A/C in Texas Heat

rkymntsno · 08-09-2019, 02:15 PM

Need some advice on this a/c. We arrived in Houston yesterday. Set up, got both a/cs running. It was 98 outside and the whisper quiet a/c in the living room wouldn't get below 80 until the sun went down. I figured it had to cool it down from the trip here. The back a/c runs better and cools better. It actually cycled on and off last night but not the front. It didn't get below 75. By the way, this is on a 2019 355 Mbqs.

So with the ac's running all night, today it's 98 outside and in the living room it's 83 degrees and climbing at 3:00 in the afternoon. Humidity is about 95%. I temp gunned the vents and it's blowing 49 degree air out on all vents.

Am I expecting too much out of the ac's with this heat and humidity? Or do you think there's an issue here? Doesn't seem to be any blockage in the vents, all air coming out good.

William_Tell46 · 08-09-2019, 02:56 PM

I've had similar issues.. Finally had a 3rd RV shop solve ( my issue).. The main AC had the intake and output plenum barrier loose under the on top access to your main AC unit. They re-aligned the divider and used HVAC foil sticky tape to set it in place.. And now for the 1st time in almost 2 years Mine cools and shuts off on the Main AC unit in even 95 degree weather.

The other thing you should check is the differential ( with that temperature gun) on the intake side of the whisper quiet and the output side..Should be between 18 and 22 degrees. So not the outside air temp.. but the intakes inside temp vs. the output side. I'm sure you also checked the intake filters and washed them.. Also if lifting the top off the rooftop A/C to check on the plenum divider.. you may as well clean and check the coils up on the roof. Even if 1 month old and you get around cottonwood trees , etc.. that can suck up and clog your coils and you will have similar problems.

Best wishes,

oldmanAZ · 08-09-2019, 02:58 PM

The AC units are generally expected to cool the air 20degF. So measure the temp of the air entering the AC unit and the temp exiting the AC unit and it should be ~20degF cooler at the exit.

If it is not, the next step would be checking more on the AC unit itself.
If it is, then - as long as doors are not opened too often - then see what you can do to keep the sun off and out of the trailer.

rkymntsno · 08-09-2019, 03:21 PM

Quote:

Originally Posted by oldmanAZ

The AC units are generally expected to cool the air 20degF. So measure the temp of the air entering the AC unit and the temp exiting the AC unit and it should be ~20degF cooler at the exit.

If it is not, the next step would be checking more on the AC unit itself.
If it is, then - as long as doors are not opened too often - then see what you can do to keep the sun off and out of the trailer.

Ok, I don't understand what you're saying. I'm not that mechanically inclined. The air entering the ac unit? Are you talking about on the roof? Where do I shoot the gun for the air entering and exiting the ac unit?

Magnolia Tom · 08-09-2019, 03:27 PM

Quote:

Originally Posted by rkymntsno

Ok, I don't understand what you're saying. I'm not that mechanically inclined. The air entering the ac unit? Are you talking about on the roof? Where do I shoot the gun for the air entering and exiting the ac unit?

Air enters from the air filter and exits from a register (air vent)

GraftonGuns · 08-09-2019, 03:31 PM

RKY, I had a very similar experience with mine. remove the four screws and ceiling diffusers one at a time. I found a gap between the ducting and 4 out of 8 diffusers. So basically I was cooling the gap between the ceiling and roof. I took care of that with white duct tape. No more problems. Also, The return air ducts had sawdust etc. on them I cleaned them out as well.

rkymntsno · 08-09-2019, 03:49 PM

Quote:

Originally Posted by GraftonGuns

RKY, I had a very similar experience with mine. remove the four screws and ceiling diffusers one at a time. I found a gap between the ducting and 4 out of 8 diffusers. So basically I was cooling the gap between the ceiling and roof. I took care of that with white duct tape. No more problems. Also, The return air ducts had sawdust etc. on them I cleaned them out as well.

Ok, what is a diffuser? The vent? So check each vent to make sure no gaps in the ductwork?

rkymntsno · 08-09-2019, 03:49 PM

Quote:

Originally Posted by Magnolia Tom

Air enters from the air filter and exits from a register (air vent)

Ok, got that. I have two registers. I'll check that with the temp gun.

rkymntsno · 08-09-2019, 03:51 PM

Quote:

Originally Posted by oldmanAZ

The AC units are generally expected to cool the air 20degF. So measure the temp of the air entering the AC unit and the temp exiting the AC unit and it should be ~20degF cooler at the exit.

If it is not, the next step would be checking more on the AC unit itself.
If it is, then - as long as doors are not opened too often - then see what you can do to keep the sun off and out of the trailer.

Ok, at the registers, intake, it's 82 degrees. Coming out of the vents, it's 59 degrees.

Riverman · 08-09-2019, 05:25 PM

23 degrees between the supply and return is good. One more thing, I got on my roof with a water hose and coil cleaner. Cleaned the evaporator and condenser coils real good and my unit now is cooling much better. It's just hot weather.

RogerR · 08-09-2019, 05:33 PM

If you don't have double pane insulated windows than your are letting in a huge amount of heat. My solution was buying a roll of Reflectix aluminum faced bubble wrap stuff. Meant to be used around ductwork in the attic or such. But I cut a piece for each window and leave it in on the off season to prevent interior heating and fading. But found out it really works great to keep the place cool in hot sun and uses less heat in cold conditions when we camped in the Rockies in October. Now I leave it between the shades and the glass until we camp somewhere and take it down as appropriate.

AKRUEBBE · 08-09-2019, 05:38 PM

I think the double pane windows really help. The highest temp we've been in so far has been 96 and have no problems keeping the coach as cool as we want. Will be heading to Texas in a couple of weeks and will see if my theory still holds!

rkymntsno · 08-09-2019, 05:44 PM

Thanks for all the comments guys. I pulled two of the four diffusers and all taping is good. Good airflow on all four. And there's been 49 degree air coming out of the vents. Turns out the intake air register filters (sponge material) wasn't that clean and it's only four months old. Washed them so it can't hurt. See how the rest of the week goes.

rkymntsno · 08-09-2019, 05:45 PM

Quote:

Originally Posted by AKRUEBBE

I think the double pane windows really help. The highest temp we've been in so far has been 96 and have no problems keeping the coach as cool as we want. Will be heading to Texas in a couple of weeks and will see if my theory still holds!

We're at 100 degrees and 100% humidity. If that doesn't test your system nothing will!

AKRUEBBE · 08-09-2019, 05:55 PM

Quote:

Originally Posted by rkymntsno

We're at 100 degrees and 100% humidity. If that doesn't test your system nothing will!

Looking forward to the test

Will be in Sanger, TX for a week before heading to Louisiana.

oldmanAZ · 08-09-2019, 07:18 PM

Quote:

Originally Posted by rkymntsno

Ok, at the registers, intake, it's 82 degrees. Coming out of the vents, it's 59 degrees.

So it's 23degF cooler coming out of the AC unit than going in to it.

You'll need to look at ways to keep the sun out of and/or off of your trailer.
-Do you have toppers on your slides?

-Do you have dual pane windows?
-Do you have skylights?
-Do your ceiling vents have vent covers?

rkymntsno · 08-10-2019, 07:17 AM

Quote:

Originally Posted by AKRUEBBE

Looking forward to the test

Will be in Sanger, TX for a week before heading to Louisiana.

Stop by Rumpy's in Gainesville if you're coming down that way. It's a gas station/bakery. Excellent baked goods. Just off I-35.

rkymntsno · 08-10-2019, 07:25 AM

Quote:

Originally Posted by oldmanAZ

So it's 23degF cooler coming out of the AC unit than going in to it.

You'll need to look at ways to keep the sun out of and/or off of your trailer.
-Do you have toppers on your slides?

-Do you have dual pane windows?
-Do you have skylights?
-Do your ceiling vents have vent covers?

Ok, so you guys think it's cooling like it's supposed to? No dual panes, frameless. One skylight in the bathroom, vent in bathroom is covered with cushion. Ceiling vents have vent covers? What kind of covers are you talking about? No slide toppers. It sounds like it's just too fricken hot. I do have reflectix that I need to put up. It's not doing me any good in my garage right now. I'll get it ready for the next trip, lol. Thanks for the input.

DonaandDon · 08-10-2019, 07:30 AM

My second step, up to the bedroom is the furnace cold air return. The grill cover is removable with six removable screws. A piece of cardboard will prevent cooler air escaping from your living room.

Additionally, my vents in the cargo areas have the ability to close so as not to cool or heat those areas too. While in the cargo storage areas look around and use your heat gun to find potential areas that my need sealing. I found one area around the flushing/outside shower station.

AKRUEBBE · 08-10-2019, 07:31 AM

Quote:

Originally Posted by rkymntsno

Stop by Rumpy's in Gainesville if you're coming down that way. It's a gas station/bakery. Excellent baked goods. Just off I-35.

Passing through Gainesville.............will put in on our list...........thanks!

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