A/C Leak

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Texan245

Texan245

Member
Joined
Jun 15, 2019
Posts
12
Location
Just west of Texarkana, on the Texas side!
Okay, I?m a newbie to the full size bumper pull world.  Recently I bought a new (to me) 2016 FR Salem Hemisphere 30?er.  It has two roof top A/C?s, one vented in the living area and one non vented in the bedroom.  I?ve only had it out twice, once in direct sunlight and once in a shaded site.  The vented A/C in the living area runs fine all day long but at night it?ll start leaking after (I?m assuming) that the ice breaks off the coils.  I can hear what sounds like critters scampering on the roof, then the steady drip begins.  The non vented unit in the bedroom doesn?t do this at all.

Where do I start to debug this shy of taking it in for service?
 
Pull the outside shroud off and see what is blocking the water flow.
 
Welcome!!!

The pan under each unit should have drain holes which may have become blocked on the leaking one, and that may be the cause of the leak..... And while you are up there, clean the coils on both very carefully. Try not to bend the fins.
 
Texan245 said:
  I can hear what sounds like critters scampering on the roof, then the steady drip begins.  The non vented unit in the bedroom doesn?t do this at all.
Click to expand...

Love this description  ;)

Agree with the others, drip pan is not draining. Some (non-RV) window ACs purposefully drip such that the fan picks up the moisture and blows it through the coils to increase cooling efficiency - you can hear the water ticking across the fan blades (critters  ;) ). RV ACs are not meant to do this.
 
There are a few causes of Drip Drip Drip

Icing of the evap coils is one.. Exactly as you surmrise. there are a few causes for this I will disuss later..

One of the causes (I am told but have been unable to prove) is dirty intake filters inside the RV.  THis can also cause a 2nd issue... As the filters clog the blower creates a vacuum in the space above the filters. As water condenses on the hopefully about 35 degree evap it drips into a tray. the  vacuum can suck the water out of the tray and up into the space in front of the Evap coils... Then when the thing shuts down and the blower stops sucking.. NIAGRA FALLS (At least that is how it happens to me)

Clogged filters can redue air flow so the evap drops cold enough to ice up and.. Well you think that is happening.
Low fan speed.. Likewise use HIGH only
Low Refrigerant charge (I've seen this several times)
Some (not all) Roof A/C's have a frost sensor. A metal rod with cable or tube that sticks into the eap usually near the bottom right.. Sometimes the installer leaves it lying in the drip tray. Don't work when it's in the drip tray.

And last clogged ductwork.

 
Duh.....I?m really not as ignorant as I sound.  I should?ve thought of that myself.  Thanks for jogging my memory.  I have had two new hips installed over the last 18 months so this sounds like a good Fathers Day chore for my 21 year old welder son. 8) 8) ;D  ;D

Thanks folks!!!!
 
You said vented... does that mean that the cold air blows out through ducts rather than direct from the unit? No RV a/c unit is "vented" to the outside, i.e. there is n exchange of inside and  outside air.

Is the drip inside? If so, the advice above about the pan and other rooftop items are probably not helpful.  Everything above the roof line is supposed to be isolated and no water on top or or above the roof should be able to get inside (unless the rooftop gasket is defective).

Water dripping inside is caused by condensation on the heat exchange coils or within the ducts. In extreme cases ice can form.  The most common cause is mixing of the chilled ir with the warmer intake air at the ceiling unit. This can happen with ducted as well as unducted models because the plenum for the chilled air is immediately adjacent to the warm air intake. Inadequate seals between the tow let cold air get recycled instead of flowing out, and the cold intake freezes the warm moist air on the fins.  Low intake air flow can also cause this, so check for a dirty intake filter or possible blockages. Sometimes the factory guys run bundles of wires right thru the intake area.

On the output side, the ducts near the a/c unit get very cold and if warm moist air surrounds them, it condenses and builds up on the ducts, eventually dripping out.
 
Gary RV_Wizard said:
You said vented... does that mean that the cold air blows out through ducts rather than direct from the unit? No RV a/c unit is "vented" to the outside, i.e. there is n exchange of inside and  outside air.

Is the drip inside? If so, the advice above about the pan and other rooftop items are probably not helpful.  Everything above the roof line is supposed to be isolated and no water on top or or above the roof should be able to get inside (unless the rooftop gasket is defective).

Water dripping inside is caused by condensation on the heat exchange coils or within the ducts. In extreme cases ice can form.  The most common cause is mixing of the chilled ir with the warmer intake air at the ceiling unit. This can happen with ducted as well as unducted models because the plenum for the chilled air is immediately adjacent to the warm air intake. Inadequate seals between the tow let cold air get recycled instead of flowing out, and the cold intake freezes the warm moist air on the fins.  Low intake air flow can also cause this, so check for a dirty intake filter or possible blockages. Sometimes the factory guys run bundles of wires right thru the intake area.

On the output side, the ducts near the a/c unit get very cold and if warm moist air surrounds them, it condenses and builds up on the ducts, eventually dripping out.
Click to expand...

No, it isn't like a window unit.  When I say vented, it has duct work in the main cabin, the bathroom and in the bedroom that flow from the main unit.  Or I can open the vent inside on the main unit and most of the cool air will flow out it.  The dropping water is coming from the vent on the main unit inside.  I've already got it on my 'to-do' list to get a new filter to see if that takes care of the problem.  When in there, I'll look for blockages as well.  No condensation forms around the ducted vents placed in other areas of the camper.  When I shut off the main output vent on the unit, obviously cool air passes through to the ducted vents better.  Closed or not, at night, that's when the Niagra Falls effect takes place.
 
Gary RV_Wizard said:
(unless the rooftop gasket is defective).
Click to expand...

Gary barely touched on this issue. If the gasket, which seals the AC to the roof, has relaxed, it could be allowing water to go from the roof, by the gasket and into the RV. I'd recommend removing the interior face place, and check the torque on all 4 studs/nuts which tightens the seal on the roof. Just turn each nut maybe 1/2 of a turn. Don't over do it.  If you don't have a leaking problem when it's raining, then this may not be your issue. I would still snug them up a little.
 
Rene T said:
Gary barely touched on this issue. If the gasket, which seals the AC to the roof, has relaxed, it could be allowing water to go from the roof, by the gasket and into the RV. I'd recommend removing the interior pace place, and check the torque on all 4 studs/nuts which tightens the seal on the roof. Just turn each nut maybe 1/2 of a turn. Don't over do it.  If you don't have a leaking problem when it's raining, then this may not be your issue. I would still snug them up a little.
Click to expand...

To the point on leaking while raining, last weekend we got about 2" of rainfall one night we were camped.  I saw zero leaks anywhere as a result of the rain.  However, I'll snug up the gasket seal nuts just to be safe.  Thanks for the pointer.
 
Given what Texan245 describes, chances of a roof gasket leak seem very slim. For one thing, that sort of leakage would be higher during the day than at night.
Do not torque the corner bolts real tight - they should just be snug.
 
YOu called it "Niagra falls effect" a term I used in an earlier post

When I said Niagra falls I did not mean "Drip Drip Drip"

I meant SPLOOSH like a gallon or two of water cascading down all at once (You know like the Falls.)

If that happens when teh blower shuts down (Drip drip while it's running) 100% dirty filters no other cause.
 
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