Dectron 35hp high amperage
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  1. Dectron 35hp high amperage

    First stage compressor on this 20 year old Dectron is maxing out the rated FLA. It seamed like a typical overcharge with low discharge temp 139 deg, low superheat 7 deg/ high suction 80psi and high subcooling 21 deg low to normal head press 231 psi in the cooling only mode. 2nd stage is running normally with lower normal range suction for a dectron under low load. (55 od 76 id) I tested the txv and was able to throttle down 20 psi. To rule out an overcharge I removed 40 lbs of refrigerant which gave me still a 81 psi suction with 9 deg superheat and still 19.6 deg subcooling. sight glass is still full showing dry amperage decreased anly 2 amps now at 62 fla is 67.5. I gave the txv one turn closed for a 12 deg superheat and 191 deg discharge temp. I'm questioning air or internal discharge gas bypassing though my head pressure is low and it seams with internal bypass amperage would be lower.

    With all that being said Dectron strongly feels there is low airflow problem. Of course the evaporator is dirty & late in the day I was finding there may be internal duct issues but I feel increasing the airflow would just add to the high suction/ high amperage issue. The problem before my arrival was always high current draw until last night the motor winding protector. After running most of today it went off once from winding temp with 55 deg suction line. Another reason I question bypassing. Dectron was confident my next step should be replacing the blower pulley to max out the blower fla. Surely I would clean the evaporator ( a nightmare to access) and investigate the airflow issues. I just don't want to head to far down that direction until the amp draw is under control.

    Let me know if this rings a bell with anyone. Thanks.

  2. #2
    Join Date
    Nov 2005
    Posts
    1,347
    I hate working on those things...usually located in a pool pump room and covered with corrosion and rust. I would rule out air flow then go after the charge and or compressor. Have you tried pumping it down and seeing if the internal valves hold? What kind of compressor is it?
    I STARTED WITH NOTHING, AND I STILL HAVE MOST OF IT!

  3. A copeland 35 hp recip. I 'm going back to do a performance test. The high amps is what seams odd about valve issues.

  4. #4
    Join Date
    Dec 2009
    Location
    Fort Worth, Texas
    Posts
    150
    10-12 degree subcooling is usually normal, that being siad you are way overcharged. first thing to do is remove refrigerant till you get about 12 degrees subcooling then recheck.

  5. #5

    unit tag

    nobody ever wants to recover, but there should be tag on the system of refrigerant charge . system charge plus field charge if you have remote condenser.Cfms should be on that tag also.

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