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Keep Your Cool - RV Air Conditioners

If you have ever been camping in your RV in the summer, in Florida, WITHOUT air conditioning you know how uncomfortable that can be.

Our RV Air Conditioner is probably the most neglected system in our RV's yet it is probably the system we rely upon the most. We expect them to turn on and function well, but we tend to neglect simple preventative maintenance items that are necessary to maximize their performance, reliability, and useful life.

Air Conditioning Basics: The air conditioner is not a complex device. It essentially consists of four key components: a compressor, refrigerant, two sets of coils (condenser and evaporator) and a blower fan.

The blower motor and compressor are powered by 115 vac. The control circuitry that tells it what to do, and when to do it are powered by the house 12 volt batteries.

TIP: Both 12 volt DC and 115 VAC must be present at nominal levels for the air conditioner to work. If your air conditioner is not working - first verify that you have proper levels of 12vdc and 115vac power available.

How it works: When the thermostat initiates a cooling cycle, the fan blower starts pulling ambient air from inside the RV through filters, blowing it across the evaporator coils and back into the RV through the discharge vents which may or may not be ducted. If nothing else happened, all we would be doing is circulating the same hot air into the air conditioner and back out again.

Enter the compressor and refrigerant. The compressor condenses the refrigerant under high pressure making it very hot and sends it through the condenser coils. The fan then exhausts that heat to the outdoors through the coils returning the refrigerant back to a liquid state. The liquid refrigerant is cycled back to the evaporator coils where it expands after absorbing the heat from the air being pulled out of the RV. This now cooler RV air is blown back into the RV and the cycle repeats until the ambient RV air reaches the temperature called for by the thermostat.

It is important to note that the air conditioner does just that - it conditions the air. It removes humidity and transfers heat (BTU's) providing dryer, less hot air back into the RV. The humidity removed is the water you see dripping off the roof of the RV.

Air Flow Is King: Note that the air pulled out of the RV passes through filters. This is primarily designed to keep dust, pollen, debris, pet hair, etc. from clogging the evaporator coils. Cleaning your Air Filters is a quick, easy process that must not be neglected. It is recommended that the filters be inspected and cleaned monthly.

TIP: The RV air conditioner is NOT an air purifier. Adding additional 'super' filters to the air conditioning intake will only serve to restrict air flow and can damage the air conditioner. If you need purer air, it is recommended that you use a separate air purifying appliance to achieve that.

Enjoy fresh air in minutes with the Core 300 True HEPA Air Purifier. Featuring Vortex Air Technology and 360° air intake, the Core 300 cleans spaces up to 547 ft² in 30 minutes, 219 ft² in 12 minutes.

Speaking of clean air - note that the air we breathe in the RV has passed through the evaporator coils. When was the last time these coils were inspected and cleaned on your RV? It is recommended that the air conditioning coils (evaporator and condenser) be cleaned annually at a minimum, preferably twice a year.

Dirty Evaporator Coils

Spray Evap Foam on the coil and the foam will wash the emulsified matter off. The aerosol product is NSF registered for use as a coil cleaner in and around food processing areas, and helps leave the area deodorized with a pleasant lemon scent.

Use this product on the evaporator coils and the Frost King product shown below on the condenser coils.

Dirty Condenser Coils

Air conditioner coil foaming heavy duty detergent cleaner with low VOC formula. Not recommended for the Evaporator coils due to its strong scent. Use this one on the Condenser coils which are isolated from the air going into the RV.

The cap has coil cleaner/straightener fins which are useful on both sets of coils. I like to use a coil cleaning brush in addition to the cap to achieve a deeper cleaning,

I prefer to use only the fin brush and avoid using the metal fin comb to prevent damage to the coils.

If you prefer a root canal experience to the idea of getting on the RV roof to clean air conditioning coils, it is recommended that you hire a qualified RV Service Technician to perform this service for you. You can find a technician near you at:

Cleaning of your air conditioner coils and filters is a maintenance task that must not be neglected to keep the air conditioner reliable and performing at its best.

Short Cycling - This is an air flow condition where the A/C cycles on and off without completing a full cooling cycle which normally lasts for about 10 to 20 minutes. The compressor may run only for a few seconds or a few minutes at most. Over time, the short cycle condition can damage the compressor and you will lose your cool.

This short cycling condition can occur because of an improperly installed internal air conditioner baffle that separates the return air from the supply air.

It can also be caused by leaving the quick cool air dump vents open on a ducted system and not allowing the supply air to circulate through the ducts.

Clogged coils can also cause overheating due to insufficient air flow causing the AC to shut down and short cycle.

Fan Speed: Since air flow is paramount for proper AC operation, a low fan speed is not advisable. It may be quieter, but a low fan speed is less efficient at removing heat through the condenser coils and is prone to freezing up of the evaporator coils. It is recommended to always use a high fan speed setting.

Air Conditioner Killer: Besides a lack of sufficient air flow, the major killer of RV air conditioners is bad or wrong electric power.

See BLOG titled: Don't Fry Your RV

Connecting your RV to a miswired power pedestal can present 240 vac to your appliances designed for 120 vac. Campground 'brownouts' can present your RV appliances with a voltage level below their normal operating range which will damage them. In addition, voltage spikes from lightning strikes and other sources will also cause serious damage to RV appliances including the air conditioner.

EMS Protection: A quality EMS is a necessary RV accessory. It will kill the the power before presenting your RV with damaging low, high, and voltage spikes. It will prevent connecting to miswired RV power sources, protecting you from dangerous reverse polarity, open neutral and ground conditions.

Total electrical protection for your RV. Only device on the market to protect line and load side electrical. Most surge protection on the market!

30 AMP Model

50 AMP Model

Questionable Power: Moochdocking in a friend or relative's driveway seems innocent enough, but beware of what you are plugging your RV into. Using undersized/underrated dogbone adapters connected to underrated household power wiring/receptacles will cause your RV Air conditioner to be starved for the power it needs to start and run. It is like trying to suck a Dairy Queen Blizzard through a plastic coffee stir stick. Not only will this severely damage your AC compressor, it can cause overheating of wires and connectors posing a fire hazard.

If you plan to power your RV from a standard 120vac house receptacle:

  • Use a 10 gauge extension cord, 25 ft maximum rated for 20 amps.

  • Use adapters rated for 20 amps

  • Plug into a GFCI outlet rated for 20 amps

  • Do not use other appliances in addition to your AC. Limit your total power consumption at any one time to under 20 amps.

Your RV air conditioner compressor is the hardest working component in the appliance. It is asked to go from stationary to full speed in an instant when the thermostat says it wants the cooling cycle to start.

Capacitors are used in the air conditioner circuitry to 'kick start' the compressor motor with a high energy pulse. This spike in energy results in a momentary high amperage draw that can be 5 to 6 times the normal operating current of the air conditioner.

This jump start energy pulse is the reason why you can only run one AC on a 30amp RV and you have to be careful as to which appliances you use while the Air conditioner is operating to avoid tripping circuit breakers. This is inconvenient and problematic when RV'ing in a hot and humid environment like Florida.

The solution is to significantly reduce the energy spike needed to start the AC compressor using a soft start device. Some options are:

Soft Start Easy Start Easy Start - Bluetooth




These devices are highly effective in reducing the energy spike needed to start the AC compressor. I installed the Easy Start on my 30 amp RV and will now be able to run other appliances while the AC is running as long as the total power draw remains under 30 amps.

I chose the Easy Start since they offer a two-year warranty that covers the RV roof top air conditioner in addition to the Easy Start device as long as it is less than 6 years old.

Click the link below for detail of the Easy Start double down warranty:


I hope you have found the information in this blog useful. Remember, If you need an NRVTA Certified RV Service Technician to help you with any repairs or preventative maintenance on your RV air conditioner or other systems, you can find one near you at:

If you are selling your RV and want to facilitate a quick sale it is good to have a recent Independent NRVIA Certified Inspection report on hand to share with prospective buyers.

If you are buying a new or preowned RV, be sure to hire an independent NRVIA Certified Inspector to give you the knowledge of the true condition of the RV before you buy.

You can find an NRVIA Certified Inspector near you through the NRVIA web site locator.

Our primary objective at Sherlock RV Inspection Service, LLC is to serve you by making sure your RV is safe to occupy and all major systems and appliances are functioning as intended.

We are a mobile RV Inspection Service and will travel throughout the Southeast and beyond as needed. (subject to travel and per diem costs) Check out our web site to get to know us better and for the inspection details and sample reports for review.

Safe Travels! and Keep Your Cool!

Ron Francoeur

Sherlock RV Inspection Service, LLC

Office: 352 – 224 – 9477

Cell/Text: 678 – 360 - 6883

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