Roof mounted 15k air conditioning

[RDalr]

Hi,
My 15k roof mounted AC unit isn't providing sufficient cold air to cool the fiver temperature down. My question is: can we add coolant to these roof mounted AC units? or, are all those units sealed which would preclude adding coolant?

Thanks

Richard

[RDalr]

Opnspaces...thanks for the info. I am familiar with the 15 to 20 degree difference between the temp in the fiver and the output of air at the ac. When I said that my temp was 65 degrees at the ac output, I would say that it must have been 80 deg in the coach.
That said, I received very good advice about cleaning the coils. Having watched 6 videos on YouTube, I will start there in a few days. More to follow.

[opnspaces]

RDalr wrote:
Thank you all for your comments.
My unit is 50 amps. I should have bought a second ac when I first bought it. The compressor kicks in but when I check the cool air temp, I get a reading of 64 degrees. If it was working correctly, I should see a cool air reading of 42 or 43 degrees.
Is there a thermostat or thermometer inside the ac which commands cooler air? If so, is its placement inside the ac critical to achieving that goal?

Unfortunately the way AC works you should only see a 14 to 20 degree difference between the temperature of the input and output air. So to get 42 degrees out of the vents it would be 62 degrees in the coach.

If you have a ducted unit you should look for air leaks on the output. On my trailer I pulled the intake grill off the ceiling and I could see many places where the cold air was either mixing with the warm air, or sneaking around the ducting and into the attic space. If you find the same in your system you can fix it with some foil ducting tape from Home Depot or other home improvement stores.

Please note this is not the standard dollar a roll cloth duct tape and we all use around the house. This is a metallic tape with a peel off butyl backing that they will sell in the aisle with the HVAC ducting.

Tape

On my trailer it took me about 20 minutes with a scissors to reseal the airbox in my AC and now the vents blow much more efficiently. Of course the irony of all this is I never use the AC. As in it's probably only been turned on a total of 5 times in the 13 years I've owned the trailer.

[MFL]

As suggested above, sounds like it needs cleaning, with vent temp at 64, unless it freezing up.

Jerry

[RDalr]

Thank you all for your comments.
My unit is 50 amps. I should have bought a second ac when I first bought it. The compressor kicks in but when I check the cool air temp, I get a reading of 64 degrees. If it was working correctly, I should see a cool air reading of 42 or 43 degrees.
Is there a thermostat or thermometer inside the ac which commands cooler air? If so, is its placement inside the ac critical to achieving that goal?

[Dave_H_M]

Chris hit the mark on what was ailing mine. A lot of the air was cooling eh space between the ceiling and the roof. :R

I was surprised that no one suggested the ole air temp in and air temp out to see if it is producing from the get go.

[wa8yxm]

Before you throw money around. INSPECT AND CLEAN

Go, as the song is titled UP ON THE ROOF. Take a phillips head screwdriver. A pair of pliers (slip joint are fine) a pocket knife and a magnetic parts tray (if you have one) to toss screws in.

Remove screws holding the cover on

Coleman these are 4 screws top center
Most others 10-14 more or less around the bottom edge.

Lift odd top.

Coleman look at the CONDENSER coils (the outside coils) are they clooged with CRUD? using brush brush it off, or peal it off.. then Jump to OPTIONAL: below

Others. Remove cover over condenser/fan assembly this may involving some combination of: cutting foil tape, bending tabs or removing more scews. On my Advent air I only cut open the condenser then I bent the dual cover back on itself.

This time you inspect the FAN side of the condenser. is it clogged with crud?
Using the brush brush it loose.. Compressed air may also be helpful but be careful because you can bend the FINS and that is not good. Get the crud out.. YOU MAY need to move or reposition the fan. a spring clip can be pinched a bit by the pliers and moved to the "Non-Split" part of the fan shaft then it will slide farther on, or off. the motor shaft.. With my ham size hands I have to do this. not all will.


OPTIONAL: Clean with "Coil Cleaner" as per label direcrtions

Reassemble. if you had to cut tape Gorilla tape is a good replacement. Duct tape likely is not or you can get metal tape at Auto parts r us.

Do this at least 2x a year or as needed.

[parkmanaa]

On some makes/models of 5ers the mfg. has made provisions for adding a 2nd unit.
If they did on your's, it would be quite easy to accomplish. They cut a hole the standard 14" x 14" you need, it's just covered by veneer inside and rooftop. Also, the wiring is usually in place for it at that 14" opening.

Agree with other's, techs don't like to service the rooftop air, but some will although I seriously doubt trying to add freon will help. If cleaning coils does not work you will probably want to pursue that 2nd A/C rooftop unit. A 13,500 btu would probably be sufficient for the 2nd unit.

[Chris_Bryant]

Clean it, check the ducting- often half the air is lost to badly sealed duct work.

[Big_Katuna]

Your evaporator may need cleaned. The filters on roof ACs are terrible.

You have to go the roof, remove the cover and remove front sheet metal to get to it.

There are Youtube videos.

I agree you might need another unit.

[2edgesword]

Adding refrigerant would not be the answer unless the unit wasn't sufficiently charged in the first place. Possible but not likely. That said if somehow it wasn't properly charged at the factory or developed a leak there is a way to tap into a closed unit to add refrigerant. Unless you have the equipment to measure low and high side pressure and a leak detector you should leave that to an A/C tech.

If it's not an issue of the A/C putting out less than it's suppose to adding another A/C (cost) is going to depend on whether you already have 50 amp service. If you have 50 amp service adding a second A/C would require minimal new wiring and you shouldn't need a new converter. If you currently only have 30 amp service then it becomes a more involved and more expensive project (wiring, new converter in addition to the new A/C unit).

[garyemunson]

The problem I see reading your post is "unit", singular. Unless your 5er is a baby model, you probably need 2 to be comfortable in hot weather.

[SoundGuy]

RV roof mounted A/Cs are sealed and not intended to be recharged.