinder).

Matt

Frank_17

did you use nitrogen

in the lines before you brazed. if not it cound be carbon in the orriface. but it does sound low to me

val

flue

details about the flue for a Radiant heating machine

Weezbo

It sounds like a slow leak to me.

it isnt always a slow leak on what work you have done,dont lose perspective on the complete job.