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Old 05-10-2018, 06:03 AM   #81
Jcdwing
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I know this is an old thread but I have a 31 keystone passport and seems to need some vent assistance planning to look into it this weekend

Instead of buying new different vents for the existing holes why not just add a vent or two in the existing plenum? This would add additional flow.
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Old 05-10-2018, 07:12 AM   #82
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Quote:
Originally Posted by Jcdwing View Post
I know this is an old thread but I have a 31 keystone passport and seems to need some vent assistance planning to look into it this weekend

Instead of buying new different vents for the existing holes why not just add a vent or two in the existing plenum? This would add additional flow.
Seems like a logical solution, but be sure you have the air volume capacity from your blower motor to support additional vents. What works on a system with 4 vents may not be as effective on a system with 8 vents. If, by adding two more vents, you decrease the volume going through all the other vents, you may not gain anything in cooling and might decrease cooling in places further from the original vents. Are the existing vents "restricting" air flow or is there another reason for the cool air problem? Check things like blocked ducting, leaking return/supply air plenum, dirty condenser, leaking ductwork (end of duct run and split/leaking seams along the duct.
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Old 05-14-2018, 06:42 PM   #83
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Ours was blowing into the space above the shower with no duct work for the air to flo through. the husband bought some kind of foam to put in there and formed a tunnel to direct the air through. that worked really well.. You would think with all the money we pay for these things they would build them the correct way.. Geez
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Old 05-29-2018, 05:43 PM   #84
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Update.

My 2017 3350 keystone passport the air conditioner was sooooo loud could hardly talk. Air somewhat squealing trying to go through the “cool down straight out opening “

First step clean up and tape the exit area of the brisk air.

Second I added another 4 inch ceiling duct. That seemed to allow more airflow reducing the pressure on the system. I will most likely add another I still have plenty of flow. I also blocked the runs at the last vents.

I know this tread started by adding higher flow ducts. But leaving in tact and adding one I feel accomplished the same.
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Old 05-29-2018, 07:04 PM   #85
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I downloaded all of the service and installation data for my A/C unit (Mach 18) and found some performance information that may be relevant.

From ChillGrill literature
B. Registers
Supply (cold air) registers should have a minimum discharge area of 48 square inches per system, or 24 square inches per duct. A minimum of 6 is recommended.

From Airexcel's EVALUATING AIR CONDITIONER PERFORMANCE

1. Measure the evaporator temperature difference:
a. Open all discharge/ supply registers fully.
b. Tum the selector switch or wall thermostat to the HIGH COOL position.
c. Allow the air conditioner to run for at least a half an hour, longer if possible. This is necessary to fully cool the evaporator coil and saturate the unit with condensate water before beginning a temperature test.
d. Use a standard dial type or digital thermometer to measure the temperature of the air immediately entering the return air filter/grille of the air conditioner.
e. Measure and subtract the temperature of the air leaving the discharge/supply air louvers from the return air temperature. When you are testing a ducted air conditioner application be sure to measure the supply temperature at the closest register to the unit. Make sure the temperature sensing device is measuring supply air temperature only.
f. A properly running A/C unit should have a temperature difference of approximately 16 to 22 degrees. Slightly lower temperature differences are possible under extremely humid conditions. (The unit may have to run longer to remove moisture.) Greater temperature differences than 22 degrees are possible in hot dry weather.
NOTE: Restricted air flow over the evaporator may also cause greater than 22° temperature differences. In this case even though the temperature difference is greater the capacity would be less.

I checked mine and the difference is 33* so I may have a capacity problem. It cools well and the amperage is good so I'm good for now.
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Old 05-30-2018, 02:09 PM   #86
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I'm no HVAC expert but an a logical thinker. They don't build these for quality and function. They build them fast and with the same parts no matter what floor plan. With AC specifically, I watched enough factory videos to see they simply drop in a standard length duct and then hole-saw where they want the vent. So it's no surprise that the duct extends past.
What's bad is the lack of sealing off they do at duct joints, AC unit connections and vent openings. I resealed my duct openings and inside the AC unit. Unfortunately there's no way I can tell how well the duct sections are sealed.
And the further away from the unit, the weaker the flow. Even if I close all the vents but the farthest one, seems not that much stronger.
Like I said, no HVAC expert, but every house and business I been into, the AC ducting decreases in size/diameter the farther you get from the main unit. This creates higher flow. But the RV ducts don't seem to do that
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Old 05-31-2018, 09:09 AM   #87
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Checking out my AC to see if I can quiet it some and optimize its operation and I found a few things. Like someone else posted above the control box and wiring in the inlet plenum was just stuffed up in there and only secured with one screw that was too long so it was just flopping around. Also found the cutout for one of the registers had been left in the duct and was blocking the air flow.

One interesting thing I noticed in the manual for mine was a requirement for register location of 5-8 inches from the end of a duct. Obviously we are seeing much more than that in most cases. Mine have 30" or more of duct extending beyond the last register.

Attached is the requirements for my unit from the installation manual.Click image for larger version

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Old 05-31-2018, 10:12 AM   #88
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WOW! This tidbit could be the answer to my frustration with our A/C units in our 2016 Fuzion! Our rig is 43 ft with three A/C units. We spend lots of time in the Lake Havasu area in the summer time so we wanted to make sure we had adequate of A/C.

We have never felt we had decent cooling in the rig since day ONE! We rigged up a box in the bunk area to direct cool air into the main living area to no avail. Talked to the dealership on at least three occasions where they "tested" the cooling and said it was working fine.

I hope we can apply this fix!
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Old 06-03-2018, 07:18 PM   #89
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Originally Posted by nellie1289 View Post
Does anyone have a link to the foam they maybe used ? Amazon or Home Depot ?

That type of foam is called sill seal. It's used on the bottom of the sill plate that sits on the foundation wall of a home. https://www.lowes.com/pd/Dow-Sill-Se...t-L/1000172805


The thing I find interesting is in residential duct work the trunk needs to run a minimum of 12" beyond the last takeoff or the last register won't get very good air flow. It could be several feet longer and not cause an issue. Makes me wonder if the end of the run is closed off.
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Old 06-03-2018, 07:23 PM   #90
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Quote:
Originally Posted by BamaRam View Post
I downloaded all of the service and installation data for my A/C unit (Mach 18) and found some performance information that may be relevant.

From ChillGrill literature
B. Registers
Supply (cold air) registers should have a minimum discharge area of 48 square inches per system, or 24 square inches per duct. A minimum of 6 is recommended.

From Airexcel's EVALUATING AIR CONDITIONER PERFORMANCE

1. Measure the evaporator temperature difference:
a. Open all discharge/ supply registers fully.
b. Tum the selector switch or wall thermostat to the HIGH COOL position.
c. Allow the air conditioner to run for at least a half an hour, longer if possible. This is necessary to fully cool the evaporator coil and saturate the unit with condensate water before beginning a temperature test.
d. Use a standard dial type or digital thermometer to measure the temperature of the air immediately entering the return air filter/grille of the air conditioner.
e. Measure and subtract the temperature of the air leaving the discharge/supply air louvers from the return air temperature. When you are testing a ducted air conditioner application be sure to measure the supply temperature at the closest register to the unit. Make sure the temperature sensing device is measuring supply air temperature only.
f. A properly running A/C unit should have a temperature difference of approximately 16 to 22 degrees. Slightly lower temperature differences are possible under extremely humid conditions. (The unit may have to run longer to remove moisture.) Greater temperature differences than 22 degrees are possible in hot dry weather.
NOTE: Restricted air flow over the evaporator may also cause greater than 22° temperature differences. In this case even though the temperature difference is greater the capacity would be less.

I checked mine and the difference is 33* so I may have a capacity problem. It cools well and the amperage is good so I'm good for now.

Higher deltaT indicates lower airflow. The NOTE: above states that. Could be a dirty evap coil, not enough registers, dirty blower. The first two are most likely.
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Old 06-03-2018, 07:42 PM   #91
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Originally Posted by pitman44 View Post
Higher deltaT indicates lower airflow. The NOTE: above states that. Could be a dirty evap coil, not enough registers, dirty blower. The first two are most likely.
My unit is new and I have inspected it. It’s not dirty. I probably need more registers.
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Old 06-10-2018, 06:08 AM   #92
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Originally Posted by MisaLetet View Post
WOW! This tidbit could be the answer to my frustration with our A/C units in our 2016 Fuzion! Our rig is 43 ft with three A/C units. We spend lots of time in the Lake Havasu area in the summer time so we wanted to make sure we had adequate of A/C.

We have never felt we had decent cooling in the rig since day ONE! We rigged up a box in the bunk area to direct cool air into the main living area to no avail. Talked to the dealership on at least three occasions where they "tested" the cooling and said it was working fine.

I hope we can apply this fix!
Hi,
We have the unit shown in my signature block. I can tell you it will make a big difference! Yesterday, I got off my lazy butt and pulled the covers off all 3 AC units. First, I must say, I should've taken pictures, but I didn't. Anyhow, the first thing I noticed were the panels (not sure of the technical name) were just lying on their side inside the unit. In other words, the air was basically just staying up in the unit area and not really being forced into the vents. So, I untaped everything and retaped it, got things all nice and neat and lined up, reinstalled the covers, and cleaned the filters (which weren't dirty). Took a pool noodle and shoved it into each vent in the kitchen. The ducting system must have been crimped, because all of a sudden once I fired the units up, I had air coming from all 3 kitchen vents whereas, previously I had air only coming out of one! On the garage AC I noticed the heating element was not plugged in so I took care of that! Now, I know why the unit wouldn't generate any heat! Here in Texas it is hot, and I could tell the difference immediately. Sorry for the long post, but I hope this helps someone.
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Old 06-10-2018, 06:38 AM   #93
Jcdwing
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Originally Posted by BamaRam View Post
My unit is new and I have inspected it. It’s not dirty. I probably need more registers.


My unit was new as well. Mine changes were initiated by the reduction of noise.

Pulling the cover and taping all the re entry was a huge help. I have a dometic brisk air and with the cold air shower shower closed it was still so much pressure that it was squealing air from high pressure.

All I can say is adding one vent helped I may add another and the vents I purchased have the ability to be shut off as well.

Everyone’s results may vary. But this was a great help to reduce noise and cooling efficiency for me. Hope it helps someone else
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Old 06-23-2018, 05:29 PM   #94
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I just worked on mine today. I couldn’t get the trailer to cool down and it was getting very frustrating. Pulled the covers and found that the discharge air was blowing right back into the return and freezing up the evaporator. I also found many instances of poor taping in the ducts at the vents. Also found a dead end run of 8’ of ducting. Closed that off and redirected a couple of others. Finally it’s cooler inside than out and can actually feel the air moving. Fixed some leaks around one of the unit’s cover and that helped with noise. It’s a shame that the “professional” installation is this poor. Oh well, it’s still better than making a house payment.
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Old 07-04-2018, 08:49 PM   #95
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I've read through this thread a few times, I just want to reiterate a fix to collapsed ductwork in the air intake lines. So the quite cool system in my Montana isn't getting the airflow it needs. The intake ducts look squished down to 1/2 to 3/4 of an inch all the way to the ac unit. I checked with a buddy's bore scope camera. I'm just trying to figure out how to wedge a pvc pipe in there to open it up. It seems like I need something flexable enough, because of the tight angles and small holes I have to work with and the fact that it would have to run all the way to the unit from the intake grills. Anybody have any ideas?
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Old 07-13-2018, 09:50 PM   #96
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Note that on mine many of the ducted vents are connected together so you want to verify where they go before sealing any of them off.

Mine is a complete mess and gonna do a separate write up on it for anyone who has a Fuzion 420. No wonder why none of use can keep this model cool ...
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Old 07-14-2018, 03:50 AM   #97
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Another thing that helped with cooling in my old trailer is that when I put a NEW 15K BTU Dometic Duotherm Brisk II in to replace the old 13.5K BTU, I had to remove the bottom unit. You pull the four long bolts and the metal bottom comes off after taking off the plastic cover. I noticed the outflow from the A/C enters venting to the sides and the silver foil tape was very poorly installed from the factory that directs cold air into the vents to the front and rear of the trailer. Retaped these so that air wasn't escaping into the void in the roof and retaped the dam between the intake and outflow of air and the unit performs much better.
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Old 08-12-2018, 04:11 PM   #98
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I'm so glad more than a year later this tip is still coming in handy! When I originally posted I had no idea so many people would be interested.

A little update for us, while it did help significantly, we finally decided we needed a second a/c regardless. We decided we spent too much money buying our TT to not be 100% satisfied.

I will note that we saved some money by purchasing the new a/c off of amazon and then having CW to do the install. They charged $125 to install the one we bought, and we agreed $125 was worth my husband not having to fool with it!


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Any chance you have step by step instructions on how you did this? I’m afraid I’m going to break something lol!
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