York Rooftop Unit: DH, DM

Re: Flashing Code 8

Flashing Code 8 = Compressor 2 Freezestat open.

If there is a call for Y2 and the FP2 input is open, the control will lockout stage 2 compressor and flash a code 8.

CHECKOUT:

1. Check Freezestat

• Remove the 6-wire (4-Black, 2-Blue) Plug from the control board.
• Check resistance across the two lower black wires.
  • Resistance = Freezestat OK
  • No Resistance = Freezestat Open
    • Open + Warm Suction Line = Bad Freezestat
    • Open + Fozen Suction Line → Step 2. Check Blower Operation

2. Check Blower Operation

• Start the unit with a call for Fan.
  • Place a jumper wire between "R" and "G" if the thermostat is not already calling for Fan.
  • The fan contactor should energize immediately.
    • Fan Contactor Does Not Engage → Step 3. Check Fan Contactor
    • Fan Contactor Engages → Step 4. Check Blower

3. Check Fan Contactor

• Check for 24VAC across the Fan Contactor coil.
  • No Power = Bad Control Board
  • Power Present + Not Engaged = Bad Fan Contactor
• Check for 230VAC across the inlet and outlet sides of the contactor.
  • Power In + No Power Out = Bad Fan Contactor

4. Check Blower

• Open the blower access panel and check blower operation and belt/belt tension.
  • No Blower Operation ⇒ Turn off power to the unit and check the motor for burnt wiring or open windings.

5. Check Filters/Coil

• Open the side compressor access panel and check the air filters and evaporator coil.​​​​​​​