Dometic Roof Air condensation

[GSwaim]

Hey all, I've got a problem with my livingroom Dometic 15K Penguin A/C & heat pump that I need to see if anyone has experienced. It is leaking condensation into the bus after cooling for several hours. I've inspected the drip tray under the condenser and ensured all the drain lines are clear and this part of the AC appears to not be the problem. I've traced the problem to the return coolant line back to the compressor. It came with a sparce amount of black spray on insulation to prevent temperature change but the insulation has gotten gooey and is falling off somewhat causing the line to condensate excessively into the bottom of the AC. This water of course finds it's way downhill into the coach. Since there doesn't appear to be any catch tray below the compressor or on this line, I assume Dometic counted on the insulation to prevent condesation. Has anyone out there seen this before or am I barking up the wrong tree here? If I'm on track where does one find some of this spray on black insulation Dometic originally used?

[jack14r]

Is it possible that the evaporator is freezing,while you are running the unit does the air flow decrease even though the fan speed has not changed? If this is the case then try to run the fan in the max speed and see what happens,this reduced air flow usually indicates that a little freon has leaked out and it is freezing,in order to add freon the technician must penetrate the copper tubing with a schrader valve and adjust the freon with his knowledge,there are not charts that I have seen for the roof airs.

[GSwaim]

Thanks, the air stay cold and strong no matter how long the unit runs but the condensation leaks down from the rear hold down bolt. I removed the cover and could see that my catch tray under the condenser was draining fine but the low pressure line to the compressor has no drip tray and the insulation appears to be insuficient to prevent this tube from condensating. This water drips into the floor of the AC unit and finds it's way down the hold down bolts into the coach. I'm looking for experience from the group on this condition and what spray insulation can be gotten and used.

[Jon Wehrenberg]

Gary,

Seems you have several choices but really only one appropriate one. You can seal all possible entry points beneath the dripping suction line. You can fashoin a drip tray with a drain to collect the dripping condensate. You can insulate the line. I vote for the last option. I would guess if you shut down the AC unit and let the dripping line dry out there are foam sprays that might work if you use care and mask off everything, there are insulating tape wraps, and there are foam rubber pipe insulators you could secure with nylon wire ties. There may be other choices as well.

If one of the AC units is doing this the others are likely to follow so I don't see where you have any choice but to resolve it on the unit in question and then apply the same solution to the others.

[johnklopp]

Gary,

I would go with Jon’s suggestion. Insulate the suction line from the evaporator outlet to the compressor inlet. The suction line is dripping because its surface below the DEW point. In order to stop the dripping you need to insulate the line AND provide a vapor barrier to prevent moisture from reaching the suction line.

Do not use a spray on insulation. Spray on insulation is typically used in high volume production and seldom used for repairs. Spray on insulation also has a marginal vapor barrier.

You will find a variety of roll insulation products at any refrigeration supply house. Do not use fiberglass insulation. Use a closed cell foam insulation tape such as Virginia KEMP part number 4E390. Sells for about $17 at WW Grangers. The tape is approximately 2 inches wide and 1/8 inch thick with an adhesive back. Wrap multiple layers and your problem will be gone.

[BoaterAl]

NAPA also has the black A/C tape available in there NAPA TEMP line ...part number 209491. Measures 2 1/4 wide X 1/16 thick. The item is rolled up in a box and probably more then you will need. I have found lots of uses for this sticky product where insulation or water protection are needed.

[dmatz]

Gary

Find a Johnstones supply or a refrigeration supply in your area. Get some armaflex pipe insulation and a roll of armaflex tape, and armaflex glue, so when you slice the pipe insulation you can seal it back up. Any air that can get tot the piping will allow condensation to form. I am not familiar with the Napa product however the armaflex product is professional grade refrigerant pipe insulation.

[gmcbuffalo]

Good info guys. two thumbs up.

[GSwaim]

Thanks all, I'm starting to think my problem is just not a condensation issue. Yesterday I was watching to see where the unit was doing the condesating and saw the return line ice up. Of course when the unit shut off all that ice turned to water. I Hadn't seen it do this before now so didn't realize that was a symptom I had. I'm now starting to thing I'm getting some exhaust air mixing with the intake air. If that isn't it then I'm inclined to start thinking the unit is having a unrepairable problem and change the whole unit out. I did some checking on my unit's part number (630515.321) but Dometic is saying the number has been updated to the 651515.301 which equates to a 13.5K AC/Heat pump ducted and compatatble with the 5 button comfort control thermistat which I have Anyone know of a good vendor that will sell these at a good price?