Heat craft walk-in cooler got me stumped

[pfinnmccool]

I got called for a walk- in not cooling properly. Was told by the owner that the unit was cooling properly then the temp started climbing. He had a company before me come in and they adjusted the TXV. After that the temp would climb a few degrees and hold for a day or two and rise again. I attempted to set it back to the factory setting so I could find the original problem but quickly realized that the spring had broke. I replaced the TXV as well as installed new liquid line and suction line driers. Pulled a good vacuum (400 microns) and held it for an hour. Then recharged the unit by sub cooling. It's a R-22 system. I have 11degrees sub cooling, suction is 35 degrees and the head is 175. Superheat remains high at 15 deg. I spoke with heatcraft tech support and was told that because of TXV bulb placement that the TXV would have to be adjusted. After all of this the compressor keeps going off on thermal overload and can't keep the system running long enough to set the Superheat. I tried to adjust the TXV hoping that it would open more, cool the compressor allowing it to run but no luck. It's a 35 deg box and a 25 deg coil I'm out of ideas. Any suggestions would be appreciated

[Dchappa21]

Could just be a bad compressor.. Have you tried to pump it down to see if the valves will hold?
Amp draw would be handy too.

Also you should never charge by subcooling if you have a receiver, just clear the sight glass and add winter charge if needed... Do you have a receiver?

What do you have for sh at the compressor?? And what's the discharge line temp??

[2sac]

First off, How could you attempt to set it back to factory setting? Never heard of a factory setting on a WIC, and without knowing what the previous company did, the statement you made doesn't make sense. Broken spring is a new one on me. How did you determine this? Suction is 35 degrees? Suction what is 35 degrees? Saturation temp? Box will never get to temp. 175 head? What's your ambient and do you have ambient controls?

[pfinnmccool]

First off, How could you attempt to set it back to factory setting? Never heard of a factory setting on a WIC, and without knowing what the previous company did, the statement you made doesn't make sense. Broken spring is a new one on me. How did you determine this? Suction is 35 degrees? Suction what is 35 degrees? Saturation temp? Box will never get to temp. 175 head? What's your ambient and do you have ambient controls?

According to sporland you can reset the TXV to factory setting by figuring out how many turns it takes to go from closed to open and then set it half way. I determined the spring was broken when I pumped down the system and took the TXV apart to inspect it. Ambient was 80 deg. No ambient controls, pump down, and it's air defrost. Sorry, I should have added more info. I have not been back to the job yet because the owner said he doesn't want to sink a lot of money into a 25 year old system and just wants us to install a new one

[baub]

175# head at 80 deg ambient, and a 35 deg SST?

I agree with replies above. Something is wrong in the compressor... likely bad valves.

[Fridge Repairer]

Sounds like a bad compressor to me. A broken TXV spring means the system would have flooded out the compressor most likely causing mechanical damage. When recharging a system with a txv you should charge it to a clear sight glass. Does your unit have a reciever and sight glass?

[2sac]

According to sporland you can reset the TXV to factory setting by figuring out how many turns it takes to go from closed to open and then set it half way. I determined the spring was broken when I pumped down the system and took the TXV apart to inspect it. Ambient was 80 deg. No ambient controls, pump down, and it's air defrost. Sorry, I should have added more info. I have not been back to the job yet because the owner said he doesn't want to sink a lot of money into a 25 year old system and just wants us to install a new one

Reason I asked is txv should be adjusted upon instalation. No factory setting per say. Example: Install a 9000 btu coil and a 1 ton valve. More than likely the valve will need to be throttled down to hit your desired SH. Too many variables in the equasion.

If he wants you to install a new one then go right ahead. Make the man happy.

[carmon]

what was the purpose of the suction scrubber.....

[markgarcia7uu]

DO YOU HAVE A HEAD MASTER?!?!?

[Tommy knocker]

Gotta assume it has a receiver, or it would never work in low ambient, and a head master, for same reason. Wouldn't scrap comp yet. Check head master.

[2sac]

Head at 175. +/- headmaster's ok. If the saturation temp is 35 degrees

suction is 35 degrees and the head is 175.

ain't gonna get to temp.
If you mean't to say suction is 35 psi and head is 175psi....well you have other issues......which are pretty obivious

[Tommy knocker]

Head at 175. +/- headmaster's ok. If the saturation temp is 35 degrees ain't gonna get to temp.
If you mean't to say suction is 35 psi and head is 175psi....well you have other issues......which are pretty obivious

Yep. Check the headmaster! Is it bypassing? Since there was no mention of sight glass and charged by subcooling I suspect it is. So why would it be?

[markgarcia7uu]

Yep. Check the headmaster! Is it bypassing? Since there was no mention of sight glass and charged by subcooling I suspect it is. So why would it be?

Sometimes it will flood the liquid line. Meaning that the condensor coil would act over sized. This happens when the restrictor piston gets stuck from bad seal or when it is over extended from "dead heading" this is caused from charging in the discharge line when breaking a vacuum.

[royd2]

did you ever check the super heat? or amp draw? does it have a head master or is it fan cycle delay?

[royd2]

or both

[Tommy knocker]

Sometimes it will flood the liquid line. Meaning that the condensor coil would act over sized. This happens when the restrictor piston gets stuck from bad seal or when it is over extended from "dead heading" this is caused from charging in the discharge line when breaking a vacuum.

Interesting. Not what I was looking for. I suspect undercharge. Not enough liquid for system when ambient drops, at night, so little to no motor cooling. Comp trips on thermal, box temp continues to rise, thermal resets, comp over heats, trips on thermal, box temp continues to rise and so on. Any ambient above 75-80 the headmaster souls not be by passing. Unless system is undercharged or headmaster is malfunctioning like you pointed out.

[pyramidhvacr]

If headmaster is bypassing hot gas in the liquid line both and compressor be very hot. Under charge system get the head psi up. What freon??? R404 need 265psi . 175psi headmaster is open pumping hot gas it to the liquid line this will pump all the oil out of compressor due to very high supper heat. Sight glass is hot too and may only see oil flowing not freon. Easy test pump down on high valve watch sight glass empty's then reopen see it top off. Dead heading is a tee pipe. I charge system 25 yrs in liquid line after vacuum. This is not dead heading how ever told you this is a (D>A>)

[Tommy knocker]

If headmaster is bypassing hot gas in the liquid line both and compressor be very hot. Under charge system get the head psi up. What freon??? R404 need 265psi . 175psi headmaster is open pumping hot gas it to the liquid line this will pump all the oil out of compressor due to very high supper heat. Sight glass is hot too and may only see oil flowing not freon. Easy test pump down on high valve watch sight glass empty's then reopen see it top off. Dead heading is a tee pipe. I charge system 25 yrs in liquid line after vacuum. This is not dead heading how ever told you this is a (D>A&gt

R22

[pyramidhvacr]

R22

If coil is 9000 btu use a 3/4 hp txv if 1 hp ok but has to close down more. Never open more than 1/4 turn from closed to start. Charge system At 35/175 under charged or txv flooding. No high Psi 80 deg head (225) Did u clean cond. first??? (WATER) not co2. Is evap. coil clean??? / Never charge a system by low side meaning 35/40/45/ first get heap psi up If compressor can not pump heat in to the coil it never start to frost after txv. The 3/8 line on the txv need to be warm not hot due to the headmaster pumping hot gas in to the coil. Must start TXV close 1/8 -1/4 turn open . Never ck supper htg at coil only at compressor. Never colder then 25/30 degs. Now some scroll must run colder. Check Coil BTU next ck compressor if side at same btu at 25 deg coil.

[Tommy knocker]

If coil is 9000 btu use a 3/4 hp txv if 1 hp ok but has to close down more. Never open more than 1/4 turn from closed to start. Charge system At 35/175 under charged or txv flooding. No high Psi 80 deg head (225) Did u clean cond. first??? (WATER) not co2. Is evap. coil clean??? / Never charge a system by low side meaning 35/40/45/ first get heap psi up If compressor can not pump heat in to the coil it never start to frost after txv. The 3/8 line on the txv need to be warm not hot due to the headmaster pumping hot gas in to the coil. Must start TXV close 1/8 -1/4 turn open . Never ck supper htg at coil only at compressor. Never colder then 25/30 degs. Now some scroll must run colder. Check Coil BTU next ck compressor if side at same btu at 25 deg coil.

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