Basement Air in hot areas - anyone else having problems

[tnevarez]

We have a 2006 Itasca Suncruiser ad live in Mesa, AZ.  The basement air conditioner can not cool the RV when the outside temperature gets above 90 degrees.  La Mesa RV where we purchased the motorhome has checked it out and says it is cooling per specs.  They have told us that a basement air isn't very good and we will always have problems.  Has this happened to anyone else?

~Teri in AZ

 

[afchap]

My basement air works great ...even above 100 degrees keeps the inside below 80.  I would say LaMesa doesn't know what they are talking about ...basement air is every bit as good or better than roof air units that sit up there totally exposed to the heat of the sun. The most common reason a basement unit is not cooling well is air duct leaks behind the rear cap, either at the bottom "L" where the air from the unit turns upward (I have had to re-tape mine there a couple of times), OR about half way up the rear cap where the duct work comes apart. Some owners have managed to retape the joint there, others have had to have the rear cap removed. If you reach an arm up behind the rear cap on a hot day with the unit running, if you feel cool air you know there is a leak. OR, if you feel the outside of the cap and find an area that is cooler than the surrounding area, you have a leak.  It also is possible that only one compressor is running ...hopefully LaMesa is competent enough to rule that problem out...

I have tested my unit many times with an infrared thermometer.  With one compressor running the outlet temps at the ceiling ducts is apx 20 degrees lower than the air temp at the return air grid.  With both compressor running the outlet temps at the ceiling ducts is apx 40 degrees lower than the air temp at the return air grid. 

If the basement unit is working properly, it WILL do the job.  Of course, it also helps to use any awnings you have and any other shade you can take advantage of.  Some Winnie owners have added a roof ac unit, but I would want to make sure your basement unit truly is working properly before going to that extreme.

 

[SargeW]

That's sounds like they were trying to get you out of the shop.  What size is your rig?  The larger rigs, 40+ had some problems.  The other ones often had issues with the ducting getting leaks and letting the air out before it got to the inside ducts.  Check the back of the rig where the ducting is and check for leaks when the unit is running. 

Your rig won't cool to 60 degrees in that weather, but 15 to 20 degrees below the outside temps is expected. As long as you have done your part in keeping the sun out.  Closed the blinds, the front curtains if that is the direction the sun is shining. Are your windows tinted dark instead of clear? Filters clean?

Just a few ideas to start with.

Sarge

 

[catblaster]

My basement AC had several leaks on the return air side, large enough that I could poke my finger into the crack. Not only was it sucking hot outside air,it also was sucking in the air coming off of the condenser coil. Check underneath and look inside the return air duct. The foam gaskets used had deteriorated and plastic duct had warped, I'm surprised it ever worked right.

 

[mrschwarz]

My 38 foot Itasca has the same problem. You're not unique. The basement air is 24,000 BTUs. That's right on the edge of adequate. Living in Texas, we get quite a bit of 90+ weather. I cannot count the number of times it went back to the dealer to check the AC and figure out why it wasn't cooling. They reported that it was cooling within spec. The way to check if an AC is working properly is to measure the difference in temperature between the return and discharge. I think the difference is supposed to be 15 to 20 degrees. If it is that much, it is working properly. In that case, the real problem is lack of cooling capacity. This can be caused by poor insulation, air leakage, or an AC unit that is too small.

Reduce the heat load as much as you can. Cover the windows, put up awnings, check for air infiltration or missing insulation. I solved the problem by removing the roof vent in the kitchen and replacing it with a 15,000 BTU roof air unit.

 

[mrschwarz]

I forgot to mention that my 34' Suncruiser had the same AC unit and it kept the coach cool even in the heat of the Texas summer.

 

[afchap]

The way to check if an AC is working properly is to measure the difference in temperature between the return and discharge. I think the difference is supposed to be 15 to 20 degrees. If it is that much, it is working properly.

I've seen that "15-20" difference cited over and over, and still don't believe it ...naybe for a single compressor unti, but we're talking about a dual-stage compressor here. As stated above, a 15-20 degree differential is what my unit -- a 40' rig with dark paint -- does with just one compressor stage running. Surely I am not that uniqie ...

 

[John Canfield]

Paul - you're lucky with that kind of performance!  With dark paint, multiple slide outs, full sun and 40' of linear space to cool 24,000 BTU barely (or doesn't) keeps up with the heat gain in 90 degree temps.

Basement air was probably very adequate with units of <40', no slide outs or one slide out and white bodies with a few decals.  With dark paint and lots of interior area, it just isn't enough BTUs of cooling power.  With 60,000+ miles of experience with our Horizon (and two different basement units), and hot weather experience from humid Florida to 112 degree temps in Gila Bend, AZ I have ample experience to report.

The perfect solution for us was to add 13,500 BTUs of roof air - that has made a humongous difference in our comfort and now we can quickly cool down a hot coach after a hot day on the road, or keep it cool in hot weather.

 

[taoshum]

I guess it doesn't get very warm in Winnie Wonderland.  Leaky ducks and under-designed a/c but somehow they are the ones who are still doing "well" in the RV/MH bidness...  At least they answer the phone.... LOL.

 

[Gary RV_Wizard]

Air conditioning in RVs is mostly pretty dismal. Under capacity, noisy & leaky ducting, poorly laid out vents and returns, etc etc. It's an area where few, if any, RV manufacturers do well. (Newmar is one of the better ones).

And the RV itself is generally bad on heat gain, but that's sort of the nature of the beast. Low ceilings, lots of windows, and almost all the walls are exterior walls and thus sources of heat gain (and loss too).

 

[John Canfield]

.. and almost all the walls are exterior walls and thus sources of heat gain (and loss too).

So true.  I've previously used a non-contact IR thermometer on our inside walls that were in full sun and I think I was reading about 90 degrees or high 80s - I forgot what the outside temps were.  Just yesterday afternoon I was feeling the aluminum frame on a window by my recliner and it was so hot I had to remove my hand after about five seconds. 

If you can't add more insulation (or like to park in full sun like we do for the dishes), the solution is to throw money at the problem by adding more cooling capacity.

 

[Art In Mobile]

Back in my large boating days I saw a 45 foot yacht in all black fiberglass! Here in Mobile Alabama there are not enough marine air conditioners to begin to cool it down. I think it was made to only travel in Alaska.
I for one do not understand why any RV manufacturer would use a dark color on their coaches. Tiffin motors right here in Red Bay Alabama has learned the hard way that the sun can get the fiberglass so hot it is causing cracks to develop in the fiberglass. They STILL seem to be using dark colors. They are down south so they should know better. The sign of a true southerner is that he or she owns a WHITE car. Just putting your hand on the top of a car with a black roof will teach us all a lot. Earlier boat seats used to be black till people sitting on them in bathing suits would be burned on their skin.
Some of the blame has to go to us. If we buy black boats they will make them.  We should realize that insulation in RV sides is not to efficient. So why don't we start spreading the word that WE want colors that will help with the A/C. They make what sells.  As a forum we should help educate the prospective RV buyer as to why a dark color is not good. Just my two cents. Art In hot Mobile Al. 

 

[travelingsages]

You might call Gene's RV & AC Repair in Mesa. 480-833-7210 They know how to work on the basement air conditioners and are highly rated. I have used them and recommend them.

The other issue to consider is the orientation or your motorhome to the sun. Don't park with one side facing south where it will get sun all day. Try to have the rear face south. Have your windshield face north away from the sun. Cover your windows with sunscreens on the outside. Put window awnings on. Use your patio awning and even consider an awning drop to keep the sun  off the side. Solar gain is a killer. I know you can't find many trees in Mesa but park in the shade wherever possible.

 

[FrontrangeRVer]

My 36' Voyage has always had the same problems, and our units have only 24K of cooling capacity....not nearly enough for these larger units.  There are some that have installed an extra roof air in the middle of the motorhome where the spare vent is, just to make up for the lack of Winnebago engineering on cooling loads.

PS....our unit will cool to about 80 in outside temps of 95 plus.....its totally unacceptable in my opinion, and LaMesa is RIGHT ON with their response.   

 

[navy flier]

Well, just to throw another oar in the water we have a 40-ft Horizon now and had a 36-ft Horizon previously. In both of those coaches the basement air works(ed) great. And, in both of the coaches we have spent plenty of time in northern Nevada in the summer time. We have experienced temps of 105 deg with interior temps in the high 70s, more than comfortable in the dry climate. With the 40 footer you probably realize that we have the worst situation; largest coach with the largest basement air available. In addition, in Missouri in July and August (love that humidity) we are also very satisfied. 

 

[azloafer]

We have a 2006 Itasca Suncruiser ad live in Mesa, AZ.  The basement air conditioner can not cool the RV when the outside temperature gets above 90 degrees.  La Mesa RV where we purchased the motorhome has checked it out and says it is cooling per specs.  They have told us that a basement air isn't very good and we will always have problems.  Has this happened to anyone else?

~Teri in AZ

We had the same problem and had a 13,500 roof top unit added in place of the kitchen exhaust fan.  Our install was quite similar to what the moderator John Canfield did.  Now we can be comfortable in any kind of weather, no matter how hot it is.

2008 Itasca Latitude diesel 39W

 

[catblaster]

Since I made repairs to my basement air and fixed the holes winnebago left in the floor I am staying cool. It was 96 degrees and heat index of 111 yesterday. There is one oak tree on the side for a little shade in the evening. We am replacing the flooring so as expected the door is open and shut quite a bit, even so the temp inside is maintaining 75 degrees. The redundancy of adding a rooftop unit would be reassuring in case the basement air goes out completely. More air is better!

 

[GG1]

2 wks ago in Pa we had a week of 100 degree temps peaking off at 104 in the sun. We were on 30 amps inside temp was 78 during the hottest period. Had to put fridge on lp and h water heater also.  Guess that was pretty good considering the temps. It helps if you start out early in the am with the ac and keep the sun out until it goes down. Block the sun out completely from the windshield if your facing it. We use the outside sunscreen inside drape and the large aluminum foil accordian sun blocker.

 

[Old Snipe]

A couple of things to help the basement air:

Ensure that any a/c duct vent near the thermostat is either closed or turned to blow cool air away from the t-stat.

Turn the t-stat temp down to say 65 degrees so the a/c will run longer or non-stop.  Set the fan to "ON" instead of "AUTO" to keep the cooled air circulating.

Make sure your filter screen is changed out regularly.  I have heard that the extended 3 month filters instead of the the blue monthly change filters restrict air flow.  I have to test that out, I use the extended filters and they really seem to clog up quickly.

Test the incoming voltage from the power post, voltage on the lower side will keep the a/c compressors from operating at peak designed specs.  Many campgrounds have old, inadequate wiring and have significant voltage drops on hot days when everyone in the cg is running their a/c.

I close the ceiling ducts in the bedroom during the day so more air will flow to the living room.  At night I reverse the ducts, closing the living area ones and opening the bedroom ones.

In hot weather, I leave the a/c running all the time.  It keeps all the stuff inside cool.  Shutting off the a/c while going out during the day will take lots of cooling to chill things back down to a comfortable level.  Everything will absorb heat, which will tax the a/c's cooling ability.

If it is really hot, consider pulling in your slides to reduce the area that needs to be cooled.

Best Regards!

 

[mrschwarz]

I addition to the post above, keep your shades closed and get your coach out of the sun.