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Ekcs
17-05-2016, 02:37 AM
M#PHHZ0070B

Hey guys, i went to a walk in cooler where the complaint was the unit was to warm.

I arrived at the unit to find the box temp to be 46f-49f,
cold control is calling for 37/39ish (hard to tell exactly)
the temp where the condenser is (above the unit in the ceiling) 90f
*****: R404a
Suc pressure: 51-56
Dis pressure: 260-274
SH: 28-30
SC: 9-12
temp across high side filter dryer 2 degree
compressor amp draw is 7.6
Evap temp was 21f according to my IR temp gun
condenser fan 2 amps
condenser coils are nice and clean.


Questions i have currently have are:

Where exactly should i be placing my probes? my SH probe was on the suction line 6 inchs away from the king valve. my SC probe was placed on the liquid line coming out of the compressor.

on the low side king valve i noticed two valves i could connect my gauges to. i took the cap off one of them noticed pressure coming out so i closed it back up. (keep in mind the king valve was still closed when the pressure is coming out) then i opened the send cap still on the same low side valve. and no pressure was coming out. Why is pressure coming out of one side when the valve is closed?

would i be wrong to say that the SH is way too high?

is it wrong to try and bring the superheat down by adding a small amount of 404?

What else should i be checking when i first approach units like this?

How can i tell if the fans are working properly? does anyone know of any good tools use for checking fans?

Any replay is more then welcome.

Thanks to all in advance.

monkey spanners
17-05-2016, 05:56 PM
M#PHHZ0070B

Questions i have currently have are:

Where exactly should i be placing my probes? my SH probe was on the suction line 6 inchs away from the king valve. my SC probe was placed on the liquid line coming out of the compressor.

on the low side king valve i noticed two valves i could connect my gauges to. i took the cap off one of them noticed pressure coming out so i closed it back up. (keep in mind the king valve was still closed when the pressure is coming out) then i opened the send cap still on the same low side valve. and no pressure was coming out. Why is pressure coming out of one side when the valve is closed?

would i be wrong to say that the SH is way too high?

is it wrong to try and bring the superheat down by adding a small amount of 404?

What else should i be checking when i first approach units like this?

How can i tell if the fans are working properly? does anyone know of any good tools use for checking fans?

Any replay is more then welcome.

Thanks to all in advance.

In refrigeration systems generally you measure the suction superheat at the evaporator outlet or right next to the TXV sensor.

Its common to have a port that is permanently open on suction (and discharge) service valves for connecting pressure switches to, that way the pressure switch can't be shut off leading to accidents or running problems.

I'd change the drier if there is a temperature drop across it, the temperature drop signifies a restriction.

I wouldn't pay too much attention to liquid line subcooling if there is a receiver in the system, just look for a full liquid line sight glass.

For the fans, check they are rotating the correct way, the blades are fitted the correct way round and are clean. Also check the coil is clean too.

Other things to look for are doors or door seals that are faulty, defrost heaters stuck on, product blocking air flow.

cadwaladr
17-05-2016, 09:41 PM
Is there any air curtains fitted? and do the users close the doors I have met so many that are just too lazy to close the door every time they exit hence air curtains help but staff hate them cut them tie them back etc.