ICP 9MAC/E series Troubleshooting Manual

Contents

ICP 9MAC/E series Troubleshooting Manual Manual pdf 24 page image

- 24 -Status Code 8GAS HEATING LOCKOUT - This status code indicates the gas valve relay GVR on the modulating furnace control is stuckclosed or there is a miswire/short to gas valve BLUE wire. The modulating furnace control will NOT auto-reset.STEP ACTION YES NO GO TO1. Remove blower door. Disconnect communication connector PL7 (if used) or the Rthermostat lead (if used) from the furnace control board. Depress door switch.22. Does status code 8 flash? 3 63. There is a miswire or short to the gas valve BLUE wire. 44. Fix problem 55. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS. INDEX6. Does a different status code flash? 7 87. Go to page number indicated in the Index for the section covering the status code. INDEX8. Use a piece of tape to hold door switch closed. 99. Jumper R and W/W1 thermostat terminals. 1010. Does status code 8 start flashing when the low pressure switch LPS makes? 11 1211. Replace the modulating furnace control. 512. Does a different status code flash? 7 1313. Disconnect the jumper wire across R and W/W1 thermostat terminals and wait until theblower stops.1414. Cycle the furnace several times to check for intermittent operation. 1515. Does status code 8 ever flash? 11 1616. Go to page number indicated in Index for CLEANUP AND START-UP INSTRUCTIONS.If the problem persists on an intermittent basis, replace the modulating furnace control. Ifproblem still persists on an intermittent basis after replacing the modulating furnace control,contact your distributor.INDEXStatus Code 9MEDIUM PRESSURE SWITCH, HIGH PRESSURE SWITCH, OR PSR RELAY DID NOT CLOSE OR REOPENED - This statuscode can occur under the scenarios shown below. Keep in mind that whenever the modulating furnace control shuts unitdown, gas remains off or shuts off immediately, inducer continues running for 15 seconds, and if the blower is running, itremains running at minimum heat airflow or reduces to minimum heat airflow for the selected off-delay.- LOW RANGE INPUT OPERATION (40% - 51% OF MAXIMUM HEAT, 40% - 45% OF MAXIMUM HEAT ON 5T-060)1. STEADY-STATE - If the medium pressure switch input turns ON the modulating furnace control begins flashing status code 9 andcontinues to operate at the current low range input. After the call for heat is satisfied and the blower off-delay is completed the control willstop displaying status code 9.- MEDIUM RANGE INPUT OPERATION (52% - 71% OF MAXIMUM HEAT, 46% - 71% OF MAXIMUM HEAT ON 5T-060)1. PREPURGE - If the medium pressure switch MPS does not make within 45 seconds after the low pressure switch LPS made themodulating furnace control begins flashing status code 9, shuts unit down, waits 2 minutes, stops flashing status code 9, and restartsheating cycle.If medium pressure switch MPS opens before ignition, the modulating furnace control ramps inducer RPM up until the medium pressureswitch MPS remakes. When the medium pressure switch MPS remakes the modulating furnace control continues the heating cycle. Ifmedium pressure switch MPS does not remake within 45 sec after opening, the modulating furnace control starts flashing status code 9,shuts unit down, waits 2 minutes, stops flashing status code 9, and restarts heating cycle.2. LOW TO MEDIUM RANGE INPUT TRANSITION - If the medium pressure switch MPS fails to make within 45 seconds after amedium range input was requested the modulating furnace control shuts unit down and begins flashing status code 9. After the blower off-delay is completed the modulating furnace control will stop displaying status code 9 and if there is a call for heat, begin a new heatingcycle.3. STEADY-STATE - If the medium pressure switch MPS opens the modulating furnace control ramps inducer RPM up until the mediumpressure switch MPS remakes. When the medium pressure switch MPS remakes the modulating furnace control continues the heatingcycle. If medium pressure switch MPS does not remake within 45 sec after opening, the modulating furnace control starts flashing statuscode 9 and shuts the unit down. After the blower off-delay is completed the modulating furnace control will stop displaying status code 9and if there is a call for heat, begin a new heating cycle.440 08 4001 00