Checking numbers

[daviddsims]

Got a 4 ton unit that is acting up on me. Below are my numbers:

Outdoor DB=92
Suction Pressure=82
Discharge pressure 235
Liquid line temp=110
Suction line temp=68
Indoor DB=73.5
ID WB=64
Compressor amps 10.5 out of a fla of 14
Cap tube system

A superheat of 20 is telling me that I am undercharged when my target should be about 7 degrees. Does this sound like I am on the right track?

[Techlite]

Whats the delta T across the evap

[daviddsims]

10 degrees

[Techlite]

little low on charge just need to recheck the superheat after space temp gets down to setpoint

[Techlite]

go for 12 sh

[hewitt]

What type of metering device and what is your supply and return temp.I ASSUME this is a R22 system based on pressures?

[daviddsims]

Cap tube system with 73.5 return and 64 supply. It is an r-22 system.

[Damien]

My TSH shows somewhere around 7, with the conditions you stated. I'd say you're on the right track

[newoldtech]

Is the ductwork tight?

[hewitt]

What is your cfm at return

[hvacrmedic]

You have a bad (under-pumping) compressor. High suction, low head, low amp draw, low deltaT. Adding refrigerant will only run the suction pressure up higher, and it's already way to high for those conditions on an old cap tube system.

[hewitt]

X2

[garyed]

The only way it would be undercharged is if you were sucking air from the attic across the evaporator. If the temps you measured are what are actually going across the evaporator then I agree with Hvacrmedic, you have a weak compressor.