Class C Roof Top AC replacement suggestions

[JollyCamper]

So, the time has come to replace the 40 year old AC unit on our rig. Plugged in to check everything in anticipation of our Labor Day trip, and nothing but warm air from the AC. One of my employees is an HVAC Tech, and we pulled the cover and checked things over. Haven't actually tapped a line to check pressures yet, but we are almost certain the freon charge is low. We have a hair brained scheme to get the AC to work for the short term, but replacement is going to be needed. I don't mind spending the money, we are nowhere near the end of our ownership of the rig, and AC is mandatory in Texas! I was just wondering what you guys would suggest for a replacement unit. There are many, many options out there! There is a particular DuoTherm unit I have looked at and the price is definitely good, but I am unsure. I currently have an old Dometic 13.5 unit. We have a 27' Class C, so would it be justifiable to go ahead and upgrade to a 15K unit? Any and all opinions welcomed, especially from anyone who has replaced a unit!

[vito.a]

I just installed a new Dometic AC unit on our RV. It was about $100 more for the 15,000 btu so went for it. I purchased it from PPL Motorhomes (they periodically runs sales).
You will need to be concerned about thermostat compatability. If your thermostat has not been previously replaced, you will need to this time.
This is a "How To" I did on replacing it. This is on a class A, but a lot of it is still applicable.
http://www.irv2.com/forums/f115/repl...ch-405503.html
Best of luck!

[JollyCamper]

I guess I should have included all info...non ducted unit...ceiling controls and vents, no heat. I am looking at the DuoTherm Brisk Air 2. Then I noticed the Dometic Brisk Air 2...guessing they are the same. Would one be better than the other?

[Old Crows]

Bud.... after 40 years of use, it doesn't owe you anything. Just get a new one!


Yes, go for 15K BTU. Get the hugest BTU and lowest current draw you can find.

[JollyCamper]

Vito, was there a noticeable difference in AC performance when you upgraded?

[vito.a]

Yes, Dometic is the manufacture's name and Duo Therm is the model lineup for their RV air conditioners.
They sell the Brisk Air II (full height), the Penguin II (low 9 1/2" profile), and the Blizzard NXT (new generation AC). Most of these are available in 13,500 or 15,000 BTU and then they also make them with heat pump options by adding a reversing valve. Another option is to add a heat strip to one of the regular AC units (although these are not very effective).

Also yes. I do notice a difference in the 13,500 and the 15,000 BTU AC units. The air coming out of the 15,000 is 47 degrees and although I cannot measure the air flow you can feel a difference. The 15,000 cools down faster and then cycles off a few minutes before the 13,500. Now I wish I had ordered two 15,000 BTU units!

We live and travel in the southwest where it's very hot in the summer, so AC performance is very important to us. If you live in a mild climate the 13,500 will work fine.

[Old Crows]

Originally Posted by JollyCamper

Vito, was there a noticeable difference in AC performance when you upgraded?

We had a Class B that came OEM with 9.2K BTU. Not satisfactory. CW upgraded us for free to a 13.5 BTU. Satisfactory. So, my advice is to go with a 15 or slightly higher (that you can run on 30 AMP service).

You can always turn the thermostat higher to make it warmer. If it's not cooling... you can't turn the thermostat 'lower' to get more cool out of a 13.x BTU unit. That said, you need three things: as much cooling BTU (desert ratings! that should be on the spec sheet), lowest amp draw on starting and continuous operation (most efficient), and, highest CFM on the fan (because with a single outlet roof unit you need air circulation in addition to the BTUs.

Todays units are 'one size fits all' on installation. But check the size of the opening in the old unit to be sure.

We have a Coleman Mach 8 on our View. Does a good job but noisy. If you decide its for you, PM me. I have a couple 'mods' that will make it quieter.

[JollyCamper]

Well, an update on my AC situation. The non functioning was the result of no refrigerant. Long story short, the leak has been found and repaired, bullet piercing valve installed, vacuum pulled, oil charge injected and I charged the unit with r134a. It is originally an r22 unit.
I know this may not be a gamble for everyone, but we need to squeeze 1 last weekend out of the unit and then I can look into replacement. I don’t think the performance is as good as originally, but I am getting 60 degree vent temp, and it is the quietest the unit has ever run! From inside you can barely hear the compressor running. It is odd ball, and not for everyone, but it will do for the pinch.

[leadman]

Don't know if you have a generator and run the a/c with it or not but here is something to consider:
The new 15k units seem to draw more power than the older ones. Could be because they are made in China? Some problems have been noted on MHs with 2 units on them. Several people have replace 13.5K units with 15k units and now have issues running them with the generator. One member had the shop that installed the 15k unit replace it with a new 13.5k unit.
My coach has 2 a/c units on a 30 amp service. This works because both units are Coleman Power Saver units which cost a couple of hundred dollars more but only draw around 8 to 9 amps each. They are 13.5k units.

Just something to consider before making your purchase.

[Charles M]

I replaced both of my roof air conditioners last month (Aug 2018) and the whole job was an hour or less. I picked Coleman 13,500 Btu Power Saver units from PPL Motor Homes.
https://www.pplmotorhomes.com/parts/...pwr-savr_63152
It is something I wish I had done when I first got the coach! They work great, and cool better than the aging units they replaced. They have great airflow, at 330 cfm I believe. The downside to moving that much air is that it creates noticeable air noise. I did upgrade the inlet/filter assemblies to a chill grill because I have a ducted system and it is nice to have even more contol over the airflow. It has better filters too, no screws to remove to clean the filters! I did have to move the light assembly near the front intake because the new grill is a bit larger. But now the drivers position gets at least some roof air conditioning which it did not before!
https://www.pplmotorhomes.com/parts/...llgrille_66002
What I am trying to say is, replace your air conditioner rather than trying to keep a unit older than about 8 years old. By the time you do service the freon, you could have replaced it with a new unit.

[JollyCamper]

I will look into the power saver units. My leak repair failed about an hour into the trip, so definitely looking to replace soon.

[Reysol]

I actually removed both roof units on my class a, replaced them with super quiet mini splits. The wife loves the sunlight coming in from the new roof vents where the ac's used to be. The units are so quiet outside, the neighbors don't know when they are running. Not the most common replacement, but it was an option since we were remodeling the interior

[1320Fastback]

I yanked the 2 year old Dometic off my Toy Hauler and replaced it with a AtWood AirCommand.

This new Australia built AC is so quiet and moves air so much better. I can feel a cold breeze on the front bed even though the AC is in the back of the trailer. With the Dometic we had to have a household box fan to move air forward.

It uses the standard 14x14 opening and took less than 1 hour from start to finish to install, including removing the old one.

Running on 15A house power last weekend in Temecula, Ca with a outside air temp of 105F it was 70F in the trailer (under huge car port in shade) and may of gone lower but that's where I set the built in thermostat.

[spyderRV]

Originally Posted by Reysol

I actually removed both roof units on my class a, replaced them with super quiet mini splits. The wife loves the sunlight coming in from the new roof vents where the ac's used to be. The units are so quiet outside, the neighbors don't know when they are running. Not the most common replacement, but it was an option since we were remodeling the interior

I have mini splits at my home, how did you install yours? Pictures?

Thanks