RE: [A/S] Air Conditioners

["Kimm Flatt (Volt)" <a-kimmfl@xxxxxxxxxxxxx>]

He is correct.

IT is referred to as the "Alpha Beta" effect.  Back 40 years ago, the
grocery store chain Alpha Beta, got the great idea to increase the cooling
effect of their freon air conditioners by adding small water sprayers to the
condenser.  It worked wonders, but eventually eroded the metal away.  In the
mean time they had the coolest grocery stores around, and increased their
sales because of it.  To test just how well this works, try this at home:
needed; 1 ambient temperature thermometer, 1 car, 1 garden hose and water.
Park your car in the sun.  The hotter the better.  Have car running.  Turn
on A/C.  place thermometer by a/c vent.  Wait a few moments to get a good
accurate reading from the vent.  (A really good working R-12 a/c unit in a
car should be able to produce 35 to 40 degrease at the vent.  Napa ac book)
Most cars, in the good desert heat, and not moving, will not reach this
temp.  Next take the water hose and 'hose down' or spray the condenser.
(The condenser is the radiator looking thing in front of the water
radiator.)  For most cars, just spray some water thru the grill.  Watch for
the immediate temperature drop at the vent.  It will be noticeable.  Dick: I
especially want you to try this.!

R-12 freon, now a big controversy, is extremely efficient.  Think of a
vehicle, sitting in a traffic jam on the freeway, in Phoenix, AZ, in the
middle of the summer.  The shade temp can be as high as 120 degrease.  The
ambient air temperature of the air just 6 inches above the asphalt can be
150 degrease or more.  (AZ residents can confirm this.)  R-12 condense point
is somewhere in the 180's so it has no problem with the high temps.  The
volume of air in your car, the amount of air your fan can circulate, and the
size of the evaporator (the a/c radiator inside under the dash) are the
limitators.

Newer car a/c's use the "new freon"  134a.  134a is not efficient, despite
all the govt. spokes people trying to tell us that it is.  Here are some
facts to back up that statement.  The cc volume of fluid/gas, 134a, in the
units had to be about doubled.  Thus the size of the condensers and
evaporators in a/c's using 134a, had to be just about doubled.  The
condensing point of 134a is somewhere around 140 degrease.  (I can find that
out later today if anyone wants to know the exact temp)  because of that
factor alone, 134a stops working when the ambient air, reaches that
temperature.  The ambient air 6 inches off the road in the desert is above
that temp.  BUT, your car is moving so you can add in wind factor to the
cooling equation.  But if you stop at a stop light for any length of time,
the a/c vent air temperature will increase.  

Relevance:
The relevance here is that if the a/c on your Airstream is using 134a, then
the ambient air temperature, on the roof of the trailer, in the sun, at Lake
Havasau, would be so close to condense temperature of the Freon used, that
it is most possible operating at the least efficiency point.  Possible, a
few more degrease and it wouldn't be able to work at all.  I would bet tho,
that it is a R-12 unit, as it was at least achieving a 7 degree difference
inside the trailer.  Locating under a tree would help a lot.  Relocating to
a cooler part of the country, well........  I hope that the new RV a/c's are
still using R-12.  The price has gone up drastically, but that is another
story.  Made only by DuPont.  Here in the US you now have to have a license
to buy it, and only in large quantities.  Cans aren't available anymore, but
if they were they would cost about $95 a can.  They can be had for $6.00 in
Mexico.

Evaporative coolers a.k.a. swamp coolers, that's a whole different system. 

--==KIMM==--
Been known to spike cars with R-22.
(Freon used in freezers.)