Dual Whisper Dometic A/c on Bighorn

[redmancb]

While checking out a freeze up in my Bedroom unit,
I found a strange situation in my duct work..
I uploaded a crude drawing. I have cold air going past the vent ,traveling 1,2,3 and coming back in the ductwork at the warm return vent...

If I block the (front camper cap) end of the duct at point 1 with a rolled up shirt, , the cold air stops at point 3..

Does anyone else have a open ended duct like this, or am I missing stops at point 1 and 3 ?

 

[TravelTiger]

I don't know if you're supposed to have it, but I blocked ours off. To me that's wasted cold air going past the last duct in the room.


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[redmancb]

The volume of air coming out of the last duct is far better with the duct blocked.
My concern was the reasoning behind having cold air channeled back into the input duct.

Seems silly in light of the freeze up I had and the water leaking out of that same input duct.

I called heartland, and they would not commit to a straight answer.
I must take it to a dealer.

The 2 dealers within 2 hours of my home, are extremely useless when it comes to service after the sale.
They are simply going to call heartland for the same answer heartland wouldn't provide me .

 

[TravelTiger]

The volume of air coming out of the last duct is far better with the duct blocked.
My concern was the reasoning behind having cold air channeled back into the input duct.

Seems silly in light of the freeze up I had and the water leaking out of that same input duct.

I called heartland, and they would not commit to a straight answer.
I must take it to a dealer.

The 2 dealers within 2 hours of my home, are extremely useless when it comes to service after the sale.
They are simply going to call heartland for the same answer heartland wouldn't provide me .

Maybe call HL and see if a mobile tech can be authorized to come to you? You may have to pay the mobile fee, but worth it to save on driving back and forth to a dealer you don't trust.


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[NHCelt]

What you have is the reason for the freezeup. You should have 4 foam blocks in the system... One at each end if the front to back duct runs just past the last intake or exhaust. Two front, and 2 back. They have been found everywhere within the ducts. Find them and put them in their places. Seal them with silver metallic hvac tape. I had the same issue. Problem solved ow that there is no more air mixing.

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[NHCelt]

It seems that this us a constant manufacturing issue and a source of freeze-ups and resulting leaks. Use a flashlight and cell phone camera to see into your ductwork.

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[redmancb]

on the back, I found 1 block in place and the other just setting off to the side. On the front, above the bed, I have 2 long tunnels of duct that disappear into oblivion above the closest. They met somewhere, since when I block the cold past the vent, at stops coming in the intake vent from the closest side of the duct work.. seems senseless to have all that extra duct up there, and then block it off.. it just trouble looking for a place to happen.
....I don't understand why Art at heartland couldn't confirm, or at least consult with someone to confirm my suspicions.

 

[Relayman]

I was having the same issue with the condensation leaking into the bedroom through the ceiling panels ( which by the way... is the bottom of the ductwork). the dealer did the TSB to alleviate that but I noticed there were foam blocks in the cold air supply side duct work just aft of the bathroom register...and another one just aft of the bathroom vent fan and shower skylight. this effectively separates the living area and bed/ bath area cold air supply. there are no blocks in the return air ducting (except at the ends).
I was thinking that both units shared common ducting so both worked together ? the way it is now..whichever unit is running...it will pull warm supply air from the entire coach..but only supply cold air to its own space. is this correct ?
2017 Bighorn 3270TS.

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[Gary521]

Yes, that is the way your unit is made. I have this model and others, on the forum, with the same model, have confirmed this.

 

[Relayman]

Yes, that is the way your unit is made. I have this model and others, on the forum, with the same model, have confirmed this.

There does not seem to be much air volume coming out of the rear AC registers . the supply temp is 58.5 degrees. it's just not flowing very much into the living / kitchen areas in my 2017 Bighorn fifth wheel. any suggestions *?



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[NHCelt]

Use something to make directional baffles or flaps that you can stick to the top of the ductwork upstream of the vent. It may take some experimenting, but it sure will work. I used some sticky foil backed rubber hvac insulation from frost king.

 

[Relayman]

I thought about doing that. just haven't figured out what to use yet. thanks Celt!

 

[SNOKING]

I turned the registers on the supply side to have the fins in line with the air flow instead of across it, to see with that makes a difference, however have not used it enough to tell. Just seems that having them across the air flow has the first half the air hits trying to defect it up and over the second half.

Worth a try!

Air > fins = This would try to send air left and right in the trailer.
Instead for Air > fins |||| This would try to send air front and back in the trailer.

Chris

 

[Nabo]

We are sitting in central AL with heat index at 103 degrees today at 1:00 pm central time. The supply ducts are putting out 60.1 degrees with the inside living room digital thermometer showing a comfortable 75 degrees. We have the supply vents turned at a little over a 45 degree angle. In the afternoon with the western sun hitting the back window, the inside temp usually gets around 78 degrees but quickly cools back down after dark. We did get a dehumidifier to help pull the humid air out of the camper and right now we are emptying it daily. Got to love summertime

 

[nander]

We had our AC fixed for the technical service bulletin. Now the main AC cannot keep up with the heat in the trailer. The ducts don't seem to be putting out much air. I know this has been discussed before and we will try some of the suggestions, but in the meantime....it's hot. The outside temp is about 101. We are sitting in direct sun. The inside temp is about 90. Not cool at all.

I don't know what Heartland and Dometic can do to remedy this problem, but something needs to be done. Of course, we can just go north every summer!

 

[TravelTiger]

Sorry Nancy! I feel your pain. The Texas heat is brutal, and anything over 98 outside can make it uncomfortable (80+) inside, even with our mods.

The most effective for us was add the cutoffs just past the last ducts in the area -- separating the two AC ductwork.


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[nander]

Sorry Nancy! I feel your pain. The Texas heat is brutal, and anything over 98 outside can make it uncomfortable (80+) inside, even with our mods.

The most effective for us was add the cutoffs just past the last ducts in the area -- separating the two AC ductwork.


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Thanks, Erika! We'll have to try that!

 

[jmgratz]

Here are three things that helps ours alot. #1 - Use a swim noodle and you can block off the supply duct between the bathroom and livingroom. #2 - Use a swim noodle and block off the duct just past the last duct nearest to the rear cap and front cap. You see the duct extends into the rear and front cap where there is no vent and that air is just wasted. #3 - Turn off the Air Conditioner at the circuit breaker. On the roof remove the AC cover (just screws on). Inside you will see a metal cover that covers the evaporator coil. It is held on by several bolts/screws. Mine was missing several of them and the metal cover was not sealed. Remove that metal cover to expose the evaporator coil. Look at the coil to see it there is any dirt/debris in it. Use a soft brush or even a large paintbrush and carefully brush the dirt/debris off the coil. Replace the metal cover over the Evaporator Coil. Replace the screws and seal the metal cover with foil AC tape. If the coil was dirty of stopped up at all you will get more airflow and a colder air. Replace the cover for the AC unit and exit the roof.
Turn on the breaker for the AC and reset the thermostat. Then check operation.

All of this made a huge difference in the operation of ours. Good Luck

 

[Relayman]

Well..what I did was get some foam blocks...shaped them so they fit the register rings...formed them into "ram air" shaped concave scoops..and placed then just last the last supply registers fore and aft to help "divert the air down through the registers at the ends. Next...i made a plastic "scoop" that covers about half of the supply duct in the middle register to "grab" some of the air flowing to the end and divert it out into the coach. Made a HUGE difference.

 

[wonder63]

Well here it goes we have a 3270rs 2015 big horn. Had the same problem with no air coming out of ceiling vents. Checked ductwork with light and camera omg who designs this mess. Holes in ductwork recycling air directly back to warm side.
1. Used silver tape and sealed holes
2. Who designed a common ducting system for two ac units needs to go back for some more hvac training. I worked on hvac system this doesn't work. It will work against itself.
3. Took round pipe insulation and blocked the bathroom duct just past the vent towards back of camper.
4. Used same material and block the duct past the last vent hitch end of camper. Duct was open to the front cap amazing.
5. In kitchen end duct above cubbard used same and blocked duct.
6. At cold vent just past the ac unit used camera. Found open area going to return duct sealed with tape.
7. While doing that noticed at the ceiling fan there was no duct at all. Cold air going up into roof what a mess.
8. While at ceiling fan decided to remove fan and cover because a area around fan was very warm to the touch.
9. No insulation actually could touch the underside of roof decking which was say the least very warm. Used Styrofoam to insulate got about 2 inches and also insulated the aluminum ceiling beams.
10. Shame on heartland should have bought a Montana


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