May 2018 Service ManualFunction ManifoldPart No. 1275811GT GR ™ • QS™R • QS™ W 674-3Valve CoilsHow to Test a CoilA properly functioning coil provides anelectromagnetic force which operates the solenoidvalve. Critical to normal operation is continuitywithin the coil. Zero resistance or infinite resistanceindicates the coil has failed.Since coil resistance is sensitive to temperature,resistance values outside specification canproduce erratic operation. When coil resistancedecreases below specification, amperageincreases. As resistance rises above specification,voltage increases.While valves may operate when coil resistance isoutside specification, maintaining coils withinspecification will help ensure proper valve functionover a wide range of operating temperatures.Electrocution/burn hazard.Contact with electrically chargedcircuits could result in death orserious injury. Remove all rings,watches and other jewelry.Note: If the machine has been in operation, allowthe coil to cool at least 3 hours before performingthis test.1 Tag and disconnect the wiring from the coil tobe tested.2 Test the coil resistance using a multimeter setto resistance (W). Refer to the Valve CoilResistance Specification table.Result: If the resistance is not within theadjusted specification, plus or minus 10%,replace the coil.Valve Coil ResistanceSpecificationsNote: The following coil resistance specificationsare at an ambient temperature of 68°F / 20°C. Asvalve coil resistance is sensitive to changes in airtemperature, the coil resistance will typicallyincrease or decrease by 4% for each 18°F / -7.7°Cthat your air temperature increases or decreasesfrom 68°F / 20°C.Description SpecificationSolenoid valve, 3 position 4 way,20V DC with diode (schematic item E)27.2ΩSolenoid valve, 3 position 4 way,20V DC with diode (schematic item F)19ΩSolenoid valve, 2 position 4 way,20V DC with diode (schematic item H)25ΩSolenoid valve, 2 position 2 way,N.C. 20V DC with diode (schematic itemN)6.25Ω
