AC not cooling in 115 degree heat

It is amazing how much difference parking under a tree makes. Heating up the roof adds 10-20 degrees.

wbwood wrote:
Open up the awning and pull out a lawn chair and enjoy the desert breeze with a cold beverage of choice.

A great way to enjoy the dry desert heat. ;)

(However there's no un-air-conditioned way, short of swimming, to enjoy/tolerate the humid Eastern/Southern U.S. heat!)

We have an external entertainment center in our RV with a 12 volt receptacle in it. In the dry desert heat - if the winds aren't blowing much - I've sometimes been known to sit outside under the awning with a cold drink and have one of these plugged into this outside 12V outlet and sitting on a table blowing directly at me. By the way, these use so little power (even though moving A LOT OF AIR) that even a modest solar panel can power one directly:

http://www.fantasticvent.com/products/endless_breeze/endless_breeze.html

Here's an interesting and very practical way to use them inside your RV for low power consumption comfort in hot weather:

http://www.andybaird.com/travels/gertie/fans.htm

Open up the awning and pull out a lawn chair and enjoy the desert breeze with a cold beverage of choice.

Great suggestion pnichols. In Florida this time of year the inside of our Class C, the same model as Holiday27's get to 90 inside when sitting for awhile. It assumes the ambient temp. It takes about an hour to get her back down to 80 also. The A/C was gone over recently, cleaned etc.
When we first get ready to go I start the coach A/C and them use the A/C from the engine also. It speeds up the process of getting to cool down. I also have the reflective windshield covers and side window covers for the cab.

In hot weather, we sometimes prop open the hood of our Class C after a long drive so as to create a natural convection air flow from underneath the front of the chassis out of the open hood to cool down the engine compartment.

This takes a tremendous cooling load off the RV's air conditioning system during the first few hours of cool-down when camping.

We were just camping in 102 deg. Temp. After I got everything set up I looked at the temp inside. It was 90! I kicked the ac on and it took an hour to drop to 80. I was surprised it took that long. I think one of the factors was that everything was so hot on the vehicle from driving. The clean job seems like a good idea and I'm going to check mine out closely.

Depends on what you mean by "the inside won't get cold." Are you trying to get it somewhat cooler than the outside, or are you trying to get it down to what your would consider cool in the PNW? The latter isn't going to happen.

I've found very few type C RVs that have enough insulation and cooling capacity to get down below 80-85 F in full sunlight, even if the air outside is only 105 F. At 115 F, the A/C is even less capable of throwing off heat to the outside, trying to cool the condenser with air that hot.

If you are in full southwestern sunlight, don't expect much more than 20 F below the outside air temperature. But things should work a lot better in the shade, and at night, you might get the inside as much as 30 F cooler than the outside air temperature, assuming that has dropped for the night also.

FWIW, when I've lived in hot summer climates, I like to set the A/C no more than 15-20 below the daily high. Otherwise, going inside to outside is too hot, outside to inside is too cold. You acclimatize, often in a very short time.

Right now, sitting on the porch, sun down, temperature down to 83, a little wind feels like a cool breeze, after working in the sun all day with temperatures in the high 90's. Inside thermostat is set to 80, and air coming out of the vent gets so frigid I'll sometimes use a lap robe, because I'm dressed for summer, not winter.

Even if your air conditioner is working perfect, the heat (BTU) gain rate of your RV must be less than the heat (BTU) removal rate capability of your air conditioner in order for your air conditioner to cool the interior to any temperature you want, after enough time, regardless of the ambient exterior temperature.

It's true that most air conditioners can reduce their exit air temperature (going into the RV's interior from the A/C) only about 20-25 degrees below the entrance air temperature (coming into the A/C from the RV's interior). This interior air recirculating cycle means that if the air conditioner is large enough to always "swamp out" all heat gain of the RV's living area from any conceivable outside ambient temperatures, then the interior should be able to be kept at, say for example, 72 degrees even in outside extremes as summer Death Valley ambient temperatures.

We intentionally bought a small Class C RV to, among other things, keep it's interior living area as small as possible so it's air conditioning system - which is about the standard size one normally put into small RVs (13,500 BTUs) - can always be made to swamp out heat (BTU) gain from the outside through the RV's ceiling, walls, and floors. As some above have suggested, in our case we can block off the cab, cabover bed, and rear bed areas with curtains if necessary so the air conditioner's BTU removal capacity can keep ahead of all heat gain coming from the outside into the remaining small interior space.

For immediate "emergency type" cooling in extreme exterior ambient temperatures, we can block off the rear bed and cabover bed areas for more than 35,000 BTU cooling capability coming from both the rooftop A/C and V10 engine A/C. So far when parked we have not been able to budge the V10's engine temperature gauge while idling it long periods with the cab air conditioning set at full power in outside temperatures as high as 105 degrees. We haven't yet been parked in higher outside temperatures than that, however.

For the OP's situation in 115 degree heat, the heat gain rate of the RV is obviously ahead of their air conditioner's (current) BTU removal rate. The operation of their A/C can of course be checked/verified by comparing A/C entrance and exit air temperatues to make sure the difference is at least 20 degrees.

garyhaupt wrote:
In the years that I have been an RV Net member, I don't recall ever reading about A/C's shutting down due to heat issues. huh...I am sooo glad that I am not in Needles or Barstow or the Mojave right now.


Gary Haupt

Condition called High Head Pressure can cause a AC to shut down.
High head pressure is due to the lack of heat removal during the condensing process of the refrigerant cycle. The AC could be removing enough heat when it is only 95 but unable to remove enough heat at 115. If the coils on the roof are dirty or blocked this can cause High Head Pressure.
I have personally experienced generator shut down from high temps while parked and under high temp conditions I will leave the generator compartment door open and try to shade that area of the RV.

At an ambient temp of 115 you are doing good to get the inside down to 90 degrees. About 25 degrees differential.