Suction pipe is freezing up from heat exchenger to compressor on my walk in frezer

lack of gas in the system
when ever frost appears on an ac pipe it indicates that liquid is evaporating inside the pipe and removing heat from the surrounding air whist is moisture laden so frost appears
it normally is on the suction side of the ac compressor that is connected to the evaporator in the car as this is the low pressure pipe and the liquid gas is changing to gas as it is boiled off in the evaporator
have it tested by an accredited ac specialist shop as you could have a leak in the system

copper pipe freezing on the outside indicates that there is liquid evaporating in the space created by the suction of the compressor
the pipe normally will be insulated to stop atmospheric humidity condensing on the pipe
Suggest that you get in a technician to check gas pressures and ac operation

If the compressor is running yet the suction (larger pipe) on the compressor is not cold, or if it is frozen, you probably have a refrigerant leak and need refrigerant.

Glad to hear that cleaning the filter got us to the next step-- Congrats on the progress!
Now Tell me more about what you mean by: ..." THe compressor doesn't seem to engage."
If you can reach the compressor piping, you can tell if the compressor is 'engaging' - by noticing a drastic difference in temperature -- the outlet pipe-- usually near the top of the compressor can-- / -- and the inlet pipr -- usually further down the side or near the bottom of the compressor.
THe Discharge pipe can get VERY HOT at the top, and the Suction pipe at the lower level can get VERY COLD (likely close to freezing) at the inlet-- the lower pipe.
Be very careful!!, if the compressor has been running a few minutes-- as the outlet pipe can burn your fingers!
Anyway-- if you notice a great difference in temperature, while the compressor is running, you know that it is moving gasses thru the system-- and thus should be creating the condensing surfaces needed to cause water to be removed from the air flowing thru the coils.
Please check this, and let us know what you learn.-- then maybe we need to dig deeper--- Like where is a frost (or sweat) line appearing, -- and more about air flowing details.
Hope this was helpful- MB

Hello, if the inside fan was not running then the evaporator coil cannot absorb enough heat to vaporize the refrigerant, and the suction line will freeze including the compressor. Liquid refrigerat instead of vapor passes thru the suction line into the compressor. Lack of airflow or a low refrigerant charge is what will cause the line to freeze. In your case it was no airflow

major causes of evap.freezing dirty coil,evap fan motor or capacitor low on freon.moisture in system. first turn off cooling run fan to completely thaw unit. if possible clean coils and blower wheel. any unit running efficiently the evap coil will be at freezing or below. the key is to have enough airflow across the coil to remove the heat and humidity.its very easy to introduce air and moisture into the system. i have seen alot of techs. over the years make the same mistakes over and over again. when hooking up guages they dont purge the lines back; worst case is only to evacuate freon pull a vacume and recharge

That is most times caused by a restriction in the flow of air over the evaporator coil inside your walk-in. Restrictions will include no defrost taking place or a defective evaporator fan. If low on Freon the ice would only appear at the evaporator first and then reach the suction side of compressor once the evaporator blocks air flow completely. Defective expansion valves can show up with about the same symptom's. If you have more questions let me know and if you should see your model number of the walk-in freezer please list that number so I can get a picture of just what you are working with, Thanks, Sea Breeze

Heat exchanger was iced over, took a hair dryer and melted ice. I think defrost heater element is bad will check it this week end. I put a new computer in the frige about 3 mounths ago and will check if it has gone bad. The compressor is working fine.

The only thing I could suggest is looking at the evaporator (inside coil / cold bit) and making sure it is not frozen over reducing the airflow through the coil. If it is then put it onto a couple of defrost cycles to clear the ice build up. Not sure exactly of this type but would assume you also have a sight glass on the external unit, you can check this to see if when running the sight glass is clear (fully charged). Another check is looking at the compressor and the larger of the two lines (suction) should be cold back to the compressor (this line is normally insulated). However I would suggest your best course of action is a good refrig. techy. Hope this helps.