TM  5-4520-253-13 TEST   PC   BOARD   ASSEMBLY   (CONT) Table  4-3.  PC  Board  Testing  –  Continued (1) (2) (3) Test   For/ Meter Setting (4) Probe No. 1 Component  Circuit Upper   Thermostat (Fan  Side) Heater Mode Power  Cable: Plugged HEATER-OFF- FAN   Switch: HEATER Voltage Grey Wire (23) Any   White 110 V ac Wire or Terminal Connector Any   White 110 V ac Wire or Terminal Connector Lower   Thermostat (Discharge  Side) Power Cable: Plugged HEATER-OFF- FAN   Switch: HEATER Power Cable: Plugged HEATER-OFF- FAN   Switch: HEATER Voltage Grey Wire (24) Lower   Thermostat (Discharge  Side) Any   White 110 V ac Wire or Terminal Connector Voltage Red/White Wire  (25) Blue Wire (26) Fuel  Solenoid Power Cable: Plugged HEATER-OFF FAN   Switch: HEATER Voltage Ventilating   Air Motor Power Cable: Plugged HEATER-OFF- FAN   Switch: HEATER Voltage White  Wire (From PC Board) (28) Red Wire 110  V  ac Combustion   Blower Power  Cable: Plugged HEATER-OFF- FAN   Switch: HEATER Voltage White  Wire (30) Yellow   Wire 110 V ac (31) Transformer Power Cable: Plugged HEATER-OFF- FAN   Switch: HEATER Voltage White  Wire (32) Yellow   Wire 110 V ac (33) Change 2        4-32.1/(4-32.2 blank) ( 5) P r o b e No.2 ( 6 ) M e t e r I n d i - cation Green   Wire (27) 28  V  dc (29)