air conditioning problem

[billdozza]

Have 5 ton R-22 condensing unit that freezes up only from the suction line service valve to the compressor about 15" of suction line. Air handler outfitted with a fixed orifice piston. Pressures are 225-250 @ outdoor temp of 70 degrees and suction pressure is 57psi with an indoor temp of 72 degrees. Unit does not have accumulator. Any suggestions will b greatly appreciated.

[hvacrmedic]

You have a low evaporator load that is likely due to low indoor air flow. Your evaporator saturation temperature is below freezing.

The evaporator can run a saturated temp below freezing without icing over. The airflow across the coil raises the coil's skin temperature to a value that is higher than the saturated temperature of the refrigerant inside the coil, which in your case puts it above freezing temp. However, if even minor floodback is occuring, then a bare (uninsulated) portion of the suction line can frost over where there is little or no airflow across it.

[lana]

Hi there,

Check the air inlet and outlet temperature from the evaporator. This difference should be around 10°C. If this difference is higher say 15°C then you have lack of air flow. If this temperature difference is lower then you have heat transfer problem in the evaporator.
Also, you have to check the refrigerant amount. There is no TEV and therefore, the system is critically charged. Make sure that you charge the system according to the manufacturer's instructions.
Cheers