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Possible Inefficient compressor check

Hello all
I have a refrigeration question.
I am working on a True two door reach-in cooler. It is not maintaining temperature at 40°F
Running at about 52°F.
The compressor is running but not very hot to the touch. The airflow over the condenser coil is Luke warm and my condenser split is about 5°F.
The metering device is a cap tube system.
The compressor is fracture at 1/3 HP
I do feel the compressor has bad valves and is Inefficient.
There are no service ports to connect my gauges, without service ports or anyway to pump it down, is there any way to test my compressor.
Thanks Steve


    JUGHNE Member Posts: 10,914
    It could simply be almost out of gas.
    I would put a piercing tap on the suction and see if it had any charge.
    If some shown add charge to see if it is actually compressing.

    Sounds like an economy unit, might be time to change.
    How old is it? What gas?
  • sraburne
    sraburne Member Posts: 16
    Reach-in is 10 plus years old. -R134A
    Customer does not want me to put piercing taps on. He is probably going to replace it. I’m just curious if there’s a way to check the compressor, without put my gauges on
    EBEBRATT-Ed Member Posts: 14,552
    edited March 2019
    Put an amprobe on the compressor wires. If it's single phase which it must be put the amprobe on the common wire.

    For example if the compressor is rated at 10 amps and it's drawing 5amps it aint working hard.

    Check the suction line temp If you need 40 degrees in the box you suction temp would have to be 10-15 deg lower so suction temp would be 25-30 deg.

    As @JUGHNE mentioned you probably low on gas. Leak test it

    That's as far as you can go without gages on it
    JUGHNE Member Posts: 10,914
    For the future FWIW:
    The small bolt-on type piercing saddle taps are cheap and quick.
    (and usually an eventual leaker...but for temp purposes OK)
    That would give you an indication of operation.
    If the equipment was worth fixing then you could solder in some conventional type taps.
  • pecmsg
    pecmsg Member Posts: 4,390
    Tap O Lines are only for gaining Access to the sealed system and Must be removed and replaced with a Schrader after the refrigerant has been properly recovered!
    JUGHNE Member Posts: 10,914
    In my early days of attempted appliance repair, I would see these on sealed systems. They made the leak easy to find as you were looking at it.
    Many of these were put on as most assumed adding gas would fix anything. Usually the problem was plugged coils or failed fans. And eventually a leak. ;)
  • Leonard
    Leonard Member Posts: 903
    edited March 2019
    Did the same thing when I first started doing window A/C units.
    I was green, was suscessfully recharging cars with R-12 and gauges. Figured I'ld expand into window A/Cs

    Customer complaint was Warm air out the evaporator, added and removed R22, no improvement. Eventually "discovered" that a thin "minor" layer of dust on condensor fins was killing air flow so much that R22 couldn't cool and condense enough. Found that since back in the day window A/C systems were all brazed/welded they never leaked , unless you put a screw thru the tubing.

    Eventually did a good side business just picking up old units washing the coils (Clorox and Tide) , re-painting and reselling during heat waves when stores sold out.
  • sraburne
    sraburne Member Posts: 16
    Thank you all for the help.
    I understand using a piercing saddle taps, and yes it's a guaranteed leak in my experience. I always will braze in a proper service port after a repair is done.
    But, even after i do put taps on. Their are no king valve to pump down the system to check the compressor valve, if they are marginally bad it may not show on the gauges . If the valve are shot i will see it on my gauges, yes.
    I hate to make a repair and find out the compressor has 1 leg in the grave.
  • pecmsg
    pecmsg Member Posts: 4,390
    recover the charge
    Install a proper Schrader valve
    Install a Sporlin 032CAP-T drier
    Recharge to factory specs and take it from there!
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,645
    Cap tube systems are extremely sensitive to charge. Most only hold a few oz. of charge anyhow. There is no point if the customer won't let you actually diagnose it. I pierce, recover, then braze in a Hi and Lo Schrader valves.
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!