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Discussion Starter · #1 ·
I have a Daikin McQuay package unit,
Model - RPS042DLY.
I am coming behind someone else who has been throwing diagnosis at it to no avail.
I came to the unit and it was down. Drive for supply fan was in fault for "over current". I checked the parameters of the drive because motor was just replaced and the call back situation.. I found the motor current + SF parameter was set to motors FLA amps without SF. Adjusted and cleared faults. Unit ran for 6 hours no issues. At which point I saw the duct pressure drop from 2.0in, it's setpoint, down to 1.2in but unit eventually adjusted and never shut down. An hour later, duct pressure dropped to .9, unit shut down, no faults or alarms on the unit or the drive, and restarted on its own. Did the same about 45 minutes later, and never shut down again while I was on site.
Being it a surgery center, that off time of the unit is uncharacteristic of the unit and causes issues in the space.

Unit takes care of a floor of a building, a small surgery center, mostly open with 3 ORs. Space is roughly 1500-1800 square feet.

Two circuits, four compressors that all stay running.
Space temp hovers at 69° , setpoint of 55°
10% OA
DA 52°
DA set point 51°
SAF stays around 88%
Ckt 1/2 120 / 360psi. 18 SH. 5 SC.
Schneider atv212 SAF drive

Any help is greatly appreciated.
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