Saturday, December 2, 2023


It’s 89 out and my RV’s air conditioner only “cools” it to 86. Help!

Dear Dave,
My air conditioner is working and blowing cold air but can’t keep up with outside temperatures. Both compressors seem to be working. I just had the Freon checked and that’s good. We are camping now, and the outside temperature got to 89 and the thermostat in the camper said 86. The unit didn’t turn off all day until about 10:00 at night, when the outside temperature dropped. I’ve also changed filters and cleaned the condenser. Any suggestions? —Tim, 2006 Winnebago Adventurer 37

Dear Tim,
Your Adventurer has a basement-mounted central air conditioning system, called True Air, which Coleman designed for Winnebago. It is basically two compressors packaged into a residential-style unit, typically on the passenger side at the back.

The unit actually ran 25 percent more efficiently than traditional roof air conditioners. However, it was not received well in the market as it took up valuable storage space, especially when designed in a diesel pusher. The engine took up the entire back end and the True Air took up a large compartment in the middle of the rig. The plenum had to be placed inside the living area. It also was noisy in the bedroom if it ran at night.

My first question is, how did you check the Freon? All RV air conditioners have a closed system with copper piping that is pinched off and soldered with silver. There are no ports like in automotive or residential models, so it can not be “charged” or checked with gauges.

Check the air conditioner filter

The filter for this is typically under the bed pedestal. The first thing I would recommend is to make sure you have the correct filter. Using a residential-style filter could cause air restriction and affect performance. Here is the location of the filter and sizes. Note that the filter cannot be thicker than one inch and is made of lightweight fiberglass. Do not use the “lifetime”-type filters that can be washed as they will restrict airflow. Also, make sure there is nothing blocking the filter and the air return vent in the base of the bed pedestal. Make sure the door is open to draw air from the front of the rig. I have found that adding a floor fan in the bathroom helps move air more efficiently.

You also stated that you cleaned the condenser, which is accessible from the outside of the rig by lifting up the panel. This is a good first step; however, the evaporator coil is just as important and is harder to get at. Here is an exploded view of the unit. You will see the evaporator coil is #13. You should be able to access it through the opening of the filter area and vacuum it.

The next step would be to get an airflow and temperature gauge called an anemometer, which you can get on Amazon here.

This will give you the exact temperature of the air going into the return air and air coming out of the vents. The system should be able to reduce temperature by 16 degrees. If it is not, then it is not working as designed. If it is, you might have poor airflow, which the meter will also determine. Then it would be time to have a technician check the amp draw and motor.

One last thing that I got from my Airxcel contact is check the air delivery system which is called a plenum that comes out of the unit underneath and goes up through the back wall of your unit. This plenum has several connections that could have separated the cool air is leaking out into the back cap? Get a flashlight and look up behind the fiberglass back cap and you should see the plenum coming out of the unit and going up between the cap and the back wall. If there are any gaps the cool air will escape and not get to the inside.

 You might also enjoy this from Dave 

House air conditioner blows air but it’s not cold. Why?

Dear Dave, 
The house air conditioner is not working. The unit comes on and the air blows through the ducts but it’s not cold. It is a Coleman-Mach 15,000 BTU. Thanks. —Glenn, 2018 Winnebago Sunstar LX

Read Dave’s answer.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.



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DW/ND (@guest_241914)
5 months ago

Like Spike below, I could not be happier with an AC design like the basement model. It takes a cargo bay up front, under the couch on ours – but it is efficient, fast and quiet! What more could you want? Just two days ago it was 98 deg F with about 50-60% humidity and 104.5 deg F in the motor home (Winnebago Vectra 34′), which was closed up all day. Cooled to 85 in about 25-30 minutes, when I turned it off. This on only 1 compressor and 30 amps.

Oh, it has also worked flawlessly – since 1994! Keep it clean, change filters and cover it in the winter in snow country.]

roy saxton (@guest_241812)
5 months ago

friend of mine had a similar model. in the back right corner of the coach, when the ac was running, cold air was coming out from the bottom right corneer of the end cap. the plenum had become unsealed. had his very skinny girl friend was able to stand up inside the rear cap and reseal it.

Spike (@guest_241802)
5 months ago

Surprised to hear consumers didn’t like this AC. I had two Journey DPs and LOVED the basement air. Low noise compared to rooftop AC roaring over my head, no big holes in the roof to develop leaks around AC gaskets, one household style filter, no condensation draining off the roof, and as mentioned, WAY more efficient in energy usage.

I would gladly give up a basement bay to have that system and all of its benefits again.

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