freezing suction line

[hodgy911]

have a carrier roof top suction presuuer fine and head pressure fine airflow good to suction line out of evap frost back within two mins of running

[goshen]

Hi :
what ***** are u using ?
what are the pressures?
superheat?
subcooling?
some info could help!

[ironmen]

If the system is using TXV or EEV check the subcooling if its using fix bore metering check the superheat.This two information tells it all.

[benijoseph]

Less air flow in evp or excess gas.

Regds

[hvacrmedic]

have a carrier roof top suction presuuer fine and head pressure fine airflow good to suction line out of evap frost back within two mins of running

If it's frosting back, then then the suction pressure isn't fine. Frosting back within two minutes would also pretty much require low superheat. If airflow seemed fine, then you should check it again, because it may not be fine. Also look for a restriction of one or more of the orifices.

[kkboy]

Is the indoor fan belt driven.

[jakabus]

Was it a humid day? All I can think of is frost lines... dont worry about them. they do not gauge anything no matter how serious they look

[Old cooler]

Does it stay frosted, all the time the compressor is running?

[Crash Pilot]

Definately need more info.
Like said before above I would check superheat.
Need to know if it flooding back or Frosting.
Best way I describe this to apprentices that annoy me is.

Stick your tounge on the suction pipe. If you can get it off then its frosting back. If you cant then it is flooding back.

Frosting -Low gas / Restriction metering device.

Flooding Back -Low Air flow /overcharge/ Metering device problem.

Biggest problem with package unit is airflow. Need to adjust pullys based on duct static and rated airflow.

[frank]

Frosting of the suction line can also be attributed to a low indoor heat source on an A/C install