AC’s will not keep Solitude 373 FB cool

**KirbyRVA** · 07-03-2019, 07:11 AM

This is a concern that I have with our 384GK. We last used it in early May in Myrtle Beach, SC and the system seemed to struggle in the hottest part of the day to keep the interior temp at 73 with outside temps in high 80's. We plan to add window awnings on the driver's side windows. I had hoped GD had provided wiring to the vent in the kitchen so a third roof AC could be added. We have two 20 amp unused breakers (one for washer and one for dishwasher) so I have power for a third AC.

**[email protected]** · 07-03-2019, 07:41 AM

Originally Posted by DaveMatthewsBand

I’ve always heard you can expect a “max” temperature difference of 20 degrees (outside to inside) from any RV air conditioning unit.

This is factually incorrect. It's a mis-quote propagated by too many in the RV world.

The correct information is this - if you take a thermometer and place one at an AC outlet IN THE AC AIR FLOW and another elsewhere to measure the AMBIENT IN THE TRAILER, the air coming out of the AC duct should be about 20F cooler than the ambient in the trailer.

As the ambient air cools, the AC coming out will run about 20F cooler than the ambient air in the trailer.

Yes, if the trailer isn't insulated well, it will take longer for the ambient air to cool, and it might never get VERY cool. Having more than one AC unit can overcome that.

In our case, it can be 100F outside and we can have our bedroom at 65F if we want to. When we return to our home base in St. George, UT, it can be very hot in the trailer and at or over 100F outside. I set all three units on to 74F and it will cool down to that quickly, then one or two units hold it there. We usually turn the bedroom to 70F at night.

**bertschb** · 07-03-2019, 07:54 AM

Originally Posted by [email protected]

In our case, it can be 100F outside and we can have our bedroom at 65F if we want to. When we return to our home base in St. George, UT, it can be very hot in the trailer and at or over 100F outside. I set all three units on to 74F and it will cool down to that quickly, then one or two units hold it there.

This is our experience as well. Even if the outside temps are near 100, the only time we run both A/C units is when we've been gone during the day and need to drop the temp quickly. The awnings really help to keep the temps inside lower than they would otherwise be so we deploy those early in the day as long as it's not too windy.

**KirbyRVA** · 07-03-2019, 08:26 AM

No question the awnings help, especially with the rather large windows in the curb side of the rig. We don't have the dual pane glass so I think adding awnings over my driver side windows will help a lot since that side of the coach gets the afternoon sun. Also, we don't have slide toppers. I would suspect those with slide toppers find it easier to keep the rig cool.

**Aridon** · 07-03-2019, 08:39 AM

You can expect around a 20 degree difference from the input air to the output air. The air is drawn from inside the RV so as the temp inside drops so does the input temp. Outside temps for the purpose of this comparison are inconsequential and anyone using that as an example doesn't know how the system works. There is a limit on how much the system can cool which is why there are multiple airs on these RV's.

One of the reasons we avoided solitude was only 2 airs and 2 axles on long, heavy units. We felt the times we'd have to settle on either CCC or being the temperature we'd want we would regret it. Forget it if one Air breaks in summer, totally screwed. I would have avoided Grand Design Solitude just for those reasons. NO reason for there to only be 2 airs and no third optional on a 40ft+ fifth wheel. If we skipped momentum for something else, we'd have used a different manufacturer. We liked the solitude floor plans, but not the price vs what you got (axle and air wise) and no option to fix it. I'm not trying to crap on anyone's decision, solitude is a good unit, just wasn't for us because of the above. Our needs and wants are different than everyone else's.

With 3 airs in S FL we are more than comfortable (could keep the Rv in the mid 60's if I let them all blast) but I've had to mess with the dump vs using the vents to even out the flow. What was happening is we'd dump towards the thermostat, it would shut off early and the impact on the rest of the RV was less cool was getting diffused, raising temps in other areas a bit. Once I got that sorted out it stays at temperature. The basics is to dump away from the thermostat and leave the other side closed. In our master bedroom we keep the vents closed. This forces air to the vents and keeps the thermostat from getting blasted and turning off early.

We can live with 2 airs, the temps will jump a few degrees at the hottest and I would just juice the air a little more earlier to build up a cool cushion for that period. Generally only two airs are running most of the time anyway but that third takes just gives a little bit extra.

Our Newmar, Dutch Star was not as well insulated as our Momentum. We have an easier time managing with 2 airs in here than we ever did in the Newmar and the air flow / comfort factor is way better. The Newmar had almost too much air conditioning (3 air with low ceilings) and you would get the warm and cold clammy feeling as it cycled.

Regardless you have a 2.5-3 inch walls in 100 degree weather with the sun beating on them. You are going to go through some cooling. No getting around it. Three units will always cool better and give you some room if you lose an air. We've full timed long enough to know not having 3 would be a deal breaker for us because that one week the stupid thing breaks it is going to SUCK.

I would add another air to your solitude and be done with it. No real reason it can't be done but will require some fishing of wire and duct work. It isn't a terrible difficult job; Find the support trusses, mark them, cut your hole, same with the ceiling inside and connect the duct work. You'll likely need to run romex to the panel and some 12 v for the thermostat and connection to the air but it really isn't as a bad as it seems. The biggest step is getting over the fact that you're cutting a hole in your roof. Get some eternabond and keep the extra roof membrane to seal the space around the air conditioner shroud.

**cookinwitdiesel** · 07-03-2019, 08:50 AM

The 15+13.5 in our S-Class were working pretty much around the clock this past weekend in mid 90s sunny weather while we were camping. We had the thermostat set to 72, do not think it ever actually hit that. I had the dump open on both units. It is what it is, if you want a house, get a house. A trailer will never cool as well or be insulated to run as efficiently as a house - you will be making some compromises to have a trailer.

**huntr70** · 07-03-2019, 01:40 PM

Originally Posted by KirbyRVA

This is a concern that I have with our 384GK. We last used it in early May in Myrtle Beach, SC and the system seemed to struggle in the hottest part of the day to keep the interior temp at 73 with outside temps in high 80's. We plan to add window awnings on the driver's side windows. I had hoped GD had provided wiring to the vent in the kitchen so a third roof AC could be added. We have two 20 amp unused breakers (one for washer and one for dishwasher) so I have power for a third AC.

You won't be able to run all 3 a/c units at one time with out an energy management system being installed also.

**Aridon** · 07-03-2019, 02:29 PM

Originally Posted by huntr70

You won't be able to run all 3 a/c units at one time with out an energy management system being installed also.

Why?

So long as the legs are properly loaded you shouldn't need an ems on 50 amp. Afaik the ems only sheds loads on 30amp as we've tripped breakers and have never seen load shedding on any unit at 50 amp. 30? Yes.

Without an ems you'll pull what the weakest breaker in the chain will allow.

**huntr70** · 07-03-2019, 04:58 PM

They run the EMS on the Momentum's with 3 a/c units for a reason. Your 2019 should have the EMS control in/near the hallway to the bedroom, unless you have a fairly new build where they started using the staggered start systems.

The 15K Coleman units can pull 18+ amps each when the compressors are running.

Same reason you can't run 2 a/c's most times on 30 amp.

**Aridon** · 07-03-2019, 05:28 PM

Originally Posted by huntr70

They run the EMS on the Momentum's with 3 a/c units for a reason. Your 2019 should have the EMS control in/near the hallway to the bedroom, unless you have a fairly new build where they started using the staggered start systems.

The 15K Coleman units can pull 18+ amps each when the compressors are running.

Same reason you can't run 2 a/c's most times on 30 amp.

What exactly is the EMS doing to allow 3 airs to run 50 amp service? Sorry I don't believe it is necessary.

18 amps x2 on one leg is 36 amps leaving 14 amps left on that leg.

The second leg would have 18 amps leaving 32 amps remaining.

What exactly is the EMS doing and why would it be required? I don't believe it is necessary, as there is absolutely nothing preventing those amps in the electrical system of a 50 amp coach.

The only time an EMS is shedding loads is if the coach is on 30amp. When hooked up to 50 amp service the EMS does virtually nothing and does not shed loads.