Cold but not cold enough, 325psi High side, 70psi low side

[jeffl]

I have a Rheem 3.5ton, split unit.

The tech came out earlir this year and said the high side was too high and cleaned the condenser with the water hose and he left. THey've come back again and said everything is fine. I did some work myself, just to see what I could find.

I borrowed a set of gauges and found the above psi readings. I also have a lab quality thermometer and checked the air. Coming into the evaporator is about 80 degrees (77 inside the house), leaving the evapoartor is about 62 or 63 degrees. I then checked the temp of the air leaving the condensor and it is around 124 degrees, (outside temp today is 95). The high pressure reading with freon gauges is 325psi and the low side is 70 psi. (Seems just a tad high)

The tech said that if the air coming out of the condensor is not extremely hot then the condensor is clogged and give it a good bath, by taking out the fan, running cleaner through the coils and hosing it down, put fan back.

Anyway, I've done that twice and we can never get enough cold air to keep the house below 77 until it gets almost midnight.

This unit also has a line filter/dryer in the liquid line. I found another thread where they said it could be clogged.

What would cause the higher pressure of 325psi (unit says 300 max), but more importantly, why am I not getting a colder air out of the unit?

Thanks,
Jeff

[HayZee518]

does your system use a thermal expansion valve to feed freon to the evaporator? if so the bulb should be located on the suction line on top of the tubing. the TEX valve operates on "superheat." Also what you've read about the dryer filter could also be the problem. if you are not epa rated don't open up the system!

[LazyPup]

The room air temp is 77degF and the air coming out of the evaportor is 63degF so the differential over the evaporator coil is 77 - 63 = 14degF which is correct for a properly running system.

If the differential over the evaportor was to increase beyond 14degF it would be indicating a starved evaporator.

The condensing coil has been rinsed out with water but the high side pressure is still a bit higher than it should be, which indicates the condenser coil should be properly cleaned with a foaming coil cleaner.

Based upon the pressure and temperature readings posted it appears that the system is a bit too small. Either it was initially undersized or perhaps there has been an addition to the structure that increased the load.