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Discussion Starter · #1 ·
Ive got a small refrigeration system with tecumsa 1/4hp comp that always runs cool (unless i undercharge). it's a r12 comp. running r414b(hotshot). the other two nearly identical systems in the bakery run hot (comp) but work. this system ices up the evap. even after i found a leak and fixed it. i charged it using the sight glass as no info was available on correct charge (it took 2.5 lbs to get the glass full, so i probably way overcharged). there is a reciever. I replaced the TXV. still ices up evap and comp runs cold.

still a rookie...

can i check the compressor valves by running the comp without the condenser fan for a minute to see if the head will hit 450? I have been told. maybe i have to correct the charge. adjust the txv? the pressures compare to the other two systems (30/200). superheat is around 8-10. I just cant understand why the evap (clean) always ices up.

I have like 15 hours in this and still havnt fixed it yet. HEADACHE i'm sure not the first or last. :censored:
 

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Discussion Starter · #2 ·
also replaced filter dryer and does not seem to have restriction... temps on both sides of receiver/ dryer/ same. . .
 

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Discussion Starter · #4 ·
Interesting question because when i first saw the system it was short cycling on the pressure switch. It was set for high event 40 low 15. It was on and off every min. I tried adding gas didn't help and actually spiked the head p. At which point i recovered and replaced dryer and added fresh charge. But nothing i have done so far works for long before the evap ices up.

It also has a temp. Control but no defrost timer.
 

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Discussion Starter · #5 ·
The target temp of this reach-in is 50-55 deg. That should not need a defrost timer, right? It's not a pump down unit so i thought the pressure switch is just safety.
 

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What sort of reach-in has a target of 50-55 degrees?

About the only thing I can think of would be for wine chilling application....

Depending on what type of temperature control, that may be the defrost control as well.
 

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Discussion Starter · #8 ·
Yeah it is for cookies and chocolates in a bakery. So too cold and the cookies get wet or some such issue. The evap. Sure looks clean...

Maybe the single fan is not running up to rpm? I will replace the fan next.
 

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Discussion Starter · #9 ·
The temp control is johnson controls simple bulb in cabinet. Has min/med/max diff. Settings.
 

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Try taking a logical, methodical approach to troubleshooting rather than jumping around.

Check the things I told you to check, it will give you a much better idea as to what is happening.
 

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the txv should never be adjusted unless your looking to change you target superheat. check the subcooling to see if you condenser is putting out the right amount of liquid. also check you superheat to see if the TEV is working right. make sure the bulb is in the right spot. do a compressor volumetric efficiency test to see if the comp is working right.
 

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Discussion Starter · #14 ·
the txv should never be adjusted unless your looking to change you target superheat. check the subcooling to see if you condenser is putting out the right amount of liquid. also check you superheat to see if the TEV is working right. make sure the bulb is in the right spot. do a compressor volumetric efficiency test to see if the comp is working right.
THKS FOR ALL THE FEEDBACK.:thumbsup: NOW, IF I WASN'T SUCH A GENIUS AND DIDN'T ALREADY FIX IT (finally), I WOULD HAVE TO RESEARCH HOW THE HECK ONE does THAT TEST...THE SUPERHEAT IS 8.

MIRACLE OF MIRACLES IT IS WORKING NOW FOR 3 DAYS WITHOUT ICING UP. i guess i got the charge close enough and set the temp right. now all i gonna do is move the temp control's bulb to a better location.

I CALLED THE COMPANY THAT MADE THE CASE... PARISI ROYAL OF PA. THEY PUT ME WITH A TECH WHO TOLD ME THE CHARGE SHOULD BE CLOSE TO 2LBS (i put in 2.5). NOT TO WORRY MUCH ABOUT THE SIGHT-GLASS. HE ALSO WAS ABLE TO TELL ME THE HEAD PRESSURE SHOULD BE AROUND 150. So i may be slightly overcharged but i'll check the pressures again. but it is finally working. so thanks all.
 

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Discussion Starter · #15 ·
Headache finally gone

I think i may have learned that if this system run too long without cycling off, it may ice up. But it never really got very cold... Not below like 48. Probable for the overcharge.
 

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With a receiver system (assumption since you mentioned sightglass) you would need a massive overcharge to adversely affect head pressure.

Look to a dirty condenser or some other reason for elevated head pressure.
 

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IMO, overcharge sounds like it was a definite possibility as previously mentioned. I believe that you only need approximately 80% of the regular R12 charge when using R414B [Hot Shot]. Charging by sight glass alone may be hit or miss.
 
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