Helpful Gadgets: An Air Flow Meter

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When something seems wrong with the cooling or heating system of a RV, it is difficult to go to the mechanic and simply say something generic like, “my RV is not cooling like it used to.”

A helpful gadget that every RV owner should keep in their unit is an air flow meter. The best one to keep in a RV is one that shows both the air flow coming out of the air conditioner/furnace and tells the temperature. When the air conditioner feels like it is not cooling right, the air flow meter can check the air flow and temperature to help provide specifics like the air not being cool enough or a decrease in air flow. To test, turn on the unit and hold the meter up to the vent of the air conditioner to check air flow. Then switch to temperature and do the same thing.

If you are starting to see a decrease in air flow, chances are it is the cold air return filter. Low air flow coming out of an air conditioning unit may be a sign it is time to change out or clean the filters. To change the filter on a standard AC unit, unscrew the cover from the ceiling of the inside of the unit. You will see two filters inside the cover. Replace or clean these filters, put the unit back together and retest the air flow. You should notice it goes back to running with normal air flow. For ducted roof air units, the filter is generally located behind the cold air return vent.

If the temperature is not what is used to be, it may be time to take the RV to the dealership and have the air conditioner recharged.

It is a good idea to keep an air flow meter handy so you can test the air flow and temperature of your RV’s air conditioning unit and furnace during normal operation. It will allow you to provide a mechanic with more specifics if something is not working properly.

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12 Responses to “Helpful Gadgets: An Air Flow Meter”
  1. Jim Phillips

    I don”t use Adobe Flash Player because of the numerous articles about its lack of security. Is there another program I can use?

  2. Gary

    Where do you get a meter like the video is showing? One that shows air flow and temp? I might add at a reasonable cost…

  3. David

    When testing temp and air flow always try to test using the same conditions (same vents open, same speed setting and same set point temperature).

  4. Richard

    You never actually said I what the temperature should be. The 67 degrees you registered on you meter seems warm. I just had my ac serviced on my truck and the reading was 32 degrees at outside temperature of 84 degrees. How much of a temperature drop should we expect from the outside temperature?

    • Customer Service

      Hi, Richard. Thanks for bringing up the temperature reference. RV roof air
      conditioners will only be able to cool the rig about 20 degrees lower than
      outside ambient temperature. That’s why it’s important during hot
      times to try to park the rig in a position where you can get some shade or
      cooler temperatures on the roof area. Newer, more efficient units
      can go down to about 25 degrees cooler but that is why you see some of the
      bigger rigs with 3 units! With that said, you should see
      temperatures coming out of the air conditioner unit at about 30 degrees
      less than outside temps, but I would use the temperature of the living
      part of the coach to check efficiency.

  5. mike

    what should the temp be in relation to outside temp? that would have been a guide line.

    • Customer Service

      Hello Mike,

      A roof AC unit can only cool down inside air by 20 degrees. So if you let the unit sit outside in the beating sun at 100 degrees outside temperatures, the inside can get well above 120 degrees and the roof AC can only cool down to 100! That is why owners need to pull down all the shades, park in a shaded area, use the awning to provide shade, and even install some window insulation products or dual pane windows. We do have an article on the site about making your roof AC run more efficient. The roof AC pulls interior air into the air return vents and extracts heat from it and pumps it back into the rig. So the cooler you can make it inside to start with is critical for the roof AC to run more efficient.

      Hope this helps,

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