Troubleshoot Safety Circuits

Transcription

1 Troubleshoot Safety Circuits

2 Troubleshoot Safety Circuits GMEC96 and GMVC96 Furnaces Safety circuits serve to control any potential safety hazards, and are in place to ensure proper furnace operation. The safety circuits in this furnace serve as inputs to the ICM for continuous monitoring, and for diagnosing abnormal furnace functions. Safety circuits include: Auxiliary Limit Control- AUTO Reset Primary Limit Control- AUTO Reset Rollout Limit Control- MANUAL Reset Low Fire Pressure Switch High Fire Pressure Switch Front Cover Pressure Switch

3 Limit Switches on GMEC96 Furnace

4 Limit Switches on GMEC96 Furnace Student Exercise- Trace Limit Switch Safety Circuit Start in the blower compartment at the 12-pin connector on the ICM board. Follow the pink wire leaving pin #11, and heading to the auxiliary limits. Enter first auxiliary limit control, change color to yellow, and continue to the next auxiliary limit control. Change color to purple and proceed into the burner compartment up to the primary limit control. Exit the primary limit control as a blue wire and enter the 1 st rollout limit control. Leave the 1 st rollout limit control as a pink wire, and enter the 2 nd rollout limit control. Exit the 2 nd rollout limit control as an orange wire, and proceed back to the ICM board into pin 6.

5 GMEC96 Burner Compartment Blower Compartment 6 11

6 Pressure Switches on GMEC96 Furnace

7 Pressure Switches on GMEC96 Furnace Student Exercise- Trace Pressure Switch Safety Circuit Start in the burner compartment at the primary limit control. Follow the orange wire leaving the primary limit control, heading to the low fire pressure switch at the C connection. Exit the low fire pressure switch at the NO connection as a brown wire heading back to the ICM board. (low stage heat) Enter the ICM board- 12 pin connector, at pin #11. Go back to the low fire pressure switch and follow the orange jumper wire leaving the low fire pressure switch, heading to the high fire pressure switch. (high stage heat) Enter the high fire pressure switch at the C connection. Exit the high fire pressure switch at the NO connection as a yellow wire, and head back to the ICM board into pin #2 of the 12 pin connector.

8 Limit Switches on GMVC96 Furnace

9 Limit Switches on GMVC96 Furnace Student Exercise- Trace Limit Switch Safety Circuit Start in the blower compartment at the 15-pin connector on the ICM board. Follow the pink wire leaving pin #10, and heading to the auxiliary limits. Enter first auxiliary limit control, change color to yellow, and continue to the next auxiliary limit control. Change color to purple and proceed into the burner compartment up to the primary limit control. Exit the primary limit control as a blue wire and enter the 1 st rollout limit control. Leave the 1 st rollout limit control as a pink wire, and enter the 2 nd rollout limit control. Exit the 2 nd rollout limit control as an orange wire, and proceed back to the ICM board into pin#1 of the same 15- pin connector.

10 GMVC96 Burner Compartment Blower Compartment 10 1

11 Pressure Switches on GMVC96 Furnace

12 Pressure Switches on GMVC96 Furnace Student Exercise- Trace Pressure Switch Safety Circuit Start in the blower compartment at pin #7 on the 15-pin connector, plugged into the ICM board. Follow the orange wire leaving pin #7 heading to the low fire pressure switch at the C connection. Exit the low fire pressure switch at the NO connection as a brown wire heading back to the 15- pin connector at pin #2. (low stage heat) Go back to the low fire pressure switch and follow the orange jumper at the C connection, heading to the high fire pressure switch. (high stage heat) Enter the high fire pressure switch at the C connection. Exit the high fire pressure switch at the NO connection as a yellow wire, and head back to the ICM board into pin #12 of the 15 pin connector.

13 Troubleshooting Limit Switches- GMEC96 & GMVC96 Limit switches are normally closed and open on a rise in temperature. Limit switches can be tested individually, or the entire series safety circuit can be tested and ruled out of the problem. Testing The Entire Safety Circuit To Rule Out A Limit Issue Turn off power to the furnace. Remove the appropriate 12-pin or 15-pin connector from the ICM board.

14 Troubleshooting Limit Switches- GMEC96 & GMVC96 Testing The Entire Safety Circuit To Rule Out A Limit Issue (cont.) Review diagram and locate the wires that exit and then reenter the 12-pin (GMEC96) or 15-pin (GMVC96) connector from the ICM board. GMEC96- Pink wire exits on pin #11, and orange wire returns on pin #6. GMVC96- Pink wire exits on pin #10, and orange wire returns on pin #1.

15 Troubleshooting Limit Switches- GMEC96 & GMVC96 Testing The Entire Safety Circuit To Rule Out A Limit Issue (cont.) Test for continuity on the appropriate pins. (11 to 6, or 10 to 1) 1 GMEC GMVC If no continuity, test the suspect limit individually.

16 Troubleshooting Limit Switches- GMEC96 & GMVC96 Testing A SINGLE Limit Switch Remove low voltage wires at limit control terminals. Set meter to ohms and test between both terminals. Ohms should be continuous unless the heat exchanger temperature is above the limit control setting.

17 Troubleshooting Pressure Switches GMEC96 and GMVC96 Have Same Pressure Switches High Fire Low Fire Front Cover

18 Troubleshooting Pressure Switches To Troubleshoot a Pressure Switch Remove wire terminals, and control hose from the pressure switch to be tested. Interconnect hose with a digital manometer, using a ¼ tee. When induced draft motor starts, take ohm readings on pressure switch terminals. Switch should close and meter should show a complete across the pressure switch. If switch doesn t close, compare the negative pressure to that particular switch.

19 Manometer