Air conditioning not cooling, part deux

[travelin' texans]

Wasn't trying to suggest they did anything for airflow, just stating they are a good replacement for the foam filters. If you choose not to use them or the foam filters then by all means do it, others may want to try these.

[Jeff&Karen39MB]

We are in Florida, sitting in bright sunshine all day, Ac's were working hard to try and cool Rv and failing.
Went to Home Depot, bought a portable 14000 btu LG self contained AC, ducted through rear window on slide out, and what a difference it makes.
Turn on about 9 am every morning, and shut down about 7 pm.

[Randalf]

Hi all,

We're back in Texas after a 10 day trip to Colorado, and I'm ready to do battle with the rear a/c on my trailer. I'm ready to take radical action, like trying to modify the duct system.

I have ascertained for sure that my trailer has separate air ducts for front and rear. The front 15000 unit can only contribute to cooling the rear by aiming three of the six bedroom and bathroom ceiling registers toward the hallway and putting a fan on the bedroom dresser to push cool air down the stairs. When I do this on really hot days the bedroom thermostat reads 79, which is still comfortable because the ceiling is low and you can feel the cool air blowing directly on you. I'll leave that system alone for the time being.

If I were to remove the a/c unit from the roof, would I have enough access to the air ducts to remove the supply ducts where they pass through the return air plenum? The ducts grossly restrict the return air, and all they do is feed the two forward-most supply registers! I would like to turn those front two supply registers into return air registers, and then add at least four more ceiling supply registers-- two in the kitchen/dining area, and two or more in the living room. Would I have enough room from the rooftop to perform major duct surgery?

Believe me, Jeff&Karen, I've looked at those portable units several times! Just yesterday I saw that Home Dopey has them on sale, and I paused and thought "Hmmmmmm." However, I have a proud tradition of only resorting to the most painfully expensive and time-consuming ways possible to resolve problems, and this time is no exception. I would rather radically modify the existing system and then maybe add a third rooftop unit, or a ductless Mitsubishi residential unit.

I've seen mention in other posts that Redwoods are prepped for three a/c units, even if they only come with two. If true, does that mean I could install a third unit over the living room area, maybe one of the traditional noisy ductless units?

[johnboytoo]

imho, This is a mfg defect and should go back to be fixed...

they advertise them as 4 season and I know my 38gk was not !

for reference:
http://legal-dictionary.thefreedicti...erchantability

https://www.google.com/search?q=merc...h=768&dpr=1.13

[Jeff&Karen39MB]

Best of luck to you Randalf, hope you are successful in your quest to fix AC problems.

[Randalf]

KIMG0427.jpg

KIMG0433.jpg

[Randalf]

Oops, I posted those two pix before I figured out how to add comments!

The first photo was taken inside the return air duct, and shows how the supply duct and a bundle of wires severely restrict return air from reaching the a/c unit.

The second photo shows how the supply air duct from the a/c is "installed" into the main supply duct. Some caring craftsman just hacked a hole into the side of the main duct and shoved the supply duct an inch into the opening, taped it up & called it good. the main duct is only an 1 1/2" H by 8" W, so the supply duct obstructs an inch of it. The a/c jams the cold air into the main duct at a 90 degree angle, where the air somehow sorts itself out and starts moving fore-and-aft through the main duct. Eventually, a small wisp of air ambles it's way down the main duct and reaches the back of the trailer.

[travelin' texans]

I think it was Florida Rob that added an extra return between the wire bundle & a.c. unit to solve the return problem, but to correct the duct work,e I don't know how to accomplish that.
Calling them "craftsmen" is giving them WAY too much credit, unskilled flunkies maybe.

[rob_fla]

Yep, I added a second return on both sides of both units (so each unit now has 4 return grills)

I added the second return right next to the duct line so I could not only clear the obstructions blocking the air flow but also add some foam to hold up the bubble foil from laying on top of the duct and blocking the air flow on the top.

The A/C performance / air flow is much improved but another big plus is since I have twice as much filter area, the filters do not get dirty and restrict air flow so fast.

[texastbird]

Randalf, do you have a solution to the situation in the 2nd picture? I know at some point I will be trying to get more cooling air flow from our main A/C unit.

[830hvacman]

Ok, So I noticed my rear A/C was cycling on the compressor overload but had great sub-cooling coming back to the compressor. Voltage was around 120v and compressor amps was 11.5 to 12 amps. Outdoor was about 95 deg. and about 85 deg indoors. (supply air was running about 25 deg colder with clean filters, clean evap coil, and all the s/a vents open). Both run caps checked out good and within range. So I thought I'd check the gasket between the supply air and return air at the unit - yep this unit was blown out (1st pic) so I reinstalled it and applied some good foil tape (2nd pic). Also checked the front unit and that gasket was still in place, but applied foil tape just for good measure.
My rear a/c has run for a few days now and compressor is no longer cycling, unless wall thermostat reaches target temp.
I get to test it real good this coming weekend has we have a 4 day trip planned.. The story continues....

[spindrift]

830...are you available for house calls?

[Randalf]

Yeah, 830, what about those housecalls? Weren't you in Kerrville recently, staying at the Buckhorn? If so, you were only two miles away from making a new best (pest) friend!!

texastbird, I don't have a solution yet, because I don't know whether I have access to those ducts from the rooftop. I need to watch some youtube videos about replacing rooftop a/c units to see "what lies beneath". I sure don't see any way to correct the problem from inside that tiny duct space.

johnboytoo, I agree that this is a manufacturing defect, and I'm fixin' to call the salesman at the dealership to see about getting warranty work done on this and two other issues-- the screwy hydraulics problems I'm having with the slides, and a constant water leak in the belly. I have two issues with warranty work, though: first, I'll have to pull the trailer 56 miles to the dealership and leave it for an undetermined amount of time for them to fix it, and second, I won't see what they did, so I won't be able to fix it myself in the future. I like to be able to self-rescue when we are on the road.

[830hvacman]

Originally Posted by Randalf

Yeah, 830, what about those housecalls? Weren't you in Kerrville recently, staying at the Buckhorn? If so, you were only two miles away from making a new best (pest) friend!!

texastbird, I don't have a solution yet, because I don't know whether I have access to those ducts from the rooftop. I need to watch some youtube videos about replacing rooftop a/c units to see "what lies beneath". I sure don't see any way to correct the problem from inside that tiny duct space.

johnboytoo, I agree that this is a manufacturing defect, and I'm fixin' to call the salesman at the dealership to see about getting warranty work done on this and two other issues-- the screwy hydraulics problems I'm having with the slides, and a constant water leak in the belly. I have two issues with warranty work, though: first, I'll have to pull the trailer 56 miles to the dealership and leave it for an undetermined amount of time for them to fix it, and second, I won't see what they did, so I won't be able to fix it myself in the future. I like to be able to self-rescue when we are on the road.

Well, I will be at the San Antonio KOA this weekend - Fri to Tues. - Does that work? LOL

[Jeff&Karen39MB]

Originally Posted by rob_fla

Yep, I added a second return on both sides of both units (so each unit now has 4 return grills)

I added the second return right next to the duct line so I could not only clear the obstructions blocking the air flow but also add some foam to hold up the bubble foil from laying on top of the duct and blocking the air flow on the top.

The A/C performance / air flow is much improved but another big plus is since I have twice as much filter area, the filters do not get dirty and restrict air flow so fast.

If I'm not mistaken, you dropped your LR ceiling when you were working on unit, can you explain how that was done?

[rob_fla]

Originally Posted by Jeff&Karen39MB

If I'm not mistaken, you dropped your LR ceiling when you were working on unit, can you explain how that was done?

I did not drop the ceiling, the reason I added the 2nd return next to the duct line was to get access to the duct to make the following modifications.
I was able to remove excess foam blocking air flow, secure wiring with zip ties that was blocking air flow and put some foam blocks in to support the bubble foil that was almost laying on top of the duct blocking air flow.

[hobie16]

Checked my AC units today and they were a mirror image of the ones 830 showed in his picks. Put the foam back and then covered the inlets with foil tape. I think that there wa an increase in the volume of air from the rear unit.

[Shane Wood]

I hope that redwood has fixed this problem and removed the us less foam insert in the newer models. It has been an on going problem since day 1 up to the 2015 model year

[830hvacman]

Originally Posted by hobie16

Checked my AC units today and they were a mirror image of the ones 830 showed in his picks. Put the foam back and then covered the inlets with foil tape. I think that there wa an increase in the volume of air from the rear unit.

Awesome, I am glad it worked out. (also glad I decided to take and post the pictures).
Here's to some cooler and comfortable days ahead..

[Jeff&Karen39MB]

Originally Posted by 830hvacman

Ok, So I noticed my rear A/C was cycling on the compressor overload but had great sub-cooling coming back to the compressor. Voltage was around 120v and compressor amps was 11.5 to 12 amps. Outdoor was about 95 deg. and about 85 deg indoors. (supply air was running about 25 deg colder with clean filters, clean evap coil, and all the s/a vents open). Both run caps checked out good and within range. So I thought I'd check the gasket between the supply air and return air at the unit - yep this unit was blown out (1st pic) so I reinstalled it and applied some good foil tape (2nd pic). Also checked the front unit and that gasket was still in place, but applied foil tape just for good measure.
My rear a/c has run for a few days now and compressor is no longer cycling, unless wall thermostat reaches target temp.
I get to test it real good this coming weekend has we have a 4 day trip planned.. The story continues....

Opened both of mine, the gaskets were in tact but a little pooched in the middle, pushed them back in and metal taped them both, ordered a CFM meter from Amazon, should be here tomorrow, so far have cut one register down, and will wait on the meter to check flow to see what difference I get get.
Meter was inexpensive under $20.00 so now all I have to do is make a cup cone to sit over vent and a smaller hole to fit the fan on meter and I should get close to true air flow and air temp.
Next project is remove shoe rack and insulate the front cap I know someone has done that, so any advise on making job easier will be appreciated.
Thanks in advance.