Coleman Mach RV Air Conditioner Troubleshooting: A Complete Guide For American RV Owners

Coleman Mach RV air conditioners are trusted by many RV owners for reliable cooling on the road. Yet, like any appliance, they can develop problems over time. This comprehensive guide covers the most common Coleman Mach AC issues, step-by-step troubleshooting tips, helpful repair strategies, and essential maintenance advice to keep your travels cool and comfortable. Whether your AC won’t turn on, isn’t cooling properly, or makes strange noises, you’ll find expert insights and practical solutions here.

Common Coleman Mach RV Air Conditioner Problems

Identifying the whether the issue lies with power, airflow, cooling, or control is the first step in RV AC repair. Understanding the most frequent problems can help you fix many issues in minutes and know when to call a professional.

• AC Won’t Turn On: No response when switched on.
• Poor Cooling: AC runs, but air is not cold or barely cool.
• Unusual Noises: Rattling, buzzing, squealing, or clicking.
• Water Leaks: Dripping or pooling water in or near the AC unit.
• Short Cycling: Turns on and off rapidly without cooling effectively.
• Low Airflow: Weak or no air is coming out of the vents.
• Frequent Tripping: Breaker trips when AC is running.

Initial Inspection and Safety Steps

Before starting troubleshooting, ensure personal safety and protect your equipment. Begin with these essential steps:

• Disconnect Power: Turn off the RV and AC unit, and unplug external power sources.
• Access The Roof AC Safely: Use a sturdy ladder and observe fall-safety precautions.
• Gather Tools: Screwdrivers, multimeter, flashlight, soft brush, and replacement filters.

With safety in mind, you can now proceed to diagnose and resolve AC issues.

AC Won’t Turn On: Power and Electrical Troubleshooting

When your Coleman Mach RV air conditioner won’t start, these are the most likely culprits and how to address them:

Check Power Supply And Breakers

• Power Connection: Ensure your RV is plugged into shore power and the battery is charged.
• Main Breaker: Inspect the electrical panel for tripped breakers and reset as needed.
• AC Breaker: The air conditioner often has a dedicated breaker; ensure it is not tripped.

Inspect Fuses And Wiring

• Blown Fuses: Check for blown fuses related to the AC unit in the fuse box.
• Loose Connections: Look for disconnected or damaged wiring at the thermostat and AC unit.
• Voltage Check: Use a multimeter to confirm 120V AC (or appropriate voltage) at the unit.

Test The Thermostat And Control Board

• Thermostat: Ensure it is set correctly and functioning. Replace batteries if wireless.
• Control Board: Inspect for visible damage, burnt components, or loose connectors.

If the AC still won’t start, professional diagnosis may be required for further electrical issues.

Poor Cooling: Diagnosing Cooling Performance Issues

Airflow or refrigeration problems are common causes of poor cooling in Coleman Mach AC units. Explore these steps:

Air Filter And Evaporator Coil

• Clogged Filter: Dirty filters block air and reduce cooling. Remove and clean or replace as needed.
• Dirty Coils: Dust and debris on the evaporator coil hinder heat exchange. Gently clean the coil surface.

Condenser Coil Cleaning

• Access The Coil: Remove the exterior cover and inspect for dirt, leaves, or insect nests.
• Clean Carefully: Use a brush or compressed air to clear debris from the coils.

Check For Blocked Vents And Ducts

• Registers: Ensure all interior AC vents are open and not obstructed by curtains, furniture, or dust.
• Ducting: Look for collapsed ducts or insulation in the airflow path.

Refrigerant Issues (For Professionals)

If cleaning doesn’t restore performance, there may be a refrigerant leak or compressor issue:

• Low Refrigerant: Only licensed HVAC pros should handle refrigerant recharging and leak detection.
• Compressor Failure: Listen for the compressor running. Silence may indicate a failed compressor or start capacitor.

Routine maintenance reduces most cooling issues and prolongs the lifespan of your AC.

Strange Noises: Identifying And Fixing Unusual Sounds

Unusual noises from your AC unit are often early warning signs of problems. Here’s what to check:

• Rattling Or Banging: Loose screws or fan blades striking an obstruction. Tighten fasteners and clear debris.
• Buzzing: Electrical malfunction. Listen for faulty relays, loose wires, or a bad start capacitor.
• Squealing: Belt-driven fans are rare in rooftop ACs but some noise can come from dry bearings.
• Clicking: Repeated relay or thermostat engagement may signal control issues.

If a new noise appears suddenly, shut off the AC and perform a thorough inspection before running it again.

Water Leaks And Dripping Issues

Leaking water from a Coleman Mach RV AC unit can mess up your interior and signal deeper problems. Here are the primary causes:

• Clogged Drain Pan: Dirt and algae blockages cause water to overflow inside the RV. Clean the pan and drain port.
• Poor Gasket Seal: The roof seal or mounting gasket can shrink or deteriorate, allowing leaks.
• Frozen Coils: Low airflow can freeze coils, which then melt and drip water inside.
• Improper Unit Pitch: Ensure the unit is slightly pitched outward so water runs off the roof.

Quick attention prevents water damage and mold issues inside your RV.

Short Cycling: What Causes The AC To Turn On And Off Rapidly?

Short cycling is when your AC rapidly starts and stops without fully cooling the RV. This can cause excessive wear. Possible causes include:

• Thermostat Placement: Too close to a vent or window can cause false temperature readings.
• Dirty Evaporator Coil: Restricted airflow forces a safety shutdown.
• Faulty Control Board Or Thermostat: Can misread signals and prematurely cut compressor power.
• Improper Sizing: An overpowered AC cools too fast and triggers short cycles.

Check for air restrictions and proper installation to prevent short cycling.

Low Airflow And Weak Air Output

If your RV AC is running but blowing weakly, inspect the following airflow issues:

• Air Filter: Again, a clogged filter is often the culprit. Replace monthly in heavy use periods.
• Blocked Return Or Supply: Ensure both intake and output vents are clear.
• Collapsed Ductwork: Flexible ducts under pressure may fold or develop holes, losing air pressure.
• Fan Motor Issues: The blower motor or fan capacitor may be failing and should be tested or replaced.

Restoring proper airflow ensures efficient and even cooling throughout your RV.

Frequent Breaker Tripping Or Electrical Overload

Your Coleman Mach unit may trip the breaker for several reasons:

• Dirty Coils Or Filters: Overloads the compressor, drawing excess current.
• Loose Wires: Connections in the control box or plug may arc and short circuit.
• Weak Or Undersized Breaker: Ensure the breaker matches unit specifications (typically 20 amps for most RV ACs).
• Shared Circuits: Disconnect other major appliances like microwaves and water heaters when using the AC.

Electrical issues can be dangerous—seek professional help for repeated breaker trips.

Coleman Mach RV AC Troubleshooting Quick Reference Table

Problem	Likely Cause	Troubleshooting Steps	Repair/Action
AC won’t turn on	No power, tripped breaker, thermostat or board failure	Check power, fuses, breaker, thermostat	Reset power, replace fuse, check wiring
Poor cooling	Dirty filter/coils, low refrigerant	Clean filter/coils, check for airflow/refrigerant leaks	Clean or call HVAC pro
Unusual noises	Loose parts, motor issues, relay/capacitor problems	Inspect and tighten, listen for electrical buzzing, clean debris	Tighten or replace parts
Water leaks	Clogged drain, failed gasket, ice build-up	Clean pan, check seal, inspect for ice	Clear blockages, reseal gasket
Breaker trips	Overload, dirty coils, faulty breaker	Disconnect other appliances, clean coils	Upgrade breaker, maintain unit

Thermostat And Remote Control Troubleshooting

Many Coleman Mach models use wall-mounted thermostats or wireless remotes. Control issues are often simple to fix:

• Weak Or Dead Batteries: Replace in digital/wireless models.
• Display Not Lit: Indicates power supply failure or loose wiring.
• Unit Not Responding: Reset by turning the breaker off for one minute, then try again.
• Calibration: If inaccurate, consult the manual for calibration steps or consider replacement.

Proper thermostat function is critical for reliable cooling and energy savings.

Seasonal Startup And Maintenance Checklist

Ready your Coleman Mach AC for the season and extend its lifespan with these proven maintenance steps:

1. Clean Or Replace Air Filters: At least once per season or monthly if full-time.
2. Inspect All Electrical Connections: Tighten lugs and remove debris in wiring compartments.
3. Clean Coils: Vacuum, brush, or rinse both evaporator and condenser coils.
4. Check Fan Motor And Blades: Lubricate bearings if possible and confirm blades are balanced.
5. Inspect Roof Gasket And Cover: Replace cracked, flattened, or missing seals.
6. Test For Proper Cooling: Verify expected cold air at vents and normal cycling operation.

Staying proactive with maintenance reduces costly breakdowns and heat waves on your journey.

When To Call A Professional Technician

Some RV air conditioner repairs should only be handled by licensed specialists:

• Refrigerant Leaks Or Recharging: Requires EPA-certified technician.
• Severe Electrical Faults: Signs of burning, persistent breaker tripping, or melted wires.
• Compressor Or Control Board Replacement: Advanced diagnosis and installation are required.
• Persistent Water Leaks: Roof and structural concerns may need RV shop attention.

Quickly address complex issues to avoid additional damage or safety risks in your RV.

Original Coleman Mach Replacement Parts Guide

For effective repairs, use OEM (Original Equipment Manufacturer) parts to ensure a perfect fit and reliable operation. Common replacement parts include:

• Air Filters And Registers: Fit by model number or year.
• Run Capacitors And Relays: Rated by motor start type.
• Thermostats And Control Boards: Digital and analog versions available.
• Fan Motors And Blades: Match to your AC’s serial/model number.
• Roof Gasket Kits: For sealing and weatherproofing top mounts.

Order only genuine Coleman Mach parts from reputable RV suppliers or directly from Airxcel (the manufacturer).

Frequently Asked Questions: Coleman Mach AC Troubleshooting

• Can I Add Refrigerant Myself? No, only EPA-certified HVAC professionals are legally allowed to recharge or repair refrigerant.
• How Often Should I Clean The AC? Air filters should be checked every month and coils cleaned at least twice per season.
• What Size Breaker For My Coleman Mach AC? Most models require a 20-amp dedicated breaker with 12-gauge wire.
• Is It OK To Run An RV AC On Generator Power? Yes, if the generator meets the AC’s startup and running watt requirements (typically 2800+ watts for a 13,500 BTU unit).
• My Fan Runs But No Cold Air: Likely causes are dirty coils, loss of refrigerant, or failed compressor/capacitor.

Best Practices For Preventing Coleman Mach AC Problems

Keep your RV adventures cool and comfortable by following these preventative tips:

• Operate In The Shade: Parking in shaded spots lowers AC demand considerably.
• Pre-Cool The RV: Start the AC before heat builds up inside; close curtains and shades in direct sunlight.
• Insulate Your RV: Upgrade window covers, repair weatherstripping, and minimize air leaks.
• Don’t Ignore Noises Or Small Issues: Small repairs early prevent big failures later.
• Annual Professional Service: Schedule a thorough checkup at least once a year for optimal operation.

With these practices, you can maximize performance and extend the life of your Coleman Mach RV air conditioner for many seasons to come.

Helpful Resources And Official Support Channels

If you need more help, explore these trusted support resources for Coleman Mach RV air conditioners:

• Coleman Mach Official Website – Manuals, technical bulletins, and part lookup.
• iRV2 Forums – Camper and RV owner discussion with advice from seasoned technicians and users.
• YouTube Video Tutorials – Visual walk-throughs for cleaning, repairs, and maintenance.
• RV Repair Club – Step-by-step video guides and troubleshooting checklists.

For complex or warranty-covered repairs, always contact the Airxcel/Coleman Mach support team or a certified RV technician.