[Archived]

I’ve had the same problem in the past Bill, the intake air is just so hot they can’t cool as needed. Couple of things, raise the bus up as high as you can for more airflow and I hosed down the concrete with water under the bus to help cool the intake air. After going to roof airs, I would never go back.

Now Jon won’t agree with me, he’ll tell you he’s not had that problem in 55 years of busing, but just remember, he never travels in the summer while his garden is growing and the yard rats are having a feeding frenzy.

[Archived]

I agree with Tom. I have had both and the cruiseairs were always problematic if it got too hot. Raising the bus, and wetting down the concrete or whatever under the bus does help. My last coach had the bedroom evaperator changed out to a larger one and that did help some.

I have roof airs now and have had them before. I will never go back to cruiseairs if I can help it. The roof airs are much more efficient, and the newer units are not as noisy as the older ones were.

[Archived]

I have the rvac system with two cruisairs and with all 3 units running in the Florida heat best I can maintain is 75-76 degrees can’t get it any lower than that until after 5-6 p.m

[Chad]

With my basement AC on I am using approx 30 Amp’s (2 compressors running @ 15 Amp’s each), turn on front Cruiseair adds approx another 15 Amp’s for a total of approx 45 Amp’s. As we all know a 50 Amp breaker at most parks do not handle a full 50 Amp’s. So add the house refrigerator, the basement refrigerator, and a few more Amp’s for the charger/inverters and presto you over the parks breakers maximum Amp’s.

Other than the basement refrigerator all these items are essential items. How are others dealing with the power management needed to keep the AC units (more than one unit) running?

Also: has anyone attempted to add more insulation to the front cap area of the H3? There is a LOT of heat coming from the front cap area even with all the front blinds closed.

Chuck

---

1984 96" with 8V92TA

(remodeled Liberty Coach)

Greenwood, MO

[David]

Chuck, CA’s require a lot of relatively cool air flow. Working against their efficiency are a few things. Liberty installs baffles beneath the coach to direct air flow so the air for cooling the condensing coil is not the heated air coming from the units. The baffles need to be undamaged, and maybe even removed if they are restricting air flow.

The second problem, and this is a huge one, is the windshield. Liberty has installed black privacy shades and if the coach is facing in a southerly direction the sun acting on those shades is generating more heat inside the front of the coach than any combination of CA’s can handle. Point the coach north, or get rid of the black shades and change them to white or a light color.

Advice about keeping the coach raised a little is good advice and wetting the surface under the coach cools that surface until it cools down by itself in the shade under the coach.

If the coach gets warm it is not only the air getting warm, but all surfaces in the coach. Try to get ahead of that by making use of OTR. Start the bus and let the OTR pull down the temps until surfaces are cool. That way it is easier for the CA’s to maintain temps rather than have to work to cool down the many pounds of warm interior surfaces.

Your CA’s are on two 50 amp legs, so if you reduce other loads you will have about 30 amps of current draw on each leg. Just remember you cannot control when the HW tank, aux compressor or some other items will kick on and add to the load so while running all A/Cs be aware you may not be able to have all circuits on.

[DON]

Re coat the roof with Hy-Tech Bus Kote , Huge difference !

[AL]

For power management add soft start to your units. For more cooling if the units are charged correctly only thing to do is add external fans to condensing unit to assist in air flow.

[John]

A 50 amp park breaker will handle 100 amps. Yes, that’s right. A 30 amp breaker can handle a total of 30 amps. A 50 amp breaker can handle 50 amps ON EACH LEG for a total of 100 amps.

[Jim]

On my last 2 Marathon’s coating the roof made a big improvement.

If you have a bus with Valid slides the top of each slid out can be coated. Marathon service centers use a premium spray product when applied thickness is 2 business cards together.

AL

[Archived]

Hello,

I went to Home Depo and bought reflective 3/4 insulation board. Cut it and put in the 10 Salon and Kitchen windows of my XL…..it made a big difference in the temperature. Only drawback is not being able to see out the windows, but with it 95 outside and supposed to hit 100 soon, I would much rather be cool.

David Thomas

1998 Featherlight XL

[Larry & Diane]

Jeff:

I have bus air so I only use the CA when stationary. I was thinking of installing a electric fan just behind the front bumper grill that would run when the CA was turned on. Have you done that or have you seen it done?

Chuck

[John]

To cool and maintain cool temps in any coach regardless of the type of house A/C units being used there are certain things that are going to help.

The first an owner has no control over the number of A/C units used. Entertainer coaches typically have 5 roof air units. Given normal BTU ratings of between 13,000 and 15,000 per unit there is up to 75,000 BTU of cooling power available.

As a reference point OTR systems range in performance from 80,000 plus on older 40 foot coaches to over 100,000 on newer coaches.

Motor homes typically have 3 A/C units on 40 foot coaches (up to 45,000 BTU) or 4 A/C units on 45 foot coaches, (up to 60,000 BTU).

The message here is simple. Trying to cool a heat soaked coach using only house A/C units is a challenge, and in some cases with strong sunlight, high ambient temps, and single pane coach windows it might not be possible to adequately cool a coach interior because the coach does not have the needed cooling power.

The first and likely most important step in cooling is to not allow the coach interior temps to rise. If traveling, use as much A/C power as available, including if required OTR, driver’s air combined with converter installed air, and if required as many house air units as required.

Keep sunlight out of the coach. The sun is going to heat up surfaces it hits, so block it with shades or awnings. Especially avoid black shades. A black shade in the windshield, with the bus pointing toward the sun will throw so much heat into the coach no house A/C unit will overcome the heat generated by the shade. It is like running the Webasto while trying to cool the coach.

In the case of Cruisair units cool air is especially important. Unlike roof airs which have little in the way of obstructions CA installations are usually buried deep within the underside of the coach and may not have ample unrestricted air flow to or from the CA condensing unit. So it is important to make sure the intake and exiting air flows are not affected by dirty coils or bent deflectors. Also insure if there are baffles needed to keep hot exhaust air from being drawn back into the air intake that they are where needed.

When ambient temps are high all condensing units lose efficiency. In the absence of cool air larger condensing fans might help. At least one Prevost owner solved his problem (he was from Nevada) by using a pressure switch in the high pressure side of the condensing unit to trigger water misters that sprayed on the condenser coil. That is beyond what most would be willing to do but is a solution when all else fails.

There have been endless debates about OTR, or no OTR, converter installed systems they call OTR, roof airs, Cruisairs and some bay mounted 26,000 BTU units. But we get what the converter installed unless we spec the coach ourselves, and even then keeping a coach cool may be a challenge. Add to that each owner’s definition of what is a comfortable temp.

[Chuck & Katrina]

Jon:

You are spot on about getting the bus cooled down with the OTR then the CA and basement units don’t work so hard upon arrival at your destination. The problem I am having is the next couple of days while at a park I am depending on just the CA and basement units, and they are having an issue keeping up when there is no shade around and I can not run all the units because the park power will not handle it.

Chuck

---

2000 Featherlite H3-45

2024 Jeep Grand Cherokee

Leesburg, FL

[Jeff]

Chuck: I’m doubling down on previous posts about the available amps on shore power.

We should all have 240volt 50amp shore power RV plugs. Four prongs. Those are designed to give us TWO 120 volt legs of 50 amps each. Total of 100amps available.

But each leg is limited to 50amps. Your converter should have balanced the loads so that if you have four cruise airs, two are on Leg 1 and two are on Leg 2.

Tom mentioned water heater and aux air compressor. If I know I’m pulling lots of amps and I don’t need the water heater or the aux compressor I’ll turn them off.

One of the best Coach toys I bought was a Progressive Electrical Management System (EMS). Protects against power surge and low voltage. It also provides digital read out of the voltage, amp draw, and Hz on EACH leg. That way you can show campground manager that their breaker is tripping at less than 50 amps. Then the campground can replace the breaker or in some cases just tighten the contact points back to the main service panel.

I’m not an electrician or electrical engineer … but I faithfully read the Prevost Community Forum daily, read and post to Garage Journal Forum when I need help, and have a Liberty Coach. I understand there is a rule of thumb that we shouldn’t use more that 80% of a circuit’s capacity continuously. So try not to draw more than 80% … 40amps per leg of your shore power. I’ll let the educated and enlightened explain why.

If the campground won’t give you the power you need, fire up your generator. There are lots of amps just sitting there … waiting.

[Roy]

Hi Dick:

I too have the EMS system. Great to be able to check the Campground power before you turn the breaker on in the coach. I am currently in full sun and did have one leg at 42 Amps and the other at 29 Amps (Front CA and secondary compressor “basement unit” plus fridge and a few other things are on the high Amp line) confirming your input of 50 per leg for a total of 100 amps

Chuck

P.S. Dana @ AAP told me to run the fan at medium not high and the unit will cool probably another 5-8 deg cooler. It works