Need more air power. RV AC question.

[Tuesdak]

Working with a 2003 Arctic Fox 27-5L 5th wheel. 27' length hitch to bumper 25' living space with one small and one large slide. Assumed 13.5K BTU standard Coleman Mach AC. 30 Amp service with 3600W LP Onan.

Most of the time boondocking in cooler locations AC isn't needed, however, I am experiencing the need for AC in hot locations. On the way to cooler locations with overnight stays in hot locations. Loading the RV at home where it's 110+ degrees hot is a good example and only have generator power to do that with.

First step was locating to cooler locations of 95 degrees vs. 108 at home. Regardless I am only getting a 9-10 degree drop from the 95 degree outside temps. Ran AC for 2 days straight. Pulling the slides in didn't make a difference and blocks the living room ducts.

Foam divider is in place in the ducts. Coils clean.

Do I:
1) Replace the 13.5K BTU with a 15K BTU?
2) Add a bedroom AC on a separate 20 amp plug. 50 amp plug with 30/20 amp breakout appears common. (I doubt the existing vent hole is braced for AC.) If so what BTU size should I look at?
3) Look closer at the 2003 OEM 13.5K BTU unit not working properly?

With the newer more power efficient AC units could I replace the old one and add a second one while staying with a 30 amp supply let alone within the limits of the 3600W LP Onan? (LP use is the least of my concerns.) Generator powering both AC's, and only AC, is a secondary goal.

What is needed/involved for the extra bracing to add a second AC to the bedroom on an older "wood framed" Arctic Fox?

 

[wyosteve]

Just my guess, but I'd say your AC needs replacement. I have an '06 Arctic Fox 24-5, so a bit smaller than yours. One medium slide. In 95+ temps, the air is so cold throughout the unit that I have to typically turn it off at times. Gets down into the 60's easy.

 

[6V92TA]

have you placed a thermometer in the AC outlet and measured the temp coming out?... if its blowing relatively cold air in those ambient temps cold, its just a matter of needing more capacity than you currently have.. honestly, I lived in my 32 foot 5er for a year in SFLA, and we were doing good if we could keep it slightly below 80 on the inside on the bad days..

 

[GAmes]

I special ordered my Fox Mountain with a 15k AC, it is a NorthWood product too. Even with one slide it will not keep the camper cool so I found a lightweight AC used in slide in campers and installed it in the front vent opening over the bed. I ran a supply wire as hidden as possible to the outside and installed a separate receiver that a 20 amp extension cord will plug into. Problem solved. I keep telling myself that one day I will remove the cover from the main AC to verify the vents are connected and not plugged since the AC has never worked very well.

 

[Cummins12V98]

IMHO two AC's are always better than one. One goes bad you still have some cooling. Our 40+' DRV has three units and it cools great in temps to 122. Two units would be a NO go.

 

[Tuesdak]

As suggested my next step is verifying it has around a 20 degree drop from the intake to the outlet. I feel it will just tell me I need more capacity. Possible it's weak, but, it feels cold and I have water dripping off the roof from the AC.

I read installing a second in the bedroom is a height concern to stay under 13'6". Aka low profile units. I could install a second unit in the living room and this gives me more choices of high efficiency units with the Coleman Mach 3 P.S. 13.5k BTU. Atwood Air Command appear to be the 'never shut the damn fan off' designs, but offer efficient 15K BTU options. At 1440 'dessert temp running watts' I could run a pair of the Coleman Mach 3 P.S. on the gen-set with enough room for the fridge on AC or de-rate of the genset.

Although I will hire out lugging the 100# AC units up to the roof I am curious as to what has to be done for additional bracing for an AC unit in the roof? As in how big of a job is this gonna be?

 

[GAmes]

You could always contact NorthWood and ask them about the opening. Chances are it doesn't need any reinforcing.

 

[6V92TA]

most newer fivers are pre wired for a second AC even if they don't have one installed in the hatch.

 

[GAmes]

Today I investigated why the 15,000 BTU AC in my trailer cooled so poorly (I've only had the trailer three years). In the Coleman there is a divider between the air being pulled into the AC out of the RV and the forced cold air back into the RV. It is about 1/2 inch thick and is not fastened. It is up to the installer to place it and secure it. Instead of being vertical mine was at about a 45 degree angle. So the air being pulled into the AC was partially (maybe mostly) the air being sent to the vents. That explains why there was very little air being sent to the forward vents in the bedroom. I used a quantity of gorilla tape to secure the divider in place and to seal the edges. The amount of air being sent to the forward vents has increased substantially and the temp was over 40 degrees cooler than than the interior of the RV. I'll find out on the next trip, but I might have bought and installed a 2nd AC needlessly. So much for NorthWood trailers high quality builds.

 

[DavidC]

The divider leaking is usually a cause for freeze ups also.

Dave

 

[GAmes]

Today the temp was 90, the inside of the RV was 94. I turned on the AC at 3:00 and in an hour the inside temp had dropped to 84. Previously it would take until the sun set to get the temp to drop that far.

 

[DavidC]

Sounds like you fixed it. Currently in Az. it is 98 outside and 74 in the 5ver. Since I am kind of held hostage here with health issues I hope it cools this well during the average 110-115.

Dave

 

[GAmes]

Sounds like you fixed it. Currently in Az. it is 98 outside and 74 in the 5ver. Since I am kind of held hostage here with health issues I hope it cools this well during the average 110-115.

Dave

With that much temp difference your AC is doing a lot better than mine did when temp were in the high 90s.

 

[DavidC]

This one has the Quck Cool option that has the doors that open straight down from the AC at the intersection of duct work and Quick Cool. With that open some air still goes thru the duct work and registers but most comes out the doors. If I let it go thru the Duct Work it does not work quite as well. The drawback coming out the doors is more noise with all the air movement. I close the doors and use the duct work at night.

Dave

 

[ringneck]

be sure and blow the radiator out on the air,dust and bugs not good

 

[Tuesdak]

I thought I had updated this... Although the divider was in place I stuck my hand into the intake to see if there was a small air leak from the roof ducting back into the intake. Took me a moment to figure out what I was feeling: basically an "air knife" coming between the divider and the grille bolted to the ceiling. So I am thinking small leak and feel an air knife from a massive leak.

Black on black it's hard to see the actual air gap here. You are looking in the AC intake at the foam divider.

Pipe insulation foam wrap applied here. Silver tape being applied over "minor" duct leak back into intake.

Intake Grill re-installed and could use some tape to further seal it. Duct Tape isn't good enough here so I am using aluminum tape with some real 3M adhesive backing.

 

[Dan_69GTX]

When we lived in AZ the A/C always worked to cool the camper just fine. We also installed a vent that allowed the air to be dumped right in the main cabin instead of through the roof vents - that helped the initial cool down, then close the vents for the air to be dispersed.

 

[Tuesdak]

Just my guess, but I'd say your AC needs replacement. I have an '06 Arctic Fox 24-5, so a bit smaller than yours. One medium slide. In 95+ temps, the air is so cold throughout the unit that I have to typically turn it off at times. Gets down into the 60's easy.

Thanks. This helped me look harder at the AC system. I had the AC on this weekend. Started from 100 inside and 20% humidity. It was 104 out and 73 inside after a couple hours. Setpoint of thermostat... Before just a 10 degree drop over outside.

 

[DavidC]

Sounds like you did a great job sealing the holes.

Dave

 

[Tuesdak]

Do I:
1) Replace the 13.5K BTU with a 15K BTU?
2) Add a bedroom AC on a separate 20 amp plug. 50 amp plug with 30/20 amp breakout appears common. (I doubt the existing vent hole is braced for AC.) If so what BTU size should I look at?
3) Look closer at the 2003 OEM 13.5K BTU unit not working properly?

So a long term update:

I added a second 15K A/C by moving the 13.5K to the bedroom as I have plenty of height on this older shorter height RV. 13' now with full height A/C over bedroom. Absolutely no measurable difference in performance between the 13.5K and 15K BTU (with just the one A/C on in living room). 81-82F inside during the heat of the day ~4PM after running one all night. Turn the second A/C on and it's a world of difference esp. in 105-117F. Get 71F in the bedroom at will in these temps. ~78F in main area during heat of the day.

The bedroom A/C is on a separate 20A plug. So I have a 30A RV plug and a 20A plug now. The 3600W generator will not power both as they take ~2KW each in desert conditions.

The 13.5K needed service as some air deflectors for the condenser turned to dust and were gone on this 21 year old RV. Also got a new fan motor as it was tight to turn and getting noisy on startup.

I went with a 15K RecPro that has a heat pump. It lives up to being very quiet and worth the trouble. Saved me lots of propane when the RV needed heat overnight. However no labor warranty, just parts, as I found when a control board failed. Also it runs the fan inside all the time stupidly blowing the humidity back into the RV when the compressor cycles off. I just set the temp lower to keep the compressor on and shut the entire unit off when it's cold enough. The Coleman on the thermostat would completely cycle off. Again as the RecPro is saving me propane and extremely quiet over the LOUD Coleman it's worth it.