Coleman RV Air Conditioner How to & Troubleshooting Guide

Besides Dometic, Coleman is the other reputable RV air conditioner brand. Coleman units include the signature series, quiet series, power saver series, roughneck series, soft start series, marine mach, and specialty units. While there is no doubt about the quality of Coleman products, sometimes these units can experience problems. Some RV owners run into difficulties operating or setting up their air conditioners.  If you are having issues with your unit, here is a troubleshooting and how-to guide for common Coleman RV air conditioners that should, hopefully, make it easier to resolve.

How to Operate a Coleman RV Air Conditioner

If your Coleman-Mach RV air conditioner is operated from the control panel located in the ceiling assembly, then there are 3 controls on the ceiling assembly that help you control the air conditioner:

  • The selector switch
  • The thermostat (temperature control)
  • Louvers

For cooling

  • Turn the selector switch to the “LOW COOL” or “HIGH COOL” position.
  • Rotate the thermostat to the position that is the most comfortable to you. The thermostat will turn the compressor on when the temperature of the air entering the air conditioner rises a few degrees above the setting you have selected. Then the temperature of the air entering continues to cycle the compressor on and off in the above-mentioned fashion until the selector switch is turned to another mode of operation.
  • Position the louvers to the desired direction the discharge air is to flo.

Short Cycling

When an air conditioner is in operation, its compressor circulates refrigerant under high pressure. Once off, it will take 2-3 minutes for this high pressure to equalize.

The A/C compressor is unable to start against high pressure. Therefore, once the A/C is turned off, it is important to leave it off for 2-3 minutes before restarting.

Short cycling the compressor (or starting it before pressures have equalized), will in some cases, kick the circuit breaker or overload.

For heating

  • Turn the selector switch to the “LOW HEAT” position. At “LOW HEAT”, the fan operates on low speed with heat output at maximum.
  • Rotate the thermostat (temperature control) switch to the position that is most comfortable to you. The thermostat will turn the heater on when the temperature of the air entering the A/C unit drops below this setting a few degrees and automatically turns off when the temperature of the air entering the A/C rises a few degrees above this setting.
  • Position the louvers to the desired direction the discharge air is to flow. Discharge air temperature can be controlled to some extent by opening or closing the louvers.

For air circulation only

  • Turn the selector switch to “LOW FAN” or for maximum air flow, to “HIGH FAN”.
  • Position the louvers to the desired direction the air discharge air is to flow.

Why is My Coleman RV Air Conditioner Not Running?

If you turning the selector switch to the “cool” position and the thermostat to a low temperature (below room temperature) and nothing happens, there could be a serious problem with the unit.

There are several possible causes for a unit failing to run:

  1. The power supply could be dead.
  2. Check for open circuit breaker or fuse at service panel.
  3. Check for 115 volts domestic USA models or 240 volts export/overseas models between hot line (black) and neutral (white) at power entrance at unit.

The evaporator coil face could be coated with lint or dirt.

Dirt or lint on the coil will restrict the flow of air through the coil and the unit must be removed from the RV and the soil must be cleaned thoroughly using a strong a detergent and water.

During cleaning, be sure to protect the fan motor and electrical controls by covering them with polythene sheet. After cleaning the system, allow it to thoroughly dry for several hours before turning on to prevent electrical shorts.

Before putting the system back into operation, be sure the filter is properly installed to prevent recurrence of dirty coil.

The ceiling assembly louvers could be completely closed.

This problem is easy to find and it is usually corrected by opening the discharge louvers.

The fan could be the issue.

A mechanical problem such as the wheel (squirrel cage) loose on the shaft is usually rather obvious.

On the other hand, checking why a fan motor does not come up to speed is a little more involved:

Seized bearings

This does not occur often, but if it does, a few drops of oil will usually free them temporarily. If the shaft is scored in the bearings, it will soon tighten up again. Now is the time to replace the motor.

Shorted or open capacitor

Perform the capacitor test using an ohm meter to determine if the capacitor is good, open, shorted or grounded. Consider these instructions below:

  • This test must be done with an analog type meter.
    • Disconnect all electrical power to the air conditioner.
    • Discharge the capacitor with a 20,000 ohm (approx, 3 watt) resistor or larger.
    • You may discharge capacitors with a standard volt meter if you use over 500 volts and touch the leads, one lead to each side of the capacitor.
    • Identify and disconnect the wiring from the capacitor.
    • Set and zero the ohm meter on the “highest” scale.

When testing a capacitor, perform the following checks:

  • Place the ohm meter leads across the capacitor terminals, one lead on each terminal, and perform a continuity test.
  • Then observe the action of the meter needle or indicator.
  • Reverse the leads and test again. The result should be the same.
  • If the capacitor is good, the indicator will move from infinity (the left side), towards zero ohms and slowly return back to infinity. Reverse the leads and test again. The result should be the same.
  • If the capacitor is open, the indicator will show no deflection or movement. Reverse the leads and test again. If there is no indicator movement on the second test, the capacitor is open. Open capacitors are defective and must be replaced.
  • If the capacitor is shorted, the indicator will move towards and sometimes hit zero ohms, and will stay there. This indicates a complete circuit through the inside of the capacitor (shorted). Shorted capacitors are defective and must be replaced.
  • When testing for a grounded capacitor, perform a continuity check between each terminal on the capacitor and the bare metal of the capacitor case. Any indication of a circuit (constant resistance) from either terminal to case indicates a grounded capacitor. Grounded capacitors are defective and must be replaced.

Partially burned motor windings

To troubleshoot this, perform the motor test. Check the resistance between each of the wires and ground (preferably a copper refrigerant tube for a good connection). These readings must be infinity. Any continuity means the windings are grounded.

If there is a reading of 0 between any two leads, the motor is shorted and is no good. If there is a reading of infinity (no meter reading at all) between any two leads, the winding is open and the motor is no good.

How Many Watts Does My Coleman RV Air Conditioner Need?

The power consumption of an air conditioner in RV will vary depending on the BTU (British Thermal Unit) rating of the AC. An AC normally will have two watt ratings: A watt required to do the start up and the watts that are consumed by it during running.

On average the numbers will be around the watts mentioned below:

  • 15,000 BTU air conditioner- Needs around 3200-3500 watts for startup, 1200-1700 watts for running
  • 13,500 BTU- Needs around 2700-2900 watts for start up, 1000-1300 watts for running
  • 10,000 BTU- Needs around 1900-2050 watts for start up, 600-750 watts for running
  • 7,000 BTU- Needs around 1600-1800 watts for start up, 500-650 watts for running
  • 5,000 BTU- Needs around 1100-1300 watts for start up, 300-450 watts for running

How Do You Reset a Coleman RV Air Conditioner?

To reset the thermostat model 9630-3361 follow these steps:

  1. put the thermostat in the off position
  2. Pull the fuse and wait 5 minutes
  3. Put the fuse back and wait another 5 minutes
  4. Then turn on
  5. Your air conditioner is now reset.

Why Does My Coleman RV Air Conditioner Keep Turning On and Off?

The air conditioner compressor cycles on and off because of two things:

  1. The thermostat is out of calibration. Turn off power. Check with ohm meter.
  2. The compressor is cycling on the thermal current overload.

With the power on, check the voltage between the terminals of the overload while the compressor is not running. If the meter reads 115 volts domestic USA models or 240 volts export/overseas models, the compressor is cycling on this switch.

When the compressor is running hot or is drawing excess current or both, this can cause the switch to open and close. To check, follow these instructions:

  • Feel the compressor dome. It will normally (during warm weather- above 85o) be too hot to be comfortable if you keep your hand on it. If it is burning hot, it is probably overheating. The normal compressor housing temperature varies with outside temperature and evaporator load so determining whether or not it is too high is a matter of judgement based on experience.
  • Measure the current (amperes) through the black wire leading from #5 on the potential relay to the overload switch. This current may be compared to the unit FLA rating.

Remember that the overload switch is sensitive to both high temperature and high current. Therefore, it is difficult to specify a definite temperature or amperage at which the switch will open. As the temperature rises, the current at which the switch will open goes down. As the temperature goes down, the current at which the switch will open goes up.

 Several things can cause the compressor to draw overcurrent or to overheat:

  • Dirty condenser coil- Check the coil’s appearance. If it is coated with lint, cottonwood fuzz, leaves, etc., it is insulated and it cannot give up its heat to the outside air. A dirty condenser will cause high head pressure which will in turn cause both high current draw and high temperature at the compressor.
  • Condenser fan does not come up to speed- Check fan blade, fan motor and capacitor.
  • High or low voltage

High voltage can drive excessive current through the motor windings. Low voltage can cause the compressor to slow down, overload, and draw excessive current. Check the voltage between “C” and “R” terminals on the compressor while it is running. The voltmeter must read between 103.5 volts and 126.5 volts (domestic USA models-plus or minus 10%).

Overcharge or non-condensables in the system

Either an overcharge of refrigerant or non-condensables in the system will cause high head pressure and consequently, excessive current. Be especially suspicious if you discover evidence of the system having been open (service valves on the system, extra pinch off marks, etc.).

Plugged up cap tube

A cap tube can become stopped up by oil sludge or contaminants in the system. This will only occur if the system has been open to allow moisture or other contaminants to enter the system or if the compressor has been overheated for a lengthy period of time.

The symptoms of a low charge and stopped up cap tube are almost similar. It is difficult to determine the difference. To repair either a low charge or stopped up cap tube, you will have to install service valves and attach a gauge manifold. If after the correct amount of refrigerant has been charged into the system, and it has low charge symptoms, you will know the cap tune is plugged and will have to be replaced.

Coleman RV Air Conditioner is Running but Blowing Hot Air

There are several possible reasons why your air conditioner is blowing hot/warm air:

  1. It may need to be recharged with a refrigerant and checked for a leak. The lack of refrigerant could be due to damage caused during shipping or it could be a pre-existing problem with the unit before you bought it.
  2. The air conditioning unit compressor could be bad. The compressor valves could be broken.
  3. It could be a bad electronic control board in the A/C unit.
  4. Bad thermostat

At this point, you must break into the system to locate the problem.

Coleman RV Air Conditioner Compressor Not Coming On

If your air conditioner compressor does not run and it does not hum, this may be due to several possible causes:

The selector switch may be open to the compressor.

To troubleshoot, rotate the switch to the compressor position and check the selector switch terminals (L to 4) with ohm meter for continuity.

Thermostat may be open.

To troubleshoot, rotate the switch and check the thermostat terminals with ohm meter. The contacts should open and close if ambient air temperatures are between 60 and 90 degrees Fahrenheit.

Overload switch may be open.

To troubleshoot, check around overload switch with ohm meter.

Compressor winding may be open

To troubleshoot, check out compressor windings with ohm meter. Be sure to remove all the leads from the compressor terminals before making this check.

  • If the resistance between any two terminals is 0 ohms, the motor windings are shorted.
  • If the resistance between any terminal and the compressor housing is anything but infinity, the winding is grounded.
  • If the resistance between any two terminals is infinity, the winding is open.

On a good compressor, the highest resistance will be between the R (run) and S (start) terminals. The lowest resistance will be between the C (common) and R (run) terminals. The intermediate resistance will be between the C (common) and S (start) terminals. You can find the identification of the terminals marked on either the terminal cover or on the compressor housing.

Why is My Coleman RV Air Conditioner Not Cooling?

If you have turned the selector switch to “Cool” and the thermostat to a low temperature (below room temperature) and the fan runs OK, but the unit does not cool, there are several possible causes for this issue:

The voltage could be low.

To check this:

  • Check the voltage between #1 on the overload switch and the “R” terminal of the compressor while it is not humming. This voltage must be 115 volts for domestic USA models or 240 volts for export/overseas models. No less that minus 10% is allowable.
  • Check the voltage from “C” or “R” of the compressor while it is humming (trying to start). The latter reading will probably be lower, but it still must be 103.5 volts minimum for domestic USA models or 216 volts minimum for export/overseas models.

If the first reading is more than 103.5 volts domestic USA and the second is under 103.5 volts domestic USA, there is too much voltage drop in the lines; a situation which must be corrected for the air conditioner to perform safely and satisfactory.

A capacitor could be shorted, weak or open.

To troubleshoot, first start by turning the power off. Exercise caution as there is always a chance that a capacitor is holding a residual charge, so before touching a terminal, discharge the capacitor.

  • Remove capacitors, visually examine them and test them.
  • If the capacitors test OK, replace them and carefully connect the wires. Make sure that the wires are connected to the right terminals.

Start relay contacts could be open (if so equipped).

To troubleshoot, turn off all power and then check for continuity with ohm meter between terminals 1 & 2.

  • Compressor start winding could be open or grounded. Check the compressor windings.
  • Compressor could be mechanically stuck.

This does not occur much often and when it does, it is usually after a lengthy shutdown. This should be considered only after positively eliminating the other possible causes discussed above.

To free a stuck compressor, use your hermetic analyzer according to the manufacturer’s instructions.

Coleman Mach RV Air Conditioner Fan Not Working

If your Coleman RV Air Conditioner fan is not working, the problem might be the fan motor. The air conditioning unit has one double-end shaft fan motor. On one shaft end is mounted a centrifugal or squirrel cage blower which draws air (return air) out of the RV and blows the conditioned air down into the vehicle. On the other end is mounted an axial flow or propeller type fan which circulates outdoor air.

To check the fan motor, follow these steps:

  1. Be sure the motor leads are connected to the proper points.
  2. The black wire from the motor connects to a black wire inside a wire nut then the black wire connects through the disconnect plug to the selector switch. The red wire from the motor connects to a red wire in a wire nut then the red wire connects through the disconnect plug to the selector switch.
  3. The white wire from the motor connects to the fan capacitor or a white wire in a wire nut then the white wire connects through the disconnect plug to the thermostat.
  4. The brown wires from the motor connect to the fan capacitor.
  • To check the motor winding resistance carefully, check the resistance between each of the wires and ground (preferably a copper refrigerant tube for a good connection). These readings must be infinity. Any continuity means the windings are grounded.

If there is a reading of 0 between any two leads, the motor is shorted and is no good. If there is a reading of infinity (no meter reading at all) between any two leads, the winding is open and the motor is no good.

Note that a motor with 2 brown leads will have an O reading between 1 brown wire and either the black or white wire.

Besides the above, other issues than could cause the fan not to work are:

The selector switch could be open

The safest way to check a selector switch is to turn off all power, remove the wires and with an ohm meter, check for continuity between terminals L&1 for low-speed fan connection and terminals L&2 for high-speed fan connection. The meter should read 0 ohms.

  • The electrical circuit to the fan motor leads could be open. Check all connections (including wire nuts) to the fan motor red, black and white wires,
  • Fan capacitor may be shorted, weak or open. To check fan capacitor, follow same procedure as outlined earlier for compressor run capacitors.

How to Change the Coleman RV Air Conditioner Filter

Filters are made from long-life non-allergenic natural fibers which can be cleaned and reused, and which completely filter the circulated air when the A/C is in operation. If the filters are not cleaned at regular intervals, they may become partially clogged with lint, dirt, or grease among other things. A clogged filter will produce a loss of air volume an may eventually cause an icing-up of the cooling (evaporator) coil.

To clean and/or change the filters:

  1. Remove the two grilles from the ceiling assembly by pulling the tabs on the grilles.
  2. Remove and clean or replace the two filters.
  3. Re-install the filters and grilles in the ceiling assembly.
  4. If the vehicle is equipped with a flush mount ceiling assembly, remove the four return air grille screws. Remove the filter from grille and either clean or replace with new filters.

How to Drain a Coleman RV Air Conditioner

It has long been known that water is the worst enemy of a refrigeration system. R-22 (and other refrigerants) will break down and change to strong acids at elevated temperatures in the presence of water. The more the water concentration, the lower the temperature at which the refrigerant will break down. The only way to remove the water from a system to a satisfactory level is to vaporize it and draw it out of the system with a vacuum pump.

To go with the good vacuum pump, a good quality vacuum gauge must be used. The pump may not pump a good vacuum due to contamination of oil. Also, a leak in the system or service hoses may prevent a deep vacuum from being reached. How long it takes for the pump to drain a system will vary with the amount of moisture and air in the system. The gauge will not show a deep vacuum (under 200 microns) until all of the water has been boiled out. Also, the system will not be properly evacuated if the system has even a very small leak. So a good gauge will indicate whether or not you have a dry system with no leaks.

Coleman RV Air Conditioner Compressor Makes Loud Noise

If your air conditioner compressor makes loud growling noise, this means power is getting to the compressor, the start circuit is starting the compressor OK and the capacitors and relay are providing the starting torque.

The noise is because the start capacitor is staying in the circuit and the compressor is running with too much capacitance. This condition is caused by any of the following:

  1. The compressor does not come up to speed and does not supply adequate voltage to actuate the potential relay.
  2. The potential relay contacts are welded shut.
  3. The potential relay coil is open.

To fix this problem:

  • Check the voltage between “C” and “R” terminals of the compressor. Low voltage can cause the compressor not to come up to speed.
  • Check out the potential relay with hermetic analyzer or try a new potential relay.
  • Check the compressor windings.

Coleman RV Air Conditioner Compressor Trips Breaker

If your air conditioner compressor trips circuit breaker or thermal overload immediately (no hum) and with the selector switch in “Fan Only” position, the fan works OK, this could be due to the following reasons:

  • The compressor winding is shorted or grounded, or,
  • The circuit breaker or thermal current overload is weak. This rarely occurs, but it can happen after the switch tripped out many times. The only repair is to replace the circuit breaker or overload.

Check this too: Why Does My RV Air Conditioner Leak When it Rains?

To repair it, follow these troubleshooting steps:

  1. With the power turned off, check the resistance between all 3 compressor terminals and ground. If there is any continuity, locate the ground and correct it.
  2. Check the compressor windings using an ohm meter. Be sure to remove all the leads from the compressor terminals before making this check.
  3. If the resistance between any two terminals is 0 ohms, the motor windings are shorted.
  4. If the resistance between any terminal and the compressor housing is anything but infinity, the winding is grounded.
  5. If the resistance between any two terminals is infinity, the winding is open.

On a good compressor, the highest resistance will be between the R (run) and S (start) terminals. The lowest resistance will be between the C (common) and R (run) terminals. The intermediate resistance will be between the C (common) and S (start) terminals. You can find the identification of the terminals marked on either the terminal cover or on the compressor housing.

  • If the above checks are OK, replace the switch that is tripping out.

Oscar

In his spare time, Oscar loves tinkering with electronics. Solar panels, wiring, old TVs and sometimes DIY powerwalls. When he is not busy trying not to electrocute himself, you can find him in the garden tending to his vegetables and chickens.

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