Will getting a larger roof A/C solve the problem?

Have you looked at all of the ducts and return air divider? My 13,500 and probably most ac units have a piece of cheesy baffle between the intake and outlet sides of the ac unit. When you remove the grill you will be able to see where the cool air comes out and the warm air goes in. The tape was falling apart in mine. The other thing that I found was the tape was deteriorated at the outlets and blowing cold air into the ceiling/roof cavity. I used spray foam to seal those areas but be careful or it may flow out and drip onto the floor.

Yes, more BTU"s means more cooling. After 24 years it does not owe you anything and if you use it during the winter in Fla I would go with a heat pump unit. I doubt it's a ducted unit. Something like ......like this.
This guy is in New Port Richey and has ...one that he might help you install for the same priceif you go to him.

Certainly, but before making the plunge check a few things.

1. Take down the lower unit (the ceiling fixture inside the coach) and with a flashlight check the fins of the interior heat exchanger. Even with the air filters a lot of debris will get past and coat the fins and degrade performance.

2. Get up on the roof and remove the cover. Clean the fins and the external unit plus check the fins. If the soft aluminum fins are bent do your best to comb them as best as possible.

3. As best you can seal the interior duct work. While doing #1 above check to ensure minimal leakage between the intake and exhaust. Use aluminum tape to seal.

I have the same thoughts as Ivylog with regards to a heat pump. A heat pump will cost more but will give you more flexibility for year round camping. Replacement is pretty simple and the hardest part is getting the new unit up on the roof.
A/C has two purposes. First is to condition the air which is pulling the humidity and second to cool it. If you over air condition and get the temperature down faster than the humidity you'll end up with a coach that feels like a cave. Cold and damp.

Although it will make a difference, an additional 2500 BTU is not going to make much of a difference, especially in Florida if you're in full sun. Add a 2nd unit.

Putting a second unit on a 27ft mh is a tall task. His could be as he stated 12500 and swapping it for a new 15k heat pump would be money well spent. The new units are more efficient. Better cooling yes. Enough? Who knows.

Do you have a place to add a 2nd unit? I removed our vent fan and put in a 2nd unit. It wasn't pre-wired but I ran a cord along the ceiling in a cord track (found at home depot). I plug the unit into the dedicated outlet used by microwave. I just unplug the microwave when I need the additional cooling. The unit is a BriskairII HE that is designed for a 15 amp circuit.
Cools really well, and sure helps on those really hot days.

I replaced my 13500 (2002) with new 15000 units and it made a major difference. They are lower profile and w/ a new thermostat makes a much better A/C situation in our 02 Dutch star.

Dale.Traveling wrote:
Certainly, but before making the plunge check a few things.

1. Take down the lower unit (the ceiling fixture inside the coach) and with a flashlight check the fins of the interior heat exchanger. Even with the air filters a lot of debris will get past and coat the fins and degrade performance.

2. Get up on the roof and remove the cover. Clean the fins and the external unit plus check the fins. If the soft aluminum fins are bent do your best to comb them as best as possible.

3. As best you can seal the interior duct work. While doing #1 above check to ensure minimal leakage between the intake and exhaust. Use aluminum tape to seal.

I have the same thoughts as Ivylog with regards to a heat pump. A heat pump will cost more but will give you more flexibility for year round camping. Replacement is pretty simple and the hardest part is getting the new unit up on the roof.
A/C has two purposes. First is to condition the air which is pulling the humidity and second to cool it. If you over air condition and get the temperature down faster than the humidity you'll end up with a coach that feels like a cave. Cold and damp.

X2. There is nothing magic about a "new a/c unit" for cooling. A/C units use compression and expansion of gas to cool. So long as the gas has not escaped the unit, the compressor still compresses, and the blower still blows, then it's debris and build up on the unit that will cause it to cool less.

They sell a/c fin cleaner at Home Depot. It's great to use. Clean EVERYTHING up. Take off the shroud and remove any debris.

I've seen A/C units cool excellent that are 30 years old so long as they are kept clean!

Short answer: YES it will stay cooler with a larger A/C
Longer answer: Global warming is a myth, or so some folks fail to convince me,'

The point is as the world gets warmer the improvement will be overcome

Also I can;'t say HOW much.. I upped both mine from 13.5 to 1500 each and the results have been slightly positive.. Not as much as I thought. but it was improved.

1. They do not make and never have made a 12.5 k btu AC. You have either a 11.0 or a 13.5.
2. A 13.5 AC WILL NOT cool a RV 25 foot or longer to comfortable temps in 90 plus ambient
3. Going to a 15k will help a lot. That extra 1500 BTU's will be enough to get you comfortable on a 27 foot unit.
4. Since the AC is almost 25 years old, it will be better to replace it and not wait until it fails. Doug