| Original message
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Replies:
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| cneiner
 |  "Re(1):Walk-in Freezer"
, posted Fri 25 Mar 17:35  
Low voltage cause compressors to run hot. Check the supply voltage and the amp draw. Check the compressor discharge temperature. Discharge temperature should be at leaste be below 230°. CHECK THE OIL LEVEL.
Check superheat at the compressor. Compressor return gas should not exceed 65°.
If the bubbling in the site glass is downstream of the filter drier, check pressure drop across the drier.
Partially plugged driers can cause low refrigerant flow rates wich lead to excessive evaporator superheats. Compressors are refrigerant cooled and low refrigerant flow rates cause them to run hot. Additional flow restriction can be caused by an EPR. A deep freezer should run well below zero degrees so the suction line at the compressor should be ice cold.
Removing a little refrigerant while the site glass is full, will not generally lower the pressure at the compressor unless the system is critically charged.
If it has a TXV make sure the evaporator superheat is good. Make sure you check it upstream an existing EPR.
R&D Hussmann
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| mrfixit
| "Re(1):Walk-in Freezer" , posted Sat 15 May 10:35
is it warm in the walkin at first? this is a normal pressure if it is . you need to charge it to a full sight glass first and then you nedd to adjust the superheat to 4-7 degrees. now close off the suction valve a little so your compressor dont get hot and go off on internal overload,when it reaches 30 degrees turn the suction valve full open. if you cant achieve this temp with the above being done look at the folling; if the pressures are almost equal you have a valve bad, change the valve plate to test this before you change it shut off the receiver valve to make it pump down if it wont go into a vacuum the valve plate needs replaced.if you replace ,after you take the plate off look inside the cylinder , bump start the compressor to see if both pistons are moving if not it broke a rod and you need a new compressor.
rick kirk
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| Xenos
Webmaster 
| "Re(1):Walk-in Freezer" , posted Thu 15 Apr 20:42
I don’t work in refrigeration so I don’t know what your pressures should be however I understand refrigerants and pressures so lets talk this out.
Both your pressure are dependent on load if the load is high your pressures will be high and or visa versa.
So lets say your load is X btu’s and this creates a saturation pressure of 30lbs. now you can add or remove refrigerant and as long as you don’t starve or saturate the evaporator too much, the pressure will remain at 30Lbs since this is you load or refrigerant saturation point. This is where superheat and sub cooling come into play. IF your system is locking up my first thought is what’s the super heat. Why? My first though is it’s overheating. Secondly would be is the condenser clean since if we can’t reject the heat we can’t pick it up.
Now is 200 head low or high on this kind of system I would expect it to be high.
Xenos.
The best way to escape a problem is to solve it.
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| | RTech
| "Re(3):Walk-in Freezer" , posted Sun 29 Aug 15:19
Sorry for late response, just turned on to this site.This may help in future situations.R404a is a blend refrigerant,adding or removing refrigerant not recommended due to fractionation.(you dont know what component of this blend leaked out).Rule of thumb,if you suspect 50%or more loss,recover,repair leak,new drier, evacuate,to a minimum of 500 microns.(p.o.e. oil is a siph for moisture).Install new refrigerant charge,(preferably R507 refrigerant,does not fractionate,) in liquid state only.I would not attempt to clear sight glass, until box temp.drops to at least +20f, and do not attempt to set txv superheat(4-8 dgrees)until box reaches design temp.NO compressor superheat was given,based on the fact compressor was cycling on its internal overload i would guess compressor s.h was high, and you were not getting adequate suction gas temp.back to the compressor for cooling.For most compressors,(recips.)a minimum of 20-30dgrees is adequate to prevent liquid slugging, and 60degrees maximum return gas temp. for cooling.No condenser style was given,assuming indoor air-cooled, with fan coil evap., running 200#h.p.(90 degrees cond.temp.)and 30# suction(0 degree evap. temp.)with no other info. my first guess, and I mean Guess, would be that system is short of refrigerant, causing high return gas temp. to compressor,causing o/l trip.It is crutial when diagnosing refrigeration problems that you know your refrigerants properties, Glides if any,type of condenser. entering and leaving temps.,liquid line press./temps.,evap. ent. and leaving temps., and suction temps.Thier are a ton of differant types of refrigeration systems,and applicaitions out ther the more info. you can supply the better.
Always be thorough!
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| | Xenos
Webmaster
| "Re(4):Walk-in Freezer" , posted Sun 29 Aug 18:53
An answer like that does not have a time limit.
Xenos.
The best way to escape a problem is to solve it.
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| | kodiak
| "Re(3):Walk-in Freezer" , posted Mon 31 May 22:34
Is the sightglass before or after the filter drier?
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| | Xenos
Webmaster
| "Re(3):Walk-in Freezer" , posted Fri 16 Apr 07:59
Is that head pressure high or low? I it’s low it could be the valves however I it’s high I would assume it’s load.
Xenos.
The best way to escape a problem is to solve it.
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