Coleman Mach 10 AC Motor Replacement - Shaft Too Long Fix

The Quick Answer

The tight, long shaft you're encountering suggests you may have received the wrong motor part number for your specific Coleman Mach 10 application. Different RV installations require different shaft lengths, and motors should be ordered with the correct shaft length rather than modified. Unlike the videos you've watched of other Coleman Mach units, the Mach 10 specifically used in Winnebago applications sometimes has this extended shaft configuration to accommodate the specific mounting depth in your Era's ceiling assembly.

What's Causing This

Different Coleman Mach 10 configurations require specific motor part numbers with appropriate shaft lengths for various RV ceiling thicknesses and mounting configurations. Your Winnebago Era likely has a shallower ceiling cavity or different mounting bracket setup compared to other RVs, which is why the replacement motor shaft appears too long. The extreme tightness you're experiencing is due to the shaft bottoming out in the fan hub or hitting the interior ceiling assembly before the motor can seat properly.

This is a common issue with Winnebago Era models from 2009-2015 that used the Coleman Mach 10. The original equipment motors were often pre-cut to the correct length during manufacturing, but replacement motors come with the full-length shaft that needs field modification. The shaft material is typically carbon steel.

Tools You'll Need

For this specific Coleman Mach 10 motor replacement on your Winnebago Era, you'll need specialized tools beyond basic RV repair equipment. Start with a high-quality metal cutting disc or angle grinder with a fine-tooth metal cutting wheel. You'll also need a steel ruler or caliper to measure the exact shaft length needed, as specified in the manufacturer documentation for your specific model.

Additionally, gather a metal file or grinding stone for smoothing the cut shaft end, penetrating oil like PB Blaster or Liquid Wrench for the tight connections, and a shaft puller tool if the fan hub is seized onto the old motor shaft. Don't forget safety equipment including safety glasses, gloves, and a dust mask when cutting the metal shaft. A torque wrench will be essential for properly tightening the motor mounting bolts to manufacturer specifications.

Step-by-Step Fix

WARNING: Before beginning any work, disconnect all electrical power to the air conditioning unit at the breaker panel and verify power is off with a multimeter.

First, carefully measure your original motor shaft length from the motor housing to the tip - this is your target length for the new shaft. Remove the new motor from its packaging and compare shaft lengths. Mark the new shaft at the correct cutting point, typically 1/4 to 1/2 inch shorter than it currently is. Use your angle grinder with a metal cutting disc to carefully cut the shaft, making sure to cut straight and smooth.

After cutting, file or grind the shaft end smooth to prevent damage to the fan hub. Apply penetrating oil to the fan hub if it's still stuck on the old motor shaft, and use a proper puller tool to remove it without damage. Clean all debris from the motor housing area and check that the new motor's mounting holes align with your existing bracket system.

Install the fan hub onto the properly-sized replacement motor shaft, ensuring it's seated at the same depth as on the original motor. Ensure the hub is properly seated on the shaft according to manufacturer specifications. Mount the new motor into the housing, connecting the electrical leads according to Coleman's wiring diagram for your specific model (wire colors may vary by model year - verify with dealer documentation). Test the motor operation on both high and low speeds before reassembling the complete unit.

Finally, reinstall the air conditioner into your Winnebago Era's ceiling, ensuring all gaskets and seals are properly positioned. Test all functions including cooling, fan speeds, and thermostat operation. The motor should run quietly without vibration - if you notice excessive noise or vibration, double-check that the fan hub is properly balanced and seated on the shaft.

When to Call a Pro

If the motor shaft length doesn't match your installation, verify the correct part number with a Coleman dealer or RV service center rather than modifying the shaft. The shaft cutting requires precision - too short and you'll need another motor, too long and you'll continue having the same problem. Many RV repair shops can cut the shaft to the exact length needed for your Winnebago Era's Coleman Mach 10 for around $50-75 in labor.

Also consider professional help if you encounter electrical issues beyond the basic motor replacement. Coleman Mach 10 units can have complex wiring with multiple capacitors and control boards, especially in Winnebago applications that may include integrated thermostats or zone controls. If your unit isn't cooling properly after motor replacement, or if you're seeing unusual electrical readings, a certified RV technician can diagnose issues with the compressor, refrigerant levels, or control systems that are beyond typical DIY motor replacement scope.

Tools & Supplies You'll Need

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