Forum Discussion

SpoiledRotten's avatar
Mar 05, 2015

Who has replaced your A/C unit?

I've got an A/C unit that needs to be replaced. The ones with the rooftop and the inside unit attached to the bottom seem simple enough, but mine has the supply and return air ducted from away from the unit.

I don't see any Youtube videos regarding this type of replacement. Have you replaced yours and what's is involved? BTW, mine is 15K unit, but that shouldn't be any issue.

Is this considered an "air box" installation?

8 Replies

  • wa8yxm wrote:
    Might be easier than you think.. First odds are you do not need to replace ALL of it,

    your A/C is designed in 3 parts From the top down:

    The rooftop unit, this is the guts of the A/C, contains all motors, coils, blowers, fans and such

    The Middle unit: This interfaces with the duct work

    The lower unit: This contains the controls, air filter and such

    In my case the upper unit failed... NOW, My units were Carrier Air V, Carrier no longer makes RV Air conditioning and frankly I do not blame them, there was a construction flaw that would have taken out my other unit as well had I not fixed it.

    BUT two diferent companies make "Drop on" roof top replacements that fit the Carrier middle unit and work with the carrier lower unit.. I had to change one socket is all on the control box. The cost of the adapt-a-kit to swap em out was less than the labor to replace the middle unit.

    With all other A/C units they will fall into one of three groups:

    1: Still in business, so you can order up a new roof top unit
    2: No longer in business but someone else makes a drop on replacement
    3: Still in business but others make drop on roof units as well.

    NOTE, you may also be able to "Upgrade" (I went from 13,500 to 15,000 BTU).
    It would certainly be nice if you listed the two companies making "drop on" units to replace the Carrier.
  • If you add the heat pump option, you need to consider the additional thermostat requirement. Depending on your install, it may require a new thermostat or just a thermostat reset. Tell us what you have are we can tell you what you may need.
  • Good info, guys! I already have the 15K BTU, so I won't be upgrading the size, but the heat pump option sounds great. I just didn't know about the duct part. If the new just fits down on the old system, I'm good. I don't have the bottom part, since my ceiling inside is finished, with the duct work, supply and return, running to both ends of the 5er.

    Thanks again, and if there is anything else you think I should know, please post up.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Might be easier than you think.. First odds are you do not need to replace ALL of it,

    your A/C is designed in 3 parts From the top down:

    The rooftop unit, this is the guts of the A/C, contains all motors, coils, blowers, fans and such

    The Middle unit: This interfaces with the duct work

    The lower unit: This contains the controls, air filter and such

    In my case the upper unit failed... NOW, My units were Carrier Air V, Carrier no longer makes RV Air conditioning and frankly I do not blame them, there was a construction flaw that would have taken out my other unit as well had I not fixed it.

    BUT two diferent companies make "Drop on" roof top replacements that fit the Carrier middle unit and work with the carrier lower unit.. I had to change one socket is all on the control box. The cost of the adapt-a-kit to swap em out was less than the labor to replace the middle unit.

    With all other A/C units they will fall into one of three groups:

    1: Still in business, so you can order up a new roof top unit
    2: No longer in business but someone else makes a drop on replacement
    3: Still in business but others make drop on roof units as well.

    NOTE, you may also be able to "Upgrade" (I went from 13,500 to 15,000 BTU).
  • There are UTube videos all over the place on RV a/c. Put in "Dometic RV air conditioning" in UTube.

    The a/c unit and the inside ceiling vent cover are ordered separately. Many of the 15K units are heat pumps.

    They don't appear very difficult to install.
  • The hardest part of the job will be getting the new unit up on the roof... Disgarding the old is always easy and fun !!
  • usually 4-6 squarehead screw hold the inside trim panel, remove that and there should be 4 bolts inside there. The bolts are extra long and are all that hold in most units. Then you disconnect the white harness plug to the upper a/c assembly and it's ready to remove from the roof. This is for dometic units but coleman is prob similar. Doesn't matter if it's ducted. The ductwork isn't connected to the unit itself, it simply blows air through via the fan when it is running.