My air conditioner, although blowing cold, isn't cooling enough to keep up with the heat. I have a Coleman unit, not sure if it's 15000 or 13500 but think it's 13500. I was debating on replacing with a new 15000 then realized that the rear vent in the bedroom is pre wired and vented to add a second AC unit. Now I'm wondering if I should put in a new unit up front and move the old one to the rear. Just add a second unit in the bedroom. Or just replace the front AC. I'm also wondering if this is a DIY job or if I should have it done. With it being pre wired with a connector and breaker And having it vented into the duct work will both units run off the existing thermostat? I have 50 amp service so will I be able to run both at the same time and run off the generator? The generator is a 5500 with 50 amp service.

It depends on what thermostat you already have. If its an analog thermostat you can't add another unit to it. If its digital with two zones you can. If its digital with one zone you can't add to it either. The simplest and cheapest thing to do would be to add an A/C to the bedroom with an air box with a built in thermostat. Then its just hooking up the 110V wiring. If it is hooked up to the ducting, which I doubt, you'll have to tape up those outlet holes to use an A/C like this. You could add one to the bedroom with a thermostat on the wall if it is indeed ducted. It will have a digital thermostat which is an extra $100 and you'll have to figure out how to run the wire for the thermostat in the wall. The wire for these thermostats is basically a telephone wire with plugs on each end. It just plugs into the compressor and the thermostat. They don't even make a replacement A/C unit that works with the old analog thermostat anymore and if your replace one like that you'll have to put in a digital thermostat anyway. If you do that you can use a two zone thermostat and run both A/C units off of it. The thermostat will have to be in a central location where you can get the wires from both A/C's to it. I replaced my front A/C, which was ducted, with the unit with an air box. It had the old analog thermostat and I didn't want to fool with the installing a new digital one. It was a straight forward easy installation. the hardest part was getting the unit up on the roof.

I would add a 2nd unit if all is as described. Your generator is capable of running both. It's a DIY job if you are handy and the vent is already wired.

New one added. Replacing (even bigger) I have witnessed sometimes doesn't produce the desired result. It may be more of a circulation issue or who knows. Adding one directly there will fix the issue.

I went through the same dilemma as you. My 13.5K unit just wouldn't keep up on hot days. I too had the prep in place for a second ducted unit. In fact, the manufacturer included wiring for the thermostat by hiding it behind the bedroom light switch. I had mine installed, but it's relatively easy to install them. The big issue you might face is how to get it up on the roof. Those rascals are heavy.With the old single unit, I'd get up to 85-90 on a hot day here in AZ. With both units, I can easily keep the rig at 75 or lower.Jim

Replace existing AC or add 2nd unit in the bedroom

Mile_High
Explorer
Jun 08, 2016
The first time I added a 2nd AC, you just get the bottom diffuser trim with the controls and thermostat built in. There is no need to modify your original wall thermostat.
nemo45
Explorer
Jun 08, 2016
nemo45 wrote:
mpierce wrote:
I have a 90 Bluebird. The rear bedroom AC quit. The AC guy said the wiring and thermostat would need replacing too, as they are too obsolete for the newer ACs.
So, I put an Atwood AC in. It has a panel on it to control it, and it uses a remote. NO wiring, NO thermostat, just need the power feed.

Works great. More efficient that the oem too. That is what I would do. Nice to be able to lie in bed, and adjust the temp, turn off, etc. without getting up at 2AM!

This is really a good idea. I wish I would have put one in with a remote, and I think Dometic makes one too, as my wife is too short to reach the controls without a stool. We have 7-1/2 foot ceilings. So, anytime the A/C has to be turned on, off or adjusted I have to do it. Yes, I'm lazy. If I have to replace the other one that's what I'll do. Remember though, if you have a furnace running on the thermostat for the A/C It won't run without the A/C in the loop, because there is a 12V wire for the furnace that runs the A/C controller so they can't run at the same time. I had to put a manual thermostat for the furnace in. If you're just adding an A/C its not a problem.

Found out Dometic doesn't make one with a remote for the air box.
mike_brez
Explorer
Jun 08, 2016
falconbrother wrote:
Installing a roof AC is very easy, even the wiring is simple.. But, if your RV is a 30amp you don't have the power to run an extra AC unit. Two roof AC's are found on 50amp RVs. But, you could pull a second 15 amp circuit. I have done that an I ran a 15amp shore connection. Just be real comfy with your wiring and circuit breaker. For a second AC I chose an 11000 BTU and it was more than enough.

Seriously, the hardest part is getting the thing up there. I have done this job 4 times. If the wiring is there and you have the amps it's as easy as falling off of your RV, which you should avoid.

OP in his first post said he has a 50 amp service.
falconbrother
Explorer II
Jun 08, 2016
Installing a roof AC is very easy, even the wiring is simple.. But, if your RV is a 30amp you don't have the power to run an extra AC unit. Two roof AC's are found on 50amp RVs. But, you could pull a second 15 amp circuit. I have done that an I ran a 15amp shore connection. Just be real comfy with your wiring and circuit breaker. For a second AC I chose an 11000 BTU and it was more than enough.

Seriously, the hardest part is getting the thing up there. I have done this job 4 times. If the wiring is there and you have the amps it's as easy as falling off of your RV, which you should avoid.
nemo45
Explorer
Jun 08, 2016
mpierce wrote:
I have a 90 Bluebird. The rear bedroom AC quit. The AC guy said the wiring and thermostat would need replacing too, as they are too obsolete for the newer ACs.
So, I put an Atwood AC in. It has a panel on it to control it, and it uses a remote. NO wiring, NO thermostat, just need the power feed.

Works great. More efficient that the oem too. That is what I would do. Nice to be able to lie in bed, and adjust the temp, turn off, etc. without getting up at 2AM!

This is really a good idea. I wish I would have put one in with a remote, and I think Dometic makes one too, as my wife is too short to reach the controls without a stool. We have 7-1/2 foot ceilings. So, anytime the A/C has to be turned on, off or adjusted I have to do it. Yes, I'm lazy. If I have to replace the other one that's what I'll do. Remember though, if you have a furnace running on the thermostat for the A/C It won't run without the A/C in the loop, because there is a 12V wire for the furnace that runs the A/C controller so they can't run at the same time. I had to put a manual thermostat for the furnace in. If you're just adding an A/C its not a problem.
willgrab
Explorer
Jun 08, 2016
OR, how about a mini split ac, very low wattage requirements and sooo quiet you wont know when it is on
Mile_High
Explorer
Jun 08, 2016
If you are prewired - go for a 2nd AC. Your 5500 is more than adequate. We ran two 1500 btu ACs off of an Onan 5500 on the last three fifth wheels.
mike_brez
Explorer
Jun 08, 2016
TNGW1500SE wrote:
First I'd figure out if the old A/C is running 100 percent like it should be. If not, I'd get that one up to speed. If that wasn't the case, I'd look for ways to insulate and/or shade the RV. If all that fails, I'd add a second A/C unit. It would take me a few drinks to get the nerve to cut the roof. I would want to know exactly where to cut and defiantly cut from the inside first. It something went wrong, I could fix the interior. I'd make sure the wiring was there before cutting the roof! I'd probably DIY the job but that would be one I'd hate to tackle! There's a bunch of stuff that could go south on you. Like at said at the beginning, make sure the old unit just doesn't need a little TLC first! You could always just drive north!

No need to cut a hole in the roof the roof vent is allready there that's were the a/c goes and he said the wiring is there also along with duct work.
mpierce
Explorer
Jun 08, 2016
I have a 90 Bluebird. The rear bedroom AC quit. The AC guy said the wiring and thermostat would need replacing too, as they are too obsolete for the newer ACs.
So, I put an Atwood AC in. It has a panel on it to control it, and it uses a remote. NO wiring, NO thermostat, just need the power feed.

Works great. More efficient that the oem too. That is what I would do. Nice to be able to lie in bed, and adjust the temp, turn off, etc. without getting up at 2AM!
nemo45
Explorer
Jun 08, 2016
Vt Rv wrote:
I have a Kabota with a front the loader. Getting it up is the easy part, no pun intended!

We used a John Deere 25 hp diesel with a bucket up front but it was still about 3 ft. short so had to pull it up 2 X 6's with a rope.

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Replace existing AC or add 2nd unit in the bedroom

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