Roof Top A/c

Discussion in 'General RVing' started by parkercouple, Jul 23, 2007.

  1. parkercouple

    parkercouple New Member

    I have a 97 Fleetwood 29 ft Class C. My Question is are the New A/C units better then what i have. Mine doesnt keep the inside of my R/V very Cold. It works and Blows Cold but it seems like I would get way more Air out of the Ducts.

    Thanks
    Chris :)
     
  2. ARCHER

    ARCHER Senior Member

    Re: Roof Top A/c

    Guess you keep the filters cleaned. and the fins cleaned on the unit itself, and follow all the instructions in the OM. Being ten years old, it may just be worn out and may have something else wrong with it. Just a couple thougts.
     
  3. DL Rupper

    DL Rupper Senior Member

    Re: Roof Top A/c

    RV air conditioners are closed units and can't be recharged unless you can find a refrigeration specialist that can tap into it.
    If it's blowing cold air, your best bet would be to insulate your windows with reflective insulation and your air vents with foam padded pillows during the heat of the day. Most single air conditioners are not up to the task of really getting the air cold in larger RVs. If you can get the temperature down 10 degrees on a really hot day (90+)you are lucky.
     
  4. Kali_Mist

    Kali_Mist New Member

    RE: Roof Top A/c

    What are the BTU Ratings? 30ft I would go with a High Efficiency AC 15kbtu you can probably get by with a 13.5btu
    If you feel yours needs recharged check your amp draw that will tell you. using a clamp on amp meter or any amp meter, check the amp draw at the breaker when on high cool, a 13.5kbtu unit runs around 12amps high cool 85+deg.
    so low amp dram in the (1-4)range on high cool means low coolant, high amp draw above 15 (your breaker would most likely trip) mean bad compressor.
    If you have a 20deg difference in out put air & outside air, then the AC is fine.
    They sure don't build them like they used too, and Carrier has gotten into the AC line they are much better built units than any available but they run on a high amp Draw 15amps.
    What i see more than anything is a return air issue, thats where your getting a leak in cold air, lower the upper controlls and make sure that all the area around the ac is taped off so no hot roof air is sneaking in, very common problem, also try retitening the roof air support bolts, if loose hot air sneaks in thru the seal.
    :shy:
     
  5. s.harrington

    s.harrington Senior Member

    Re: Roof Top A/c

    The newer AC units have 134a refrigerant which has less cooling capacity than the older R22 which you should have in your unit. 134a takes a lot longer to cool than the older stuff and doesn't get as cold so if it works don't change your unit. You may need to check that the discharge side of the AC unit is sealed properly from the intake side. Make sure the foam seal is in good condition and that it makes contact with the metal plate.
     
  6. Kirk

    Kirk Senior Member

    Re: Roof Top A/c

    First of all, did you close the shutters on the outlet from the air conditioner that are on the lower panel next to the air intake? If that is open then all air will exit there and none will be forced out through the ductwork.

    To check the unit to see if it is working correctly, get an accurate thermometer and place it next to the air intake side long enough to see what the air temperature is when entering the cooling coils. Once you know that, place the thermometer in the air exiting with the dump shutter open and see what the air temperature is when it exits the unit. The difference should be at least -18 degrees difference. If it is that or more your unit is working as it was designed to.

    What you don't tell us also plays a major part in this. First, what is the outside temperatures when you have this problem? As outside temperatures approach 100 degrees, very few RVs can be kept to temperatures where we normally set our thermostats. Yet another factor is the insulation quality of the RV and does it have dual pane glass in the windows? What make of RV is it? Are you parked in the sun, or shade? All of these factors play a major role in how well the air conditioner can do it's job.

    RV air conditioners are not really designed to use the ductwork but they just block the opening and thus force most of the air down the ducts. To do that, air movement must make a 90 degree turn, which causes a loss in air movement. They are most efficient if the air dump is kept open and an electric fan is used to move air around the RV.
     
  7. luukoutbelow

    luukoutbelow New Member

    Re: Roof Top A/c

    Just a quick tip that I used:

    Went to home depot and bought a can of henry's uv blocking paint to paint over the roof. It blocks 80% of uv rays and reflects heat. My ac kept my '26 with aluminum roof very cool with minimum effort ever during high 90's wx.
    BTW, henry's makes 2 kinds. 1 is silver and 1 is white. The white one is better but has no sealing properties. The silver isnt as good but it has some sealing qualities.

    Hunter
     
  8. DL Rupper

    DL Rupper Senior Member

    Re: Roof Top A/c

    Did you use the uv blocking paint on a metal roof? It doesn't sound like something that you would spray on a rubber roof.
     
  9. luukoutbelow

    luukoutbelow New Member

    Re: Roof Top A/c

    yeah, my roof is aluminum, however, my neighbor is a roofer and I will ask him tomorrow if he has ever heard of a paint that would work for rubber roofs. We have another RV here with a rubber roof and Im tempted to just get up there and do it anyway. Ill let you know.
     
  10. DL Rupper

    DL Rupper Senior Member

    Re: Roof Top A/c

    I missed the ALUMINUM on your first post. Sorry. The RV stores carry a rubber roof paint on primer and sealer. It's expensive but should work fairly well on a rubber roof. I do know that you aren't suppose to use any product on a rubber roof that has petroleum distillates in it. Don't know if what you are using has them in it or not. :question:
     

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