Coach is 2009 Marquis with rear bath layout.  Still learning our one year old coach with 12,000 miles.

Driving in hot weather we have uncomfortable inside temperatures.  Yesterday was 95 degrees outside as a high and the living room was 79, bedroom was 85, and rear bath was 90 while driving with Tstats set at 62, high fan and dash AC on. I have checked the in/out temp difference of the AC's and we are getting at least a 20 deg. difference.  The AC's cannot keep up while driving on hot days.  I realize the engine/tranny/road heat/etc. are big heat producers, but I don't feel we should be this hot.

Once we are parked and engine cools, the AC's keep us cooler, but even on the hottest days we seem to run out of capacity and the AC's cannot keep up (Full awnings, blinds and shades out).  

Some remedies I have tried:
1. Had AC's serviced
2. Checked flow - seem sdequate but I would not call it strong.
3. Running fans to circulate
4. Watched generator voltage/amps yesterday Leg 1-120V/17amps   Leg 2-116V/44 amps

Could I be missing insulation?  Rear insulation not sufficient or maybe whole coach insulation is inadequate?
Is the coach creating some type of vacuum and is drawing cool air out while we drive?
Washer/dryer vent sucking all our air out?
Could the generator not keep up with demand?

Thanks in advance for any advice?

Bob

Bob, I see you are getting no answers for the cooling problem so decided I would post a reply just to renew your hopes. I don't have an answer as my coach is an 03 Monterey but it sounds as though you have given it a good test. One thing, have you tested the a/c units 1 at a time to verify they are working properly? Hope someone with a similar coach can give you more info. Where are you located with these high temps?

We have an 03 Marquis with two AC's and I would have to say that it takes a long time for the coach to cool. If the outside temp is over 100, it never get much below 80 until after dark.  The bathroom has no AC outlet so it never cools well unless you leave the door open.  We usually run both AC units while driving in hot weather and don,t shut it down until you are in the camp spot and hooked up..  The trick is to not let the coach get hot, it takes two long to get it cool again.

The truth is the the insulation in RV is not as good as in the average home.  The more slides you have the worse it is as they have thinner walls to save weight and increase the area to cool.  in hot weather it is difficult to get 20 to 25 degrees  below  temp.  We have even left the slides closed to reduced the area cooled.

Bob

  We have an 06 Monterey and found that there was no insulation in the front cap.  We were able to pull out the tv and the dvd player and install insulation between the aluminium frame and the front cap.  We used regular insulation for from Lowes that had a plastic moisture barrier on both sides. It was 15  1/2 inches wide and was a perfect fit. I also purchased some spray adhesive to hold it to the cap but it was not needed since the supports were just close enough to the cap to hold it in place. Made a big change in temperature in the front area.
  We also pulled the dash cover and installed insulation behind the wood across the front of the lower section and wrapped the air conditioner hoses with insulation to prevent condensation and made the air discharge cooler from the the dash air.

Roger

Bob,
We have the same coach and I have to say we have not experienced the same problem. In fact we seldom run the roof air unless temps are above 90. Even then if we run two of the three we can stay quite comfortable. If temps are >100 we have to run all three to stay cool. It sounds like you do not have wall insulation or proper roof insulation. Our coach was delivered in November of '08 and was probably one of the last few coaches made by Beaver as a spec coach. We have discovered several "spare" parts that have been installed or "not exactly standard" parts. It seems they used a few left-overs to assemble our coach. Wiring also gives us some problems but our air works great. The coach seems to be well insulated. I would definitely check the lining of the engine bay since that seems to be the hottest area in our coach. Will sometimes take a couple of hours to cool down the bed/bath after we stop for the evening. But we like it cold so temp is usually at around 68.  

An infrared thermometer could be useful to detect the hot spots on your coach so that you could possibly add insulation.  A company called FLIR makes thermographic cameras that can very accurately document the hot spots in your coach. The equipment is very expensive but there are companies that offer thermographic studies of homes for HVAC needs.

One other thing... be sure to check your intake filters under the ceiling trim in the LR and BR and change them frequently. I buy bulk carbon impregnated filter material and cut to fit the intake. I change them about every 3-6 months but we do not full time. If I full timed I would change them every other month.  
Hope this gives you some ideas.
Steven Link