Coleman Mach 15 Not Cooling

Introduction

Is your Coleman Mach 15 RV air conditioner blowing warm air instead of keeping you cool? This is a common problem, especially during hot summer months, and it can quickly make your RV uncomfortable. Getting your AC working again is important for comfortable travel and protecting your RV’s interior from heat damage. Let’s walk through the steps to diagnose and hopefully fix the issue yourself!

Common Causes of coleman mach 15 not cooling

Several factors can lead to a Coleman Mach 15 not cooling effectively:

Dirty Air Filters: A clogged filter restricts airflow, making the AC work harder and cool less.
Blocked Cooling Fins: Debris like leaves, dirt, and bugs can block the fins on the condenser and evaporator coils, hindering heat exchange.
Low Refrigerant: The AC needs refrigerant to cool the air. A leak can cause the refrigerant level to drop, reducing cooling capacity.
Frozen Evaporator Coil: If airflow is restricted or the temperature is too low, the evaporator coil can freeze, blocking airflow.
Faulty Fan Motor: The fan circulates air over the coils. If it’s not working properly, cooling will be reduced.
Leaky Ductwork: Leaks in your RV’s ductwork can cause cooled air to escape before it reaches the vents.
Capacitor Issues: The start capacitor helps the motor start. A failing capacitor can prevent the motor from running efficiently.
Thermostat Problems: An incorrectly set or malfunctioning thermostat might not be calling for cooling correctly.
Voltage Issues: Low voltage from the power source can prevent the AC from running properly.

Symptoms Checklist

Use this checklist to confirm the issue:

Air blowing from the vents is warm or not cold enough.
The AC unit is running, but there’s little to no airflow.
You hear unusual noises coming from the AC unit.
Ice is forming on the AC unit or inside the RV.
The AC unit is cycling on and off frequently.
The fan is not spinning or spinning slowly.

How to Fix coleman mach 15 not cooling Step-by-Step Guide

Follow these steps to troubleshoot your Coleman Mach 15:

Check the Air Filter: Remove and inspect the air filter. If it’s dirty, wash it with mild soap and water, let it dry completely, and reinstall. Replace if necessary.
Inspect the Cooling Fins: Remove the AC shroud (the plastic cover) and carefully inspect the condenser and evaporator fins for debris. Use a fin comb or soft brush to gently clean them.
Ensure Proper Airflow: Make sure nothing is blocking the vents inside your RV. Check for obstructions in the ductwork.
Check for Ice Formation: If you see ice forming on the evaporator coil, turn off the AC and let it thaw completely. Then, try running the fan only to circulate air and prevent refreezing.
Verify Thermostat Settings: Ensure the thermostat is set to “Cool” and the temperature is lower than the current room temperature. Double-check the thermostat’s batteries if it has any.
Check the Voltage: Use a multimeter to check the voltage at the power outlet the RV is plugged into. Ensure it’s within the acceptable range (typically 110-120V in North America).
Inspect the Fan: Make sure the fan blades are clean and unobstructed. If the fan motor is humming but not spinning, it might be seized.
Listen for Unusual Noises: Grinding or rattling noises could indicate a failing motor or other mechanical issues.
Inspect Ductwork Connections: Check the connections between the AC unit and the ductwork for any loose fittings or leaks. Seal any gaps with aluminum foil tape.
Inspect the Capacitor (Advanced): This step requires caution! If you’re comfortable, carefully inspect the start capacitor for any signs of bulging or leaking. A failed capacitor can prevent the AC from starting properly. (See safety warning below!)
Run the AC on High Fan Speed: Sometimes running the AC on high fan speed can help prevent freezing and improve cooling.
Reduce Heat Load: Park in the shade, close curtains or blinds, and avoid using appliances that generate heat.
Clean the Condenser Coil: Use a garden hose with a gentle spray nozzle to rinse the condenser coil from the outside. Avoid using high pressure, which can damage the fins.

Fix the Issue Without Buying Parts

Here are some no-cost or low-cost methods to try:

Reset the AC: Turn off the AC unit and the breaker that supplies power to it. Wait 5-10 minutes, then turn the breaker back on and restart the AC.
Thorough Cleaning: Clean the air filter and cooling fins regularly to maintain optimal airflow.
Inspection Tips: Carefully inspect all connections and wiring for any loose connections or damage.
Maintenance Basics: Regularly inspect and clean your AC unit to prevent future problems.

When Replacement Might Be Necessary

If you’ve tried all the troubleshooting steps and your Coleman Mach 15 is still not cooling, it might be time to consider replacing certain parts or the entire unit. Some commonly failing parts include:

Fan Motor: $100 – $300
Start Capacitor: $20 – $50
Complete AC Unit: $800 – $1500 (plus installation)

Consult with a qualified RV technician for a professional diagnosis and repair if you’re not comfortable performing these tasks yourself.

Safety Warning

Always disconnect the power supply to the AC unit before performing any maintenance or repairs.
Be careful when working with electrical components. If you’re not comfortable, consult a qualified electrician or RV technician.
Avoid touching any moving parts while the AC unit is running.
If using water to clean the coils, be careful not to get water on any electrical components.

Tools You May Need

Screwdrivers (Phillips and flathead)
Fin Comb
Soft Brush
Multimeter (for checking voltage)
Aluminum Foil Tape
Garden Hose with Spray Nozzle

FAQ

Here are some frequently asked questions:

Q: Why is my AC freezing up? A: Restricted airflow is the most common cause. Clean the air filter and cooling fins.
Q: How often should I clean the air filter? A: At least once a month, or more often if you’re in a dusty environment.
Q: Can I add refrigerant myself? A: It’s best to have a qualified technician add refrigerant. Incorrectly adding refrigerant can damage the AC unit.
Q: What voltage should my RV outlet have? A: Typically 110-120V in North America.
Q: My AC makes a loud buzzing noise and won’t start. What could it be? A: This is often a sign of a failing start capacitor.
Q: Should I run my RV AC all the time? A: While it’s tempting, cycling the AC on and off can be more efficient. Try to balance comfort with energy conservation.

Conclusion

Troubleshooting a Coleman Mach 15 that isn’t cooling can seem daunting, but by following these steps, you can often identify and fix the problem yourself. Remember to prioritize safety and take your time. If you’re still having trouble, don’t hesitate to contact a qualified RV technician for professional assistance. Getting your AC back in working order will ensure comfortable travels for you and your family.