I'm starting to feel that the flow out of the main a/c is not as much as it should be. It's possible that the radiator coils on the roof are partially blocked with 'stuff'. After all, my Voltage 3950 is 14 years old and the fins have never been cleaned.How do you do it? Is it both the hot side and cold side or just one. I suppose I could get up there with a vacuum and compressed air but one youtube video said only use weak air for fear of damaging the fins.How did you do it?

I used a garden hose with low pressure and washed it from the inside out. yes compressed air will bend fins fast if your not carful.

Thanks. I hadn't thought of that. How did you stop water from going inside? I don't have access to the main a/c from the inside because it's covered by a decorative (I don't know what to call it)

Water should not get inside unless you have a roof leak of some kind. Are you getting reduced airflow inside or is the airflow good but just not as cold? If reduced airflow inside you probably have a filter that's plugged up behind that decorative panel.

It most certainly will get wet. The evaporator gets cold and water condenses on the evaporator. As dusty air goes over the evaporator, some dust particles will get caught in the moisture and eventually enough will build up to block flow and insulate reducing cooling.

Yes, if you are doing it, do both condenser and evaporator.Condensor is fairly straight forward, take the cover off and with a hose and brush (carefully) you can clean the fins. Evaporator, is a bit more messy as a hose will result in water all over the interior. They do make aircon cleaner which foams up and dislodges the crud again with a light brushing. It can be stuck on pretty good, so a vacuum won't do very good.

How to clean rooftop a/c coils? | Good Sam Community

14 Replies

Canadian_Canoer
Explorer
Apr 12, 2025
I use foaming AC cleaner. Spray on condenser, start AC.
opnspaces
Navigator II
Apr 11, 2025
In that case you probably need to get the center panel down and use some HVAC tape to seal the edges of the distribution box up. Use the $20 roll of HVAC tape in the heater and air conditioning aisle at Home Depot. This is silver stuff with an adhesive that you need to peel the plastic off of to stick it down.
Here's one Youtube video that shows what I'm talking about.
Link
- joebedford
  Nomad II
  Apr 11, 2025
  Can you imagine the amount of work to get at the a/c behind this thing?
  - valhalla360
    Navigator
    Apr 11, 2025
    Probably easier to go in thru the top and open it up rather than go in thru the bottom. It will take a little more disassembly vs your typical air/con install where there is a panel in the ceiling.
valhalla360
Navigator
Apr 11, 2025
Yes, if you are doing it, do both condenser and evaporator.
Condensor is fairly straight forward, take the cover off and with a hose and brush (carefully) you can clean the fins.
Evaporator, is a bit more messy as a hose will result in water all over the interior. They do make aircon cleaner which foams up and dislodges the crud again with a light brushing. It can be stuck on pretty good, so a vacuum won't do very good.
opnspaces
Navigator II
Apr 11, 2025
Water should not get inside unless you have a roof leak of some kind. Are you getting reduced airflow inside or is the airflow good but just not as cold? If reduced airflow inside you probably have a filter that's plugged up behind that decorative panel.
- joebedford
  Nomad II
  Apr 11, 2025
  The filters are behind two rectangular panels in the ceiling that I DO have access to. I cleaned them yesterday. I believe the airflow is low. It's a 100% ducted system and the flow has never been spectacular.
- valhalla360
  Navigator
  Apr 11, 2025
  It most certainly will get wet. The evaporator gets cold and water condenses on the evaporator. As dusty air goes over the evaporator, some dust particles will get caught in the moisture and eventually enough will build up to block flow and insulate reducing cooling.
StirCrazy
Moderator
Apr 11, 2025
I used a garden hose with low pressure and washed it from the inside out. yes compressed air will bend fins fast if your not carful.
- joebedford
  Nomad II
  Apr 11, 2025
  Thanks. I hadn't thought of that. How did you stop water from going inside? I don't have access to the main a/c from the inside because it's covered by a decorative (I don't know what to call it)
  - StirCrazy
    Moderator
    Apr 12, 2025
    the part you do is the roof top unit. inside you should have a little access and a filter that needs to be cleaned but that is basically it. outside you take the big plastic cover off and then you should be able to hose it out. mind is sealed so you don't have to worry about anything getting inside unless I haven't been diligent on my sealant checks, its a good time to do those also .

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How to clean rooftop a/c coils?

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