4 doors Freezer cabinet not cold !

[oilzee]

Hello every one , i need some help , any advice would be greatly appreciated .

I have troubleshooted a 4 doors freezer cabinet 1 1/2 Hp compressor R404A ,cap tube system .Condensing unit on top of the freezer cabinet . Discharge line from compressor go down to the drain pan ( drain pan is under the freezer cabinet and full of water , steam come out from the water ). After that the discharge line from drain pan back to the condenser .Before capillary tube it is a filter drier .

My client told me that the evaporator very fast block with ice and not cold .I get the data as below ( i use Eliwell digital temperature control to take all the temperature reading and inside the cabinet had no product )
Evap air in temp : -4°C
Evap air out temp : -
Saturated suction temp (SST) :-27°C (17psig)
Suction line temp at evap outlet : -3°C (wrap with
insulation )
Cond air in temp :+29°C
Cond air out temp :+33°C
Saturated condensing temp : No service valve
Liquid line temp at condenser output : +30°C
Evaporator coil surface : Almost full of ice

Can i say the system is less of refrigerant because the superheat or Evaporator TD too high ! At the end of troubleshooting , i realized that ,the bottom of the cabinet ( inside the cabinet ) has 2 inches high of water .

Another question is may i have a similar links that show how to refill refrigerant for cap tube system

thank you so much !

[nike123]

You need to defrost evaporator and then make measurements.
Charge is done by weight if it is known. If not, than by superheat, but only after you make system performance evaluation.

http://www.refrigeration-engineer.co...achmentid=2673

http://www.mediafire.com/?wzgtwmyhzty

[oilzee]

Hello Nike ,thank again for reply.

The system had stop for few days before i run the compressor and take the readings

[oilzee]

I have checked the functioning of digital temperature controller ( 3 signals output model )for the cabinet , It is in good condition . Defrost heating element no problem .

[nike123]

What is compressor model# and what is current?

[oilzee]

Many thanks Nike . i think i need to go back again.I try to take away those water in the cabinet and run the compressor for second time .

[oilzee]

[quote=nike123;134937]What is compressor model# and what is current?

The compressor model is Tecumseh CAJ2446Z . I forgot to take the reading of compressor running current !

[nike123]

Many thanks Nike . i think i need to go back again.I try to take away those water in the cabinet and run the compressor for second time .

OK, take also measurement of evaporator air out temperature, and if possible, temperature of one of U turn pipes at middle of condenser. Also, check that evaporator fan is working correctly and that his air flow is OK.

[oilzee]

If i use superheat method to evaluate the refrigeration system , suction line temperature at evaporator outlet shouldn't at -3°C when Saturated Suction Temperature (SST)is -27°C. Please correct me if i am wrong .

[nike123]

If i use superheat method to evaluate the refrigeration system , suction line temperature at evaporator outlet shouldn't at -3°C when Saturated Suction Temperature (SST)is -27°C. Please correct me if i am wrong .

Yes, it should not be-3, but that value depend on evaporator load and air flow at evaporator. So you first need to ensure enough condenser air flow then proper evaporator air flow, then proper load at evaporator, and only then you could evaluate low side and high side pressures and temperatures.

[oilzee]

Yes, it should not be-3, but that value depend on evaporator load and air flow at evaporator. So you first need to ensure enough condenser air flow then proper evaporator air flow, then proper load at evaporator, and only then you could evaluate low side and high side pressures and temperatures.

OK . i think the evaporator not enough air flow because coil surface almost full of ice .Maybe water inside the cabinet created so much of heat ( when i run the compressor , those water temperature is about +30°C ),due to evaporator absorb a lot of moisture !!

Evaporator fan motor is in good condition

[amitsaxena]

Dear, First defrost the system and then take the reading as -3 is because of excess frost formation happened.

[Gary]

If anything, the frozen coil would result in low superheat, but the superheat is in fact high.

At the same time, the cond dT is low (light load) and the liquid line temp is only slightly above ambient.

I would be inclined to say that the system is probably short of refrigerant.

A liquid restriction might give us similar symptoms, but we really can't tell without knowing the subcooling.