Class C A/C Performance

[smokeater1]

A while back I posted about our 2005 Minnie's A/C not cooling very well in 100 + degree weather.
With all the usual help in place: night shades down, roof vents covered, outside windshield cover, front privacy curtain in place, coach parked under shade tree, inside temps were only 85 degrees. It seemed most felt that was about right.
Today I contacted Winniebago tech folks. They disagreed, saying the roof mounted ducted air unit [13,500 btu] could do a lot better. Suggested I check the outlet temp. But could not give me a target temp to check for. Anyone have a idea what temp I should expect from the vents ?
Thanks,
Jack.

 

[Gary RV_Wizard]

The a/c should lower the ambient (inside the coach) about 20 degrees. If it's 90 inside, the outlet air should be about 70 or maybe 75 at the most.  it gets progressively colder as the inside air is cooled, always reducing the air moving though the unit about 15-20 degrees. The limit on the a/c's own efficiency will slow that rate down at maybe 50 degrees or so and it would likely freeze up before getting too much colder than that, so it isn't going to produce a deef freeze.

The unknown in the equation is the heat gain from outside the RV, e.g. from sun loading on the outer skin, from sun passing though the windows, from simple heat transfer from the outside air, and from air leaks.  The insulation in a Minnie just isn't all that great - certainly les than a typical stick house built in the last decade or two.    I would guess that the low 80's would be about all your rig's a/c is going to achieve in 100+ temps and direct sun. In shade it would probably get to low-mid 70's.

 

[smokeater1]

Gary, That is disappointing. I had thought it would do better. I did ask about adding a unit, the tech rep. said that was not feasible  with ducted a/c. I was thinking to add a roof unit not ducted.
In my job as a EMS pilot I see a lot of RV's camped out in the high desert of southern CA in the summer. They must have better units than mine !

Thanks,

Jack

 

[Gary RV_Wizard]

Actually, a 20 degree drop is quite good a/c performance.  It's the performance of your Rv's sidewalls, ceilings, windows, etc. that is in doubt.  Those other units probably have superior insulation and sealing - it's one of the palces where a more expensive units usually does better.

How about adding an auxiliary portable a/c unit? Take a look at units like these.I think Staples sells similar units, though probably mostly via their catalog or web site.

 

[smokeater1]

Good idea, and sure cheaper than adding a roof mount.......

Thanks,

Jack.