Ducted AC accessing unit???

Question

My 5th wheel has 3 AC units. 2 of the unit blow strong and cold. The middle unit which primarily services the living room and kitchen doesn’t blow much at all although I can here that blower motor. Likewise and no suorise it doesn’t cool the living area. I have been running the bedroom and garage ACs to keep things cool.

I’d like to check the AC where it attaches to the duct and return but I have not inside access to the AC unit. The only unit that has a ceiling assembly is the garage. The bed room and living room units only have the return and AC registrars.

Question ... how do I even inspect this? Can it be done up top on the AC unit or does the ceiling panel have to come down? It’s in the 110+f range so I’m hoping I can get some advice before opening anything up.

We will likely take it to the dealer but are in the middle of a few projects and can’t easily move the rv right now.

Another note, there is a small amount of air flowing from 5he middle unit and it registers within 20 or so degrees colder than the intake temp. However, there is simply no airflow. I really need to be able to inspect the ducting at the unit to determine of the baffle between intake and exhaust is foobared.

Greetfull for any advice.

Thanks, Kirk.

wrgrs50s · Answer

I'm assuming its a newer unit because your saying there is no access from inside. I had a friend with a newer unit experiencing little airflow out the vents so they took off one of the vents to see if there was any obstruction they noticed that the lip on the vent itself was about an inch tall. This made the air have to ramp up over the top then down and out the vent. They replaced all of the vents with ones with a smaller lip that protruded into the duct and the airflow was good afterward and the rig cooled much better. You might pull a vent down and see if that could be an issue on yours. Also check each vent at the end and be sure there is a block installed to stop the flow at the end of the run. Some have reported that the air at the end of the run went into the front cap or attic area.

Inspect the ducting by removing vents and sticking your phone in the duct and taking a picture. That is how I checked mine and decided to block the end of each run.

rvexodus · Answer

wrgrs50s wrote:I'm assuming its a newer unit because your saying there is no access from inside. I had a friend with a newer unit experiencing little airflow out the vents so they took off one of the vents to see if there was any obstruction they noticed that the lip on the vent itself was about an inch tall. This made the air have to ramp up over the top then down and out the vent. They replaced all of the vents with ones with a smaller lip that protruded into the duct and the airflow was good afterward and the rig cooled much better. You might pull a vent down and see if that could be an issue on yours. Also check each vent at the end and be sure there is a block installed to stop the flow at the end of the run. Some have reported that the air at the end of the run went into the front cap or attic area.Inspect the ducting by removing vents and sticking your phone in the duct and taking a picture. That is how I checked mine and decided to block the end of each run.Yah mine stick up about 1/4 into the duct. Not as bad as most report. I really really hope my ducting isn’t cooling the cap. That would be disappointing. I do have a usb bore scope and have been poking around in the vents and haven’t seen anything to concerning yet. Did find a YouTube video where a guy installed a Coleman chillgrille and was able to resolve a few other leakage issues at the same time. I may want to do that down the road. It seems like if nothing else it gives you access to the underside of the AC. Kinda a bonus that it lets you quickly dump some cold air into the RV.

phillyg · Answer

Neither of my two units have inside access.  I'm assuming all servicing is done from the top.

rvexodus · Answer

phillyg wrote:Neither of my two units have inside access.  I'm assuming all servicing is done from the top.And I don’t want to pull an AC unit in 500000f weather only to find it has not issue :)It’s funny, we are wrapping up some projects like building an office in the garage, solar, lithium, inverters, cell boosters, wifi boosters etc so we don’t have to be doing these things once we hit the road. The whole point to having an RV is that we can get out of the heat .. or cold. For now we are stuck in it; finishing our projects and selling our house. Would be nice to know if all the rv systems are optimal. Maybe I’ll make it a phase n project to pull the ACs and tap up seams or even better add a chillgrille.

azdryheat · Answer

You're going to have to go onto the roof and pull the a/c unit, no other way. Mine also had very little blow to it. On the Voltage forum we discussed it and it turned out that the taping job was fouled up and the air was blowing into the ceiling rather out the vents. 4 lag bolts hold the unit to the roof. Remove the bolts and slide the unit aside. I found the metal tape wadded into a ball. The taping was applied over sawdust and failed to adhere (lack of quality control). Once I cleaned out the sawdust and re-taped the plenum interior the a/c blows very well.

One other point, the intake ducts in the ceiling can collapse and reduce airflow. I propped mine open with a 1" piece of short PVC.

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Ducted AC accessing unit???

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