Air conditioner question - RV-Dreams Community Forum

cherylbrv · RV-Dreams Family Member

Air conditioner question

Lucky Mike · RV-Dreams Family Member

something to think about.....the superheat or condenser on your roof is 25 to 40 degrees hotter than the outside temp....if there is alot of humidity outside the condenser cannot cool quick enough to dissipate which means when the freon cycles it cannot remove as much heat as it should from inside

cherylbrv · RV-Dreams Family Member

Thanks, Mike. Does this mean there really isn't anything we can do when in high heat and humidity?

MPMomof3 · RV-Dreams Family Member

Have you tried a dehumidifier and/or fan? If you are boondocking, damprid may also help with the humidity. Hope this helps. Walmart has damprid in their camping section.

Alie and Jims Carrilite · RV-Dreams Family Member

Cherylbrv- Have your husband take the cover off the unit and spray the coils with a product called "Coil Kleener" or similar. And hose out the fins. If their clogged with debris then you lose a significant amount of cooling power.
We leave our main unit, 15k heat pump, on 68* on High fan. If we put it on low fan the condenser freezes up and we get warm air.
Our front bedroom unit is a 13.5k standard unit that during the day is on 68* and at night usually moves up to 74* or so. Less noisy that way. Both units are ducted.
Because we are in south east Texas right now, we have the reflective material in all the big windows, with the small side windows uncovered for some light. It helps a lot.
Now with all this said and done, our AC units can keep us at 78* or less at 103*. which it has been just about every day since mid June.
If the air exiting a vent is 20-25* cooler than the air entering the AC return then its operating normally. If its not then it might need a recharge or as said above, its dirty.

Will the unit cool the RV at night when there is no solar heating to deal with?

-- Edited by Alie and Jims Carrilite on Sunday 24th of August 2014 08:16:50 PM

MPMomof3 · RV-Dreams Family Member

MPMomof3 wrote:
Have you tried a dehumidifier and/or fan? If you are boondocking, damprid may also help with the humidity. Hope this helps. Walmart has damprid in their camping section.

I forgot to mention that we had our air conditioner freeze up once. We think it was because it was trying to work too hard. You may also try other methods of reducing heat and moisture inside your rig such as not opening and closing the doors any more than you have to, cooking for shorter times and taking short showers in addition to what I mentioned above. Hope this helps. I'm glad some other people were able to give you advice on the outside issues. smile

The Bear II · RV-Dreams Family Member

114 - 25 = 89 degrees....hot
94 - 25 = 69 degrees ....cooler

Sounds like it was working OK it's just hot outside.

When we are in those types of temps we leave the A/C on 24/7 and if we happen to get cold we cover up rather than adjust the thermostat. We want it as cold as possible and try to keep all the surfaces cold to help keep it cold as it heats up outside.

All blinds are down and turned so no sun comes in. Awnings are deployed and the door stays shut as much as possible, no in and out.

We use portable fans to blow cooler air directly at us. We can usually keep it comfortable enough to just sit and not do anything.

-- Edited by The Bear II on Monday 25th of August 2014 09:12:53 AM

cherylbrv · RV-Dreams Family Member

Thanks for all the great advice. We had some t'storms pass thru last night which broke the heat wave. A/c seems to be working just fine right now, so I suspect it was just hard to keep up with the heat. Your tips are very good.

TRAILERKING · RV-Dreams Family Member

Also be sure the filter is clean and have good air flow. Restricted air flow can cause a "Freeze-Up".....
Even if it's hot outside.

Terry and Jo · RV-Dreams Family Member

Per Alie and Jim as well as Trailerking, both maintenance things are helpful to the air conditioners. In our case, I get on top with an air nozzle for our air compressor and blow out the fins in the air conditioner every Spring. I'll have to look into the "Coil Cleaner" stuff to see if that makes it easier.

I also pull out the a/c return filters from the ceiling each Spring and clean them. However, I did improve that job by "modifying" how our return air grates are mounted to the ceiling. When manufactured, they just use two screws for each grate and fasten them to the ceiling material. I've modified by fastening a small block of wood at each place and putting in screws that have wood screw threads on one end and machine threads on the other. Then, with the new screws in place, I used knurled knobs to hold the grate in place. Now, all I have to do is remove the two knurled knobs on each grate instead of having to remove the entire screw.

Terry

RickandJanice · RV-Dreams Family Member

Before it gets hot again, as already suggested,clean the cooling fins and the cold air return filters located on the ceiling. Then next time the heat and humidity gets high, if it still does not seem adequate, try setting the A/C fan on h\High instead of Auto at the thermostat. Could be that the A/C is just freezing up in the high heat / humidity and running the fan on high constantly will help prevent that.

If you already have two A/C's on the roof, then please just ignore this suggestion but if you only have one A/C, you may need to consider adding a second one, especially on a 36' unit. DRV has already ran the wire and ducting in the ceiling to install one in the bedroom. You will just need to find someone that knows DRV units and where to install the ducted units or you may end up with a cheaper direct duct that in much noisier. The technician will also need to know which board to order from Dometic to make a new A/C communicate with the older one or neither will work. If you need to do this, I highly recommend Interstate RV in Howe, Indiana as Paul Cross knows both DRV and Dometic.

Clay L · RV-Dreams Family Member

The Bear II wrote:
114 - 25 = 89 degrees....hot
94 - 25 = 69 degrees ....cooler

Sounds like it was working OK it's just hot outside.

When we are in those types of temps we leave the A/C on 24/7 and if we happen to get cold we cover up rather than adjust the thermostat. We want it as cold as possible and try to keep all the surfaces cold to help keep it cold as it heats up outside.

All blinds are down and turned so no sun comes in. Awnings are deployed and the door stays shut as much as possible, no in and out.

We use portable fans to blow cooler air directly at us. We can usually keep it comfortable enough to just sit and not do anything.

-- Edited by The Bear II on Monday 25th of August 2014 09:12:53 AM

The 20 to 25 degree temp difference is not between the outside air temp and the air coming out of the ac, but as Rick said above it is between the inside air going into the ac and the ac output. All RVs with roof top acs that I have seen recirculate the inside air and do not take in outside air.

Bill and Linda · RV-Dreams Family Member

As pertaining to comments about have 2 AC units in rigs 36’ feet and larger. Yes indeed – especially 5^th wheels due to the bedroom ceiling being lower than the living area. (Lower ceilings = ~~warmer~~ hotter room.)

This is one of those things people have different opinions about. But if you are in higher temps – and by higher I mean higher 80’s and up – you need two AC units. That is unless you enjoy being uncomfortable. You don’t necessarily need them all 24 hours. But as temps reach into the 90’s it is just pretty difficult for one AC to keep up – especially in the bed room with one AC located in the living area.

For those reading along and considering a new or used RV for that manner, please consider getting the second AC unit. You will need it and besides they do go bad and when one fails you have another one. We’ve had an AC unit fail in 100 plus temps and I can assure you we were very glad to have the second one with interconnected ducts. This just isn’t a good place to save on purchase costs, IMO.

cherylbrv · RV-Dreams Family Member

I do have 2 a/c units. And that explains why the bedroom always does seem to be a little bit warmer!

TRAILERKING · RV-Dreams Family Member

cherylbrv wrote:
I do have 2 a/c units. And that explains why the bedroom always does seem to be a little bit warmer!

Bedrooms are ALWAYS a little warmer........................... biggrin

BiggarView · RV-Dreams Family Member

Bill and Linda wrote:
...That is unless you enjoy being uncomfortable....

If you enjoyed it, you wouldn't be uncomfortable. biggrin

Sorry Bill, I couldn't resist.

Brian

BiggarView · RV-Dreams Family Member

Sort of off topic a bit, but some thoughts on A/C placement. Being on the roof, they are exposed to the brutal heat of the sun. I know Winnebago had Basement AC for a few years about a decade ago on some of their MHs, couldn't that be done on a 5er? Not only would it lower the height of the rig, it would make servicing them is some respects easier and safer. It also occurs to me that having the AC unit(s) down near ground level would let them run cooler as they would not be fighting the baking heat of the sun. I get the whole AC on the roof 'cause it's less expensive to put them on the roof vs built into the frame or lower body area... but is that the only reason the mfrs locate them on the roof?

Brian

SnowGypsy · RV-Dreams Family Member

We got an electric fan to use for our bunk area in our TT which helped a lot: https://www.lehmans.com/p-364-electric-doorway-fan.aspx and I see that Vornado is making something similar: http://www.vornado.com/circulators/V103-Under-Cabinet-Circulator and while I cannot speak for how good the Vornado is, we have one of the smaller fans and also a humidifier which we really like. I do think that fans help the AC by drying the air a little bite, maybe not but in my mind it does but science might prove me wrong.

Talensnana · RV-Dreams Family Member

My husband has the Vornado fan which is shown in the link. He loves it. He has it blowing on him at night. Keeps him cooler and doesn't make me cold.

Terry and Jo · RV-Dreams Family Member

biggaRView wrote:
Sort of off topic a bit, but some thoughts on A/C placement. Being on the roof, they are exposed to the brutal heat of the sun. I know Winnebago had Basement AC for a few years about a decade ago on some of their MHs, couldn't that be done on a 5er? Not only would it lower the height of the rig, it would make servicing them is some respects easier and safer. It also occurs to me that having the AC unit(s) down near ground level would let them run cooler as they would not be fighting the baking heat of the sun. I get the whole AC on the roof 'cause it's less expensive to put them on the roof vs built into the frame or lower body area... but is that the only reason the mfrs locate them on the roof?
Brian

Just as a thought about that idea, wouldn't a/c units at a low point on the coach be more susceptible to pulling in dust from passing vehicles? Perhaps even other crud as one is driving down the road?

Terry

cheryls-other-half · RV-Dreams Family Member

(Take two: Mitch (...) snips and asks/clarifies [with some] pictures...)

Terry and Jo wrote:
(AC) maintenance things :
..., get on top with an air nozzle for our air compressor and blow out the fins in the air conditioner every Spring.
--> Quite doable, had to already replace both the dometic plastic ac covers on top. Sorry too hot right now to blow it out or take pictures.
...I also pull out the a/c return filters from the ceiling each Spring and clean them.
...did improve that job by "modifying" how our return air grates are mounted to the ceiling.
When manufactured (by DRV), they use two screws for each grate and fasten them to the ceiling material.
..we modified: (us too) by fastening a small block of wood at each place and putting in screws that have wood screw threads on one end and machine threads on the other. Then, with the new screws in place, I used knurled knobs to hold the grate in place. Now, all I have to do is remove the two knurled knobs on each grate instead of having to remove the entire screw.
Photo 1: finished return air vent, as modified in my DRV, assembled to ceiling:
OK. My dumb 'newbie' question (I know, no question is ever dumb..)
These are the ONLY filters in the dometic (DRV) A/C system?
The black material measures 8"X12" Does anyone make a furnace filter that size? It would be even more effective!
Photo 2: dis-assembled vent, with DIRTY filter material:
Photo 3: dis-assembled vent, with cleaned filter material:

Oh, and here's a "Doy alert", as caught by my dear other half. MAKE sure to CLEAN them OUTSIDE, so the gook does NOT go back into the filter!
cheers

-- Edited by cheryls-other-half on Thursday 28th of August 2014 12:49:56 PM

BiggarView · RV-Dreams Family Member

Terry and Jo wrote:
biggaRView wrote:
Sort of off topic a bit, but some thoughts on A/C placement. Being on the roof, they are exposed to the brutal heat of the sun. I know Winnebago had Basement AC for a few years about a decade ago on some of their MHs, couldn't that be done on a 5er? Not only would it lower the height of the rig, it would make servicing them is some respects easier and safer. It also occurs to me that having the AC unit(s) down near ground level would let them run cooler as they would not be fighting the baking heat of the sun. I get the whole AC on the roof 'cause it's less expensive to put them on the roof vs built into the frame or lower body area... but is that the only reason the mfrs locate them on the roof?
Brian
Just as a thought about that idea, wouldn't a/c units at a low point on the coach be more susceptible to pulling in dust from passing vehicles? Perhaps even other crud as one is driving down the road?
Terry

Hadn't thought of that. One could always shut down the AC while moving from one location to another and possibly cover the areas prone to "crud" or dust while in transit.

JPBeck · RV-Dreams Community Member

MPMomof3 wrote:
Have you tried a dehumidifier and/or fan? If you are boondocking, damprid may also help with the humidity. Hope this helps. Walmart has damprid in their camping section.

Wouldn't a dehumidifier just add more heat to the trailer? The one we have in our basement heats up one section of our like an oven.

SnowGypsy · RV-Dreams Family Member

We either buy a better filter or buy the window air conditioner filters that Wal-Mart has and cut them to fit so we always have a clean and dry filter. They get dirty very quickly.

The Junkman · RV-Dreams Family Member

Add one of those 15k btu floor ac that sit on the floor. They vent out a window too..

Cummins12V98 · RV-Dreams Family Member

This WILL make your AC units work MUCH better.

Our MS ia a 07.5 36SB3 with two Penguin AC units. I had a capacitor go out a while back and when I had the cover off I noticed the foam that is supposed to keep out hot air was not sealing in many places. So I bought two foam kits. The foam was stuck to the covers from the factory. I removed all the old foam then installed the new foam to the AC unit it's self.

WALA in well over 100 degree weather we are now comfortable.

The Junkman · RV-Dreams Family Member

For the Eastern southern folks who have T-stats and multiple ac's..

Where do you set your t stat to be comfortable in the southern heat and humidity?

Just getting into out rv.. Tech here says to run them manual on with fan on med or high to avoid freeze up. Been doing that.. but fans are make noise, if you like it quiet, and they run all the time in manual mode... At night I have been setting it on auto.. and it hardly comes on and off..which is good. It's always set at 70.

Also, I have 3 ac's.. and mostly been running all 3 during the day.. just 2 at night.

Temp is always good .. no issues.. Was going to add a dehumidifier.. but now understand that is what the ac does..so one is not needed.

I imagine I can open the windows in the fall, and hit the roof exhaust fans to suck air in.. just not cool enough yet. even at night...

Bill and Linda · RV-Dreams Family Member

Steve:

IMO, running the AC circulation fan all the time (i.e. not in auto) just makes the trailer hotter and more humid. Why? Because IF you have ducted air then you have the heat in / of the roof is transferred into the ducts. Without the compressor running the air you are circulating is actually being heated by the roof heat some regardless of the amount of roof insulation. This also increases humidity which is what makes us sometimes feel hot even at 73 degrees. We set the temps where we are comfortable and that varies with humidity – especially in the southeast. Our settings will vary considerably with outside temps.

IMO, if the AC’s require the fans to be running “all the time” because they freeze up something is wrong with the installation or the AC units themselves. I’m not saying I’ve never had freeze up, but only when it was cold(er) outside, not hot.

At night, because our ducts are interconnected, (both AC’s feed all of the trailer) I usually use the living room AC only but set the bedroom unit a degree or two above the living room just in case the bedroom temps do go up at night for whatever reason. The bedroom in a 5er is always the hottest room because of the lower ceilings as you know.

Bill

BiggarView · RV-Dreams Family Member

That, and the fact that most 5er bedrooms are also at the front where it is higher than the rest of the coach... heat rises.

Brian

Terry and Jo · RV-Dreams Family Member

When we were in Oklahoma, we had heats up to 115 degrees, plus had the humidity, although not as high as near the coasts. We've always ran our air conditioner's fans on "auto" instead of "manual" and never had a problem. However, our 2010 has different a/c units than the new ones. From what "some folks" have said, the newer a/c units aren't as good as the older ones.

Terry

Bill and Linda · RV-Dreams Family Member

Terry and Jo wrote:
From what "some folks" have said, the newer a/c units aren't as good as the older ones.
Terry

Amen to that, Terry. But not due to freezing up. due to noise caused by the regulations that require them to be so efficient and therefore, according to the people that make them, more noisy. Ours are "OK" now, but not as good as the old ones. But they cool really well.

I'd take the ones from our 2007 back in a minute. Not the RV manufacture's fault. The new regulations.

On edit, let me add that the new ones use the same amps as the old ones. Can see that on our PI meter. Maybe they run less due to the new regulations don't know. But they pull the same amps at the same voltage.

Bill

-- Edited by Bill and Linda on Friday 5th of September 2014 01:57:26 PM

The Junkman · RV-Dreams Family Member

Been running on auto at 70 in the new property here in FL.. No issues. Have all 3 on auto.. They seem to go on and off as needed.. by zone.

I think I'm good to go.. good thing. The blowing of the air is a little noisy for me with all 3 on med..

Thanks.

Glenn West · RV-Dreams Family Member

Unfortunately all the acs/heatpumps made in the last 10 years are noisy. Coleman is the quietest of them, by a lot, but still louder than the older units. I dread the day we have to replace the ones in our Teton. They are quiet.

The Junkman · RV-Dreams Family Member

Glenn West wrote:
Unfortunately all the acs/heatpumps made in the last 10 years are noisy. Coleman is the quietest of them, by a lot, but still louder than the older units. I dread the day we have to replace the ones in our Teton. They are quiet.

It's not the ac unit that is noisy to me.. It's the air runnning out the vents.. With all 3 ac's running w/ fan set to med.. I have to turn the TV volume up a bit.. I hate that..

I think this rv needs bigger vents...

Glenn West · RV-Dreams Family Member

Our previous camper was a 2006 Mobile Suites. It had the ac/heat pumps with the new freon in them. they were very loud and caused us to turn tv up loud enough that it interfered with conversation. Our current Teton is a 2003, old style unit. They are very quiet. We can talk normal and can turn tv down to a level one can sleep and other hear tv. Like I posted before, dread the day they need replacing. This is nice after having the DRV newer units.