Troubleshooting guide

Coleman-Mach rooftop AC low voltage or extension-cord startup

Coleman-Mach FAQ and installation guidance warn that long or light extension cords, 15-amp outlets, cheater adapters, too many 30-amp loads, and voltage drop can leave the rooftop AC or heat pump unable to start or stage normally.

Use this atlas to identify likely meaning and prepare for service. Shut off power, LP gas, fuel, or water when a listed appliance condition involves flame, gas smell, exhaust, generator shutdown, high temperature, moving jacks/slides, refrigerant, 120 VAC, control boards, repeated ignition failure, or a persistent lockout. Call the appliance maker, RV dealer, or a qualified RV technician for repair.

Owner-safe checklist

Stop the cooling call from normal controls if lights dim, the compressor will not start, or voltage warnings appear.
Use the RV's normal shore-power or generator setup instead of long light-gauge extension cords or 15-amp cheater adapters.
Turn off other heavy loads on a 30-amp hookup before retrying cooling.
Call qualified RV electrical/HVAC service if the compressor still will not start or voltage drop is suspected.

Official sources