NBK Parts 20455 -- Coleman Mach RV Air Conditioner Blower Motor
A true drop-in replacement for the original Coleman Mach blower motor. If your RV air conditioner is blowing weak, noisy, or not at all, this 1/4 HP, 2-speed Century motor restores full airflow without cutting wires or fabricating mounts. It replaces Coleman part 6757B311 and fits the same bolt pattern and shaft dimensions as the factory unit.
The blower motor is the heart of your Coleman Mach air conditioner -- it moves conditioned air through the shroud and into your RV living space. When the motor fails, you lose cooling entirely regardless of whether the compressor is still working. The NBK Parts 20455 gives you a manufacturer-spec replacement built to the same dimensions and electrical ratings as the original, so the swap is mechanical and straightforward.
This motor ships pre-configured with the correct shaft length, rotation direction, and speed tap wiring for Coleman Mach units that originally used the 6757B311 motor. No adapters, no shaft cutting, no rewiring required for a direct swap.
5-3/4" shaft on both ends -- 1/2" diameter -- matches Coleman OEM blade hub dimensions exactly.
High and low speed taps match the original wiring harness. No splicing or aftermarket speed controllers needed.
Built-in thermal overload protector shuts the motor down if it overheats, protecting both the motor and your AC unit.
Clockwise rotation viewed from the lead end -- correct orientation for Coleman Mach blower wheel airflow direction.
The NBK Parts 20455 is a direct replacement for Coleman OEM part number 6757B311. It is designed for Coleman Mach rooftop RV air conditioners that used this motor in the blower/evaporator section. If your existing motor has the same shaft dimensions (5-3/4" x 1/2" x 5-3/4") and a 2-speed configuration on 115V AC power, this is your replacement.
Shaft dimensions, mounting bolt pattern, rotation direction, and speed tap wiring all match the original Coleman 6757B311 motor. Remove the old motor, transfer the blower wheels to the new shafts, reconnect the wiring harness, and reinstall.
This motor uses sleeve bearings, which is consistent with the original Coleman Mach design. Sleeve bearings run quietly and are well-suited to the intermittent duty cycles of RV air conditioning. They require the motor to be mounted within the orientation range specified -- typically horizontal to slightly inclined. Mounting the motor vertically shaft-up or shaft-down for extended periods is not recommended and may shorten bearing life.
Coleman Mach produced many air conditioner variants over the years. Not every Coleman Mach unit uses the 6757B311 motor or the 5-3/4" x 1/2" x 5-3/4" double shaft. Cross-reference your existing motor's nameplate -- specifically HP, voltage, RPM, shaft length, shaft diameter, and rotation -- before purchasing. Installing a motor with incorrect shaft length will prevent proper blower wheel seating.