IV–12A08 Engine Stallc Error detection methodDuring engine operation (complete combustion), when engine revolution speed ≤ 100min -1 continuously for 3seconds, the engine is stopped momentarily and an error flag is set.An Engine Stall condition is assumed when the error flag has stopped the engine 5 consecutive times in 1 hour.d Troubleshooting1Fuel 1-1 Has the fuel gas pressure dropped? Is the fuel empty? OK 2-1NG Restore2Engine 2-1 Measure compression (See A06 5-1). OK 2-3NG 2-22-2Check 2-1 again after washing the valve and adjusting the valveclearance.Any problem with compression?OK 2-3NG Replace enginehead2-3 Is the air cleaner soiled? (Visual inspection)OK 2-4NG Clean andReplace2-4 Are spark emissions normal? Yes 2-7No 2-52-5 Inspect ignition plug (see A06 2-3) OK 2-6NG Replace2-6 Replace the ignition coil, cam angle sensor and crank angle sensor one by one to identify thedefective part.2-7 Inspect the zero governor (see A06 3-1). OK 2-8NG Restore2-8 Is the ignition timing okay? (see Chapter 5 (9)). OK 2-9NG Adjust2-9 Is air being sucked in? Check the rubber plug on the intake manifold. OK 2-10NG Replace2-10Is 4V DC (approximately) being applied between outdoor unit’s mainboard connector 6P (black) CN066 No. 1 (+) and No. 2 (-)/No. 3(-) and between No. 4 (+) and No. 5 (-)/No. 6 (-) when the power isturned on (during positioning)?Yes 2-11NoReplace theoutdoor unit’smain board2-11Is DC voltage being applied between outdoor unit’s main boardconnector 6P (red) CN065 No. 1 (+) and No. 2 (-)/No. 3 (-) andbetween No. 4 (+) and No. 5 (-)/No. 6 (-) when the power is turned on(during positioning)?Yes 2-12NoReplace theoutdoor unit’smain board2-12 Inspect the mixer’s stepping motor (both the throttle and the fuel gasadjustment valve.) Are any wires severed?Yes Replace thestepping motorNo 2-132-13Are the throttle valve or fuel gas adjustment valves locked in place?Is it possible to easily move each valve by hand with the steppingmotor removed?Yes 3-1No Replace mixer3Engine loadcheck3-1There is a chance that the engine load could be unsuitable. Check the following, and makerepairs if problems are found.• Is the air filter on the indoor unit blocked? (Especially in the heater mode.)• Has a short circuit occurred with the air on the indoor unit? (Especially in the heater modewith the remote controller’s thermostat.)• Has a short circuit occurred with the air on the outdoor unit, or is the air heat exchanger onthe outdoor unit closed, etc.? (When in the cooler mode.)• Is the refrigerant route blocked (strainer, dry core, etc.), is the valve closed (forgotten to openclosed valves, etc.,) or is the motor-operated valve locked in place?• Has the refrigerant been over-filled?● For work procedure for replacing outdoor main board, see “5. Reference Document”.● For board and Electrical Wiring Diagram, see Chapter 6.• Outdoor main board: page VI-2• Outdoor power board: page VI-3• Converter board: VI-4• Indoor control board for DC motor models: page VI-5• Outdoor Unit Electrical Wiring Diagram: page VI-6
