Would upgrading the AC be worth it?

[The Gritz Carlton]

"One of the highest heat loads on any motorhome is the windshield, particularly new Class Cs with large slanted windshields"

IMO, the Class C's are the best design for reducing this type heat induction as the overhead cab shields the glass from the sun. My front windshield never sees sunlight. The worst configuration for this description is the Class A's whereby you're sitting in a "goldfish bowl" with the sun directly hitting the huge glass. The C's are designed by a commercial truck manufacturer with every working function installed at the time of delivery to the coach. Most A's have the entire front end...dash, A/C vents...everything manufactured by a coach company. Class C's don't come with auxiliary "fans" mounted over the driver and passenger seats. This is one of the top five reasons I went with a Super C vs. an A Class. The vast majority complain about the inability to keep the front end of the coach cool...especially while driving. This same heat induction is a problem when camping too. You need to close off the "glass dome" area around the front.

[kylecm]

Originally Posted by Oneilkeys

Adding a circular vent directly under the discharge makes a world of difference. It’s cheap and easy. There are several threads and instructions on how to do it.

I looked at this. My AC cover already has a vent.

Thanks

Chuck

[Chance]

Originally Posted by The Gritz Carlton

"One of the highest heat loads on any motorhome is the windshield, particularly new Class Cs with large slanted windshields"

IMO, the Class C's are the best design for reducing this type heat induction as the overhead cab shields the glass from the sun. My front windshield never sees sunlight. The worst configuration for this description is the Class A's whereby you're sitting in a "goldfish bowl" with the sun directly hitting the huge glass. The C's are designed by a commercial truck manufacturer with every working function installed at the time of delivery to the coach. Most A's have the entire front end...dash, A/C vents...everything manufactured by a coach company. Class C's don't come with auxiliary "fans" mounted over the driver and passenger seats. This is one of the top five reasons I went with a Super C vs. an A Class. The vast majority complain about the inability to keep the front end of the coach cool...especially while driving. This same heat induction is a problem when camping too. You need to close off the "glass dome" area around the front.

Does yours look like a Siesta?

[Chance]

Originally Posted by kylecm

I looked at this. My AC cover already has a vent.

Thanks

Chuck

Is this like your model?


Maybe a visual will help with the vent issue.

[The Gritz Carlton]

Chance...I would call that a B Class with a bump.

[Chance]

That Class C is the one asking for help in this thread as far as I know from reading first post.

[The Gritz Carlton]

Seems like it should work...but I'm not the one inside "feeling the heat". Someone posted a fix here to keep the cool air from jumping right over and back into the return. I think that may be the best solution. Seems a 13.5 should cool this coach sufficiently. Thanks for the visual...wasn't sure the model (or didn't take the time to find out).

[kylecm]

Originally Posted by Chance

Is this like your model?





Maybe a visual will help with the vent issue.

Yes that is exactly like mine.

[Chance]

As a very first step, have you tested the A/C to make sure it’s cooling to specification? Discharge air should be between 15~20 degrees F cooler than what’s going back into unit, normally assumed close to average temperature in RV.

If temperature difference is much colder, that can also signal a problem like insufficient air flow. If air temperature drop is too low, like say 10 F, it suggest unit is not delivering cooling capacity because of other reasons, like maybe low on refrigerant.


Just out of curiosity, do you notice a big difference when parked in shade versus parked in direct sun? It doesn’t take much sun through windows to overpower an RV A/C.

[Pete'sMH]

Originally Posted by SuperD

The round vent is available from Amazon, Camping World, and many other sources. Remove the four screws holding the ceiling cover in place and then remove the cover. Mark a spot in the center of the cover under where the AC exhaust is. Use the vent as a pattern and draw a circle where the vent will mount. Drill a 3/8” pilot hole and use a jigsaw with a fine tooth blade to cut out the circle you drew, take your time and keep the blade on the line, the plastic cuts very easily. Use four 1/2” #6 stainless panhead screws to mount the round vent. Reinstall the inside ceiling cover. You can goof off and still do the install in 30 min easily.



I’ve done several of these vents and they do make a difference. I leave the ducted vents open and use the round vent to direct air where I want it.



Here is the link to the vent on Amazon:

https://www.amazon.com/dp/B0095TEFNA...ing=UTF8&psc=1



If the link doesn’t work search for RV round air vent and then look for the vent made by JR Products.

This is the one I used:
https://www.rvupgradestore.com/JR-Pr...stable-Vent-p/
08-0171.htm

I had a 4 3/4 inch hole saw which is just a smidge too small. Enlarged the hole with a Dremel. I used 6-32 x 1/2 bolts which is overkill but it’s going to hold forever.

[petefoss]

Thanks guys

[DaveAk1ns]

Originally Posted by Chance

Does yours look like a Siesta?

New 23TR owner here, but I've learned a few things during some this summer's hot spells, and the #1 improvement was getting these sunshades off Amazon that fit the Transit perfectly. They solve 70% of the solar fish bowl heat issue, especially up front, and #2 is to run the Ford's AC asap and just until the interior temp drops and the roof AC can keep pace. Once we incorporated these 2 things, we've never been uncomfortable.

[Bob Denman]

I agree: it's more effective to keep the heat OUT, in the first place.

Otherwise, it's about like closing the hen-house door; after the fox is already inside!

[kylecm]

Great points. Here are a few times that we currently do or modifications we have done.

1. Pulled the ceiling down over the cab and insulated with Reflectix Insulation

2. Put up window sunshade set on the front windshield and side windows

3. blackout curtains we hung between the cabin and the coach, thus isolating the front of the vehicle.

These steps really made a difference but still trying to cool the coach a little more.

Thanks

[Bob Denman]

How about some fans to keep the air moving; that should help!

[abjbrtd]

Originally Posted by kylecm

Yes that is exactly like mine. Attachment 10905

Here's a link to a pretty good AC thread with some really good info for improving the Coleman AC unit, some of the info is generic enough to have some relevance to our Dometic unit.

http://www.thorforums.com/forums/f27...ice-12980.html

Before you make any changes you need to get some baseline temperature and air speed readings. BUT the first thing to do is close the vent on the AC unit it's for rapid cool down and should be closed after your MH starts to cool down.
With it closed you should feel an immediate improvement in the amount of air coming out of the front and rear vents.

Here are a couple of improvements I've done to our Dometic system.

1. Vents...blocking the duct at the very back and front vents before and after pictures.
This increased the air speed by 2 mph in the back and 1 mph in the front.

2. Cleaning up the MESS in the return duct.
I haven't measured the air speed at the vents, hopefully a big improvement. before and after

[blw2]

Originally Posted by abjbrtd

Here are a couple of improvements I've done to our Dometic system.

1. Vents...blocking the duct at the very back and front vents before and after pictures.
This increased the air speed by 2 mph in the back and 1 mph in the front

where do you think all that air was going before?

[Long & Winding road]

Originally Posted by blw2

where do you think all that air was going before?

Mine was going to an un-insulated bulkhead over the cockpit area so it wasnt doing any good for the interior at all. So this make a big diffence in my Axis.

I think mine was increased to 5+ mph up front. I could not believe it so I got my wife and asked here which vent I modified (only did one at this time so I could compare) and she said she could never feel the air on her face before (she is 5 foot 2) and thought it was great!.

Worth while and free mod.

[abjbrtd]

Originally Posted by blw2

where do you think all that air was going before?

Past the vent hitting the back/front caps building pressure and keeping a lot of the air from getting to the vent. Now all the air is coming out the vent.