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Rooftop Dedicated Outdoor
Air System Installation Manual
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Digital Scroll Controller Error Codes, continued.
Flash Code 8 - Compressor Contactor Fault.
• Compressor current is detected when the system controller demand signal is below 1.44VDC. The compressor contactor may have welded
contacts or the contacts may be mechanically jammed. The compressor will continue to run in this condition since the Digital Compressor
Controller cannot open the compressor contactor.
• The Digital Compressor Controller will energize the compressor contactor and vapor injection solenoid. The alarm relay contacts will close.
The unloader solenoid will remain energized causing the compressor to run unloaded as long as the system controller demand signal is
less than 1.44VDC. If the system controller demand is greater than 1.44VDC, the unloader solenoid will de-energize causing the compres-
sor to run loaded.
• The ALERT code and alarm relay output are reset when current is no longer detected while system controller demand signal is below
1.44VDC.
Flash Code 9 - Low 24VAC Supply.
• Supply voltage to the Digital Compressor Controller has dropped below 18.5VAC.
• The Digital Compressor Controller will de-energize the compressor contactor, unloader solenoid and vapor injection solenoid. The alarm
relay contacts may close if the voltage is high enough for the alarm relay to pull in.
• The ALERT code and alarm relay output are reset when the supply voltage to the Digital Compressor Controller rises above 19.5VAC.
Refrigeration Access Points
Figure 50: Refrigerant Circuit Component Locations in DOAS Chassis.
REFRIGERATION SYSTEM STARTUP