ANOTHER AIR CONDITIONER ?

[JIGGS]

CAN I GET SOME HELP ON THIS.  LAST SUMMER WHEN THE TEMP WAS IN THE 90's OUTSIDE. THE TEMP INSIDE WAS JUST AS HOT. I CAN ONLY RUN ONE AIR AT A TIME. IT GOT SO HOT THAT I SHUT THE BEDROOM DOOR IN THE BACK AND THE TEMP JUMPED OVER 100 IN THE BEDROOM.  STILL THE FRONT STAYED IN THE 90's  I KNOW WE WERE NOT IN A GOOD SPOT. NO SHADE NO BREEZE NOTHING BUT HEAT. I SAID THE FRONT AIR NEEDS RECHARGED OR REPLACED. IF IT WAS WORKING GOOD IT SHOULD OF BROUGHT THE TEMP INSIDE DOWN AROUND 15DEGREES LOWER THAN OUTSIDE AIR TEMP.ESPECIALLY WITH THE BACK DOOR SHUT. I WAS TALKING WITH A GUY I WORK WITH AND HE SAID THE AIR IS WORKING FINE [he has not looked at it] YOU MUST PARK IN SHADE OR YOU WILL NEVER KEPT IN COOL INSIDE. THERE IS NO SHADE AT THIS PLACE. ALL I CAN DO IS PUT THE AWNING SIDE IN THE SUN.
HAS ANYONE ELSE RUN IN TO THIS PROBLEM OR HEARD OF THIS ?

 

[Tom]

If it's any consolation, I have two friends who are about to trade their 2-3 year old coaches because the two a/c units can't keep their coaches cool; Their new coaches will have 3 a/c units. Their home base is Las Vegas.

One a/c will have a tough time cooling your RV down when it's 90 degrees outside, although it depends on how much volume you're trying to keep cool. Your friend/colleague offers good advice - parking in the shade will help considerably. If there's a lack of shade, awnings help by keeping direct radiation off one side of your RV.

 

[BruceinFL]

I live in FL and have no problem cooling my 31 ft fifth wheel with my one and only 13500 BTU AC. Never had a problem with any of my other RVs either. Stick a thermometer directly in the outflow of the AC and see what temp the air outflow is. My bet is the AC is bad.

 

[Ron]

What color is your roof.  Some manufacturers have painted the roof a dark color and in some cases even black.  Dumb move since the dark colors will increase the heat load tremendously to the point where a coach that could be cooled with two Air conditioners with a white roof could require three of the same capacity to cool a coach with a dark roof.  Some manufacturers have seen the error of their ways and have repainted the dark roofs at no charge to the owner.

 

[Tom]

Good point Ron. I didn't think about the roof.

 

[Gary RV_Wizard]

You didn't mention where you were, outside temps or anything like that.  I've had trouble keeping the interior below 80 degrees when parked in the full desert sun at 100+ outside. What was you like where you were? We put sun shades in our skylights (we have five skylights besides the a/c units) and that makes a huge difference.  Opening the awning also helps by shading one side a bit.

Many Rvs are not well insulated and some have lots of glass in walls and roof.  Older ones especially.  What about yours? Does it have dual pane glass? Good sidewall and roof insulation?

Regardless of the answers to these questions, I would think you could cool the front to under 90, probably something in the low 80's any rate.  With good insulation and dual pane glass it should get much cooler than that. Have you placed a thermometer right at the a/c outlet to see how cool the air actually is?  An a/c unit can cool the air flowing through it about 15 degrees. This doesn't mean the whole room will get to 15 below the outside tep though.

 

[Tom]

A couple of other things we do to reduce direct radiation:

• We have exterior screens for the windshield and adjacent windows.
• Normally used while in storage, but sometimes used when we're camped - we have interior screens for the other windows.

 

[Jeff]

Our first Pace Arrow had a split electrical system that would only allow one air conditioner to run while pugged into shore power but both on generator.

When temps wentr over 90 we had to:

1. close off bathroom and bedroom
2. keep shades pulled
3. Start a/c early in the AM to keep ahead of the heat.

If we started after it got hot we would start generator to run both a/cs until it cooloed off.

There is also a load shedding system that can be installed to allow you to run both ac's but it only allows one compressor to start at a time.

 

[Karl]

Another thing you can do is place some panels of that silvered plastic bubble-wrap type materials in the window openings. May not be the most aesthetically pleasing, but neither is standing in pools of sweat. Window tinting can also be applied if you don't already have it, but be sure to have them use only the type approved for dual-pane windows. The regular stuff can damage them. Don't think it matters for single-pane windows.

 

[Tom]

...be sure to have them use only the type approved for dual-pane windows. The regular stuff can damage them.

An expensive lesson I learned at our last house.

 

[JIGGS]

THANKS AGAIN FOR YOUR INPUT.  JEFF I TO HAVE A 89 PACE ARROW 37 ft. MOTOR HOME.  I HAVE STARTED THE AIR WAY BEFORE IT STARTED TO GET HOT OUT. CLOSED ALL BLINDS AND TURNED ON THE MAX AIR FAN.  I WILL CHECK THE AIR COMING OUT. IS THAT AIR TO BE 15 DEGREES COOLER THAN THE AIR OUTSIDE ?  I LIVE IN PA ON THE STATE LINE WITH OHIO.  THE WINDOWS ARE DOUBLE PAIN. THE ROOF COLOR IS TAN . I HAVE HEARD OF THE WALL SIDES NOT WELL INSULATED. I KNOW IT'S AN OLD MH BUT I TAKE MY MOM CAMPING . SHE IS IN HER EIGHTY'S AND LOVES IT. WANTED TO TRADE IT IN BUT NOT WITH OUT A FIGHT WITH HER. SHE IS ON OXYGEN ALL THE TIME SO I HAVE TO COOL THE MT DOWN. THANKS AGAIN JIGGS
P.S.  THIS IS WERE I THOUGHT ABOUT HOOKING ONE AIR TO IT'S ON  LINE FOR POWER. THEN I COULD RUN BOTH AIRS

 

[Karl]

Jiggs,

Yes, it should be around 15 degrees cooler than the outside air. You could run one of the a/c's from shore power, but that would require you to remove it from the coach wiring and connect it directly to an extension cord with a quite large wire size; at least a #12, #10 would be better, and keep it as short as possible. Unlike automotive air conditioners, roof-top a/c's are sealed units and won't require a recharge unless there is a leak somewhere in the system which would have to be fixed first, such as a broken refrigerant line or expansion valve. If you're not getting a 15 degree difference between outside air temp and the temp of the air at the outlet of the a/c, check the obvious problems like a dirty/clogged filter inside, leaves or other debris blocking the air flow thru the condenser (located on the roof), a bad condenser fan (pushes or pulls cooling air thru the condenser), or low line voltage. Anything below about 110 volts can cause the a/c to operate at less than full capacity. You also said you run your MaxxAir fan. For best operation, this should only be done to exhaust the hot air inside the coach, then shut it off so your'e not sucking out the cool air from the a/c.