4-56 Alarm Codes, Descriptions and Corrective Actions µP-D Controller
CSR-20 & CSR-40, September 1999
Code Description Corrective Action
52 Modulation System Failure (Pretrip) • Perform a Full Pretrip Test to check modulation
(Check or Shutdown Alarm) valve operation.
• Indicates modulation valve current draw is not • Check the power module.
within limits.
• Check controller using the Microprocessor Tester.
• If alarm occurs during a Pretrip test, a
dash (-) precedes the alarm code. • Check the wiring to modulation valve using
unit wiring diagrams and a digital multimeter.
- Disconnect modulation valve leads and check
circuit resistance. Resistance should be 7.6 ohms
at 24 C (75 F).
53 Heating Current Out-of-Range (Pretrip) • Check for low supply power voltage.
(Check or Shutdown Alarm)
• Check the heater element current draw using the
• Indicates total unit current draw is not within “REFRG HEAT” test in the Refrigeration Test
acceptable limits when the unit is in Heat mode. submenu. Current draw should be 7 to 14.5
amperes at 480V. Current draw on each leg should
• If alarm occurs during a Pretrip test, a be within 0.2 amperes of each other.
dash (-) precedes the alarm code.
• Visually inspect the heater contactor and evaporator
fan contactors (EFH or EFL).
• Check the output module and related circuitry using
“REFRG HEAT” in the Refrigeration Test submenu
to place the unit in Heat. Then confirm that output
LEDs AC7 and AC12 (or AC8) are ON.
• If current draw on each leg is not within 0.2 amperes
of each other during heater current draw test, check
the current transformer. Turn unit OFF and discon-
nect power supply. Disconnect plug on current
transformer and check the resistance of each prima-
ry winding. Resistance for each winding should be
43 +/- 0.5 ohms.
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