Ok here is a new one. New one to me at least. We just got a new kz venom toy hauler earlier this year. We’ve been doing a number of upgrades from solar to turning the garage into an office while trying to get our house ready for sale. The 5th wheel is parked on my dads property in the northwest valley. I only get 15a from his outlet and use my inverters and lithium bank as well as solar to run 2 of my 3 air conditioners. In 110+ weather two air conditioners can’t keep this enormous rv cool and temps inside can go into the 90s.So, I’m sitting on the throan today and cranked on the fantastic fan for a little white noise and ventilation. You have all been there right? Anyhow, I noticed that the AC duct in the bathroom actually started blowing harder and it started to cool down. Ok let’s take this out of the lab and trial it in the real world.I then opened the fantastic fan in the kitchen, cracked a window and immediately felt the ambient air get cooler. Ducts that barely blew were flowing like never before. Within about 15-20m the inside temp dropped from 92 to 87. We were packing up to head back to the house so I didn’t play much more with the idea. However, at one point I closed the window and cranked the fan from 20% up to around 80% and it looked like it was starting to warm up. There is likely a sweet spot here.I think there’s one of two things happening here or maybe a combination. Static pressure ... eg, heavy warm air can make it harder for the AC to blow and circulate air. Also, as many know when they have cranked on their roof vents with no windows open the fans are powerful enough to pull air from anywhere including grey and black tanks. I’m guessing the fan is actually improving airflow from the AC ducts much like a booster or inline fan would in a residential situation.I’ll play around with this to see just how far I can pull temps down running just two AC units but thought I would share this with anyone that is having problems cooling their rv in hot as heck weather. Even a few degrees can make ia big difference. Curious, has anyone else experienced this effect?Thanks, Kirk

Sounds to me like you need a little more info, hopefully I can help. My father has a venom with three ac's, and this is actually pretty easy to explain why it's happening. Though, it would help if you had a couple more bits of information. for one, if you're trailer is at 90 degrees with two ac's running, something's wrong, it's 98 today in south texas, and we got theres down to 78. That said, one is on a thermostat, two are knobs on the cooler. The particular one with knobs in the bedroom says it's on, but if you read the manual, it's actually not. Your FAN will run on just 12volts, the compressor will not. Have you actually verified that you're getting cold air out of the actual AC, and the fan isn't just running. For two, if that is happening, you're likely causing damage, they had to replace the unit because it burnt out the compressor, trying to run 2 ac units on so little power seems to be an expensive problem, at least with the venom they own. I'm not sure how you're turning 15A into enough starting amps, let alone running amps to power nearly 30 amps worth of AC units. If' im not mistaken, two of the three you have are 15k units, they take quite a bit to start, and just a little less to run, that's not including all the others you're using. Though, they don't have solar, so I can't speak to that. Back to my initial statement though, 90 degrees would be semi expected, if it's actually 110 degrees outside, very few places in the states are actually seeing those temps right now, if you're unlucky enough to get in one, then that's 20 degrees lower than the outside temps. That's about what you can expect, adding another AC won't really change that, these units can only lower the temp by about 20 degrees, it wouldn't matter if you had 100 ac units, if the temperature coming out of them is only 20 degrees lower than the ambient temp, then that's as low as it's going to get, period. As for why the fans cause it to feel colder, you already nailed that one. At 110 degrees, the static pressure in your cabin is likely extremely high, nauseating almost. It's hard to say for sure, because so few people actually get to expereince such extreme temperatures while in an RV, so what you're seeing is extremely uncommon. Nonetheless though, i think you're right with that one, super hot air is extremely dense, though, depending on the unit, and where the intake is, could stop that. I'm assuming they are all internally inducted, thus using that super hot, likely humid air. I know it's dry outside, but with a 20 degree difference between inside and outside, i'm going to assume your humidity levels are off the charts. With all of that said, what you're describing isn't all that bad, 20 degrees is decent. I said initially something might be wrong, because it's hard to fathom actual 110 degrees beating down on a big metal box.Don't forget to take into account the super hot dense air will rise up, so if you're in a small-ish room with a single duct ( like a bathroom ), then you start to push hot air out, you'll feel a noticeable increase in ambient temperature, increase as in, a change, not a literal increase of temperature literally. When you do this on a large scale, the intake can breath more heavily, thus resulting in a higher blower. Unfortunately, with the windows open, you might blow faster, but you likely won't achieve an actual lower temperature, the temperature is static in the sense it's always going to be the same, relative to the ambient temperature outside. so while you can achieve the affects of a cooler trailer, based on logic alone, you can't actually get those, at least nothing that would be worthwhile.

rvexodus wrote:Curious, has anyone else experienced this effect?I offered similar advice just within the past 24hrs to a fellow who posted he was having trouble getting his camper to cool down.Not only do you allow more air into the camper, you are REMOVING the hottest air from the ceiling with the fan.Ever notice in your car how the fan in the dash blows more air when you open a rear vent? Or how much faster it cools down on a hot day when you lower the rear windows a bit and have the dash blowing A/C on high? Get the hottest air out first, provide cooler air to the A/C to further cool, and reduce any inside pressure by allowing a good exhaust while you replace that air with ever cooler air.

he said the 15amp shore power and his solar are supplying charge to his 'Lithium battery bankhe is running the a/c from inverter powerI assume,, he has a deficit during the day using more power from batteries than is generated, and gets the batteries fully charged overnight ?

The real solution is to pull 50 amp power to the RV.Otherwise the air just recirculates so the vent fan may concentrate cool air in one area but in the end is pulling heat in somewhere else. RVs are generally not well sealed. If you have a hot box from driving all day it may help to push some of the hottest air out. Soon you need to just close up and let it work.

MrWizard wrote:he said the 15amp shore power and his solar are supplying charge to his 'Lithium battery bankhe is running the a/c from inverter powerI assume,, he has a deficit during the day using more power from batteries than is generated, and gets the batteries fully charged overnight ?He's running TWO ac's from the inverter. I don't think it matters how many batteries you have, that's a lot of power. I'm pretty sure he's not even running the compressor, and it's just the fan as someone else pointed out. It happens on our venom toyhauler all the time.

Air conditioners ... open windows to cool things down?

Durb
Explorer
Jul 08, 2017
pnichols wrote:
The OP's air conditioining may not be operating as a "closed system" ... in that the A/C's air intake is not 100% circulating only air from the house interior. In other words some of the A/C's intake air is continuously made up of some new (hot) outside air that is leaking in. This means that there is an "outside air leak" somewhere in the A/C's intake system.

If the OP's A/C system is otherwise operating properly with no intake air leaks and with all windows/vents closed and is 100% using "recirculated intake air" like it's supposed to be, then it's outlet air into the interior is always around 20 degrees lower than it's intake air. Since the intake air is supposed to be 100% coming from the interior of the house, it's outlet air temperature is always getting colder and colder until limited by the thermistat setting ... THAT IS IF the BTU capacity of the A/C system is great enough to, at any expected outside temperature, swamp out the continual heat gain from the outside through the ceiling, the walls, and the floors.

One should always buy a new RV with the maximum BTU size air conditioning system(s) offered - just in case they find themselves having to camp in unexpectedly high temperatures. IMHO, that's part of the "self-containment" goal of an RV.

BTW, a leak in the intake system would also explain why opening some windows would help with cooling from an air-leaking system. The slight pressure increase in the interior - as maintained by the air conditioning system's fan(s) trying to pull in some air from the outside, when they shouldn't be - would be relieved by the open window(s)r - thus permitting flow of some extra cooled air from the leak on out the open window(s).

I Have the same problem with my Carrier air conditioner. The best it could do was lower the trailer to 88 when 92 outside. This post inspired me to get on the roof and pull off the cover and shroud. I had a spot where the coper tubing enters the plenum where hot air could come in but it was minor and I fixed it with some foam tape.

I did notice there was a large opening between the intake and output sides within the air conditioner house portion. The installer stuck a piece of foam in front of the gap and not sealing it. The fan was just circulating air within the unit not pulling it over the cooling coils and not pushing it out the vents. I sealed the gap thoroughly. Turned it on and I now have about 3 times the air volume coming out of the vents and it is cold.

I'm excited to test the air conditioner in a couple of weeks on our trip to some hot locations. Thank you pnichols.
Grit_dog
Navigator
Jul 08, 2017
Maybe explained already. Didn't read 3 pages, but yes the OPs experience is valid.
Cold air sinks, heat rises, opens roof vents and/or a fan and you're exhausting hot air and lowering the air pressure the fan on the AC is fighting to blow air into the camper.
Assume an air tight space. Pretty soon the space is going to pressurize to the same pressure the the blower is capable of producing and then no more air flow. If the camper is closed up then you get less air flow.
That's why re circ on the car cents blow harder. Not trying to pressurize the cabin with "new" air. Same effect by rolling down a window in normal mode.
rvexodus
Explorer
Jul 08, 2017
Durb wrote:
pnichols wrote:
The OP's air conditioining may not be operating as a "closed system" ... in that the A/C's air intake is not 100% circulating only air from the house interior. In other words some of the A/C's intake air is continuously made up of some new (hot) outside air that is leaking in. This means that there is an "outside air leak" somewhere in the A/C's intake system.

If the OP's A/C system is otherwise operating properly with no intake air leaks and with all windows/vents closed and is 100% using "recirculated intake air" like it's supposed to be, then it's outlet air into the interior is always around 20 degrees lower than it's intake air. Since the intake air is supposed to be 100% coming from the interior of the house, it's outlet air temperature is always getting colder and colder until limited by the thermistat setting ... THAT IS IF the BTU capacity of the A/C system is great enough to, at any expected outside temperature, swamp out the continual heat gain from the outside through the ceiling, the walls, and the floors.

One should always buy a new RV with the maximum BTU size air conditioning system(s) offered - just in case they find themselves having to camp in unexpectedly high temperatures. IMHO, that's part of the "self-containment" goal of an RV.

BTW, a leak in the intake system would also explain why opening some windows would help with cooling from an air-leaking system. The slight pressure increase in the interior - as maintained by the air conditioning system's fan(s) trying to pull in some air from the outside, when they shouldn't be - would be relieved by the open window(s)r - thus permitting flow of some extra cooled air from the leak on out the open window(s).

I Have the same problem with my Carrier air conditioner. The best it could do was lower the trailer to 88 when 92 outside. This post inspired me to get on the roof and pull off the cover and shroud. I had a spot where the coper tubing enters the plenum where hot air could come in but it was minor and I fixed it with some foam tape.

I did notice there was a large opening between the intake and output sides within the air conditioner house portion. The installer stuck a piece of foam in front of the gap and not sealing it. The fan was just circulating air within the unit not pulling it over the cooling coils and not pushing it out the vents. I sealed the gap thoroughly. Turned it on and I now have about 3 times the air volume coming out of the vents and it is cold.

I'm excited to test the air conditioner in a couple of weeks on our trip to some hot locations. Thank you pnichols.

That’s awesome news. I’m going to do the same when it’s not 117 out.
Durb
Explorer
Jul 24, 2017
rvexodus wrote:
Durb wrote:
pnichols wrote:
The OP's air conditioining may not be operating as a "closed system" ... in that the A/C's air intake is not 100% circulating only air from the house interior. In other words some of the A/C's intake air is continuously made up of some new (hot) outside air that is leaking in. This means that there is an "outside air leak" somewhere in the A/C's intake system.

If the OP's A/C system is otherwise operating properly with no intake air leaks and with all windows/vents closed and is 100% using "recirculated intake air" like it's supposed to be, then it's outlet air into the interior is always around 20 degrees lower than it's intake air. Since the intake air is supposed to be 100% coming from the interior of the house, it's outlet air temperature is always getting colder and colder until limited by the thermistat setting ... THAT IS IF the BTU capacity of the A/C system is great enough to, at any expected outside temperature, swamp out the continual heat gain from the outside through the ceiling, the walls, and the floors.

One should always buy a new RV with the maximum BTU size air conditioning system(s) offered - just in case they find themselves having to camp in unexpectedly high temperatures. IMHO, that's part of the "self-containment" goal of an RV.

BTW, a leak in the intake system would also explain why opening some windows would help with cooling from an air-leaking system. The slight pressure increase in the interior - as maintained by the air conditioning system's fan(s) trying to pull in some air from the outside, when they shouldn't be - would be relieved by the open window(s)r - thus permitting flow of some extra cooled air from the leak on out the open window(s).

I Have the same problem with my Carrier air conditioner. The best it could do was lower the trailer to 88 when 92 outside. This post inspired me to get on the roof and pull off the cover and shroud. I had a spot where the coper tubing enters the plenum where hot air could come in but it was minor and I fixed it with some foam tape.

I did notice there was a large opening between the intake and output sides within the air conditioner house portion. The installer stuck a piece of foam in front of the gap and not sealing it. The fan was just circulating air within the unit not pulling it over the cooling coils and not pushing it out the vents. I sealed the gap thoroughly. Turned it on and I now have about 3 times the air volume coming out of the vents and it is cold.

I'm excited to test the air conditioner in a couple of weeks on our trip to some hot locations. Thank you pnichols.

That’s awesome news. I’m going to do the same when it’s not 117 out.

As a follow up I just returned from our trip. Outside air was 101 degrees, inside 81 degrees. 20 degree drop, I'll take it. This air conditioner tune up could have been completed from inside the trailer.
rvexodus
Explorer
Jul 24, 2017
Durb wrote:
rvexodus wrote:
Durb wrote:
pnichols wrote:
The OP's air conditioining may not be operating as a "closed system" ... in that the A/C's air intake is not 100% circulating only air from the house interior. In other words some of the A/C's intake air is continuously made up of some new (hot) outside air that is leaking in. This means that there is an "outside air leak" somewhere in the A/C's intake system.

If the OP's A/C system is otherwise operating properly with no intake air leaks and with all windows/vents closed and is 100% using "recirculated intake air" like it's supposed to be, then it's outlet air into the interior is always around 20 degrees lower than it's intake air. Since the intake air is supposed to be 100% coming from the interior of the house, it's outlet air temperature is always getting colder and colder until limited by the thermistat setting ... THAT IS IF the BTU capacity of the A/C system is great enough to, at any expected outside temperature, swamp out the continual heat gain from the outside through the ceiling, the walls, and the floors.

One should always buy a new RV with the maximum BTU size air conditioning system(s) offered - just in case they find themselves having to camp in unexpectedly high temperatures. IMHO, that's part of the "self-containment" goal of an RV.

BTW, a leak in the intake system would also explain why opening some windows would help with cooling from an air-leaking system. The slight pressure increase in the interior - as maintained by the air conditioning system's fan(s) trying to pull in some air from the outside, when they shouldn't be - would be relieved by the open window(s)r - thus permitting flow of some extra cooled air from the leak on out the open window(s).

I Have the same problem with my Carrier air conditioner. The best it could do was lower the trailer to 88 when 92 outside. This post inspired me to get on the roof and pull off the cover and shroud. I had a spot where the coper tubing enters the plenum where hot air could come in but it was minor and I fixed it with some foam tape.

I did notice there was a large opening between the intake and output sides within the air conditioner house portion. The installer stuck a piece of foam in front of the gap and not sealing it. The fan was just circulating air within the unit not pulling it over the cooling coils and not pushing it out the vents. I sealed the gap thoroughly. Turned it on and I now have about 3 times the air volume coming out of the vents and it is cold.

I'm excited to test the air conditioner in a couple of weeks on our trip to some hot locations. Thank you pnichols.

That’s awesome news. I’m going to do the same when it’s not 117 out.

As a follow up I just returned from our trip. Outside air was 101 degrees, inside 81 degrees. 20 degree drop, I'll take it. This air conditioner tune up could have been completed from inside the trailer.

Awesome and congrats. There is hope for me yet!
BarneyS
Explorer III
Jul 24, 2017
As Durb has mentioned, it sounds to me like you may have an inside the air conditioner leak. There is a divider (usually stiff foam) that separates the "warm" or intake side of the air conditioner with the "cold" or output side. If that divider has slipped out of place or was not installed correctly you could have some of that cold air being forced out the exhaust of the intake instead of into the trailers air conditioning ducts.

Also, the ducts themselves, where they attach to the air conditioner, may not be sealed up correctly and you are loosing cold air to the space between the roof and the inside ceiling covering.

Maybe not but would sure be worth checking. Need to drop the inside cover and bottom plate to see.
Barney
rvexodus
Explorer
Jul 24, 2017
BarneyS wrote:
As Durb has mentioned, it sounds to me like you may have an inside the air conditioner leak. There is a divider (usually stiff foam) that separates the "warm" or intake side of the air conditioner with the "cold" or output side. If that divider has slipped out of place or was not installed correctly you could have some of that cold air being forced out the exhaust of the intake instead of into the trailers air conditioning ducts.

Also, the ducts themselves, where they attach to the air conditioner, may not be sealed up correctly and you are loosing cold air to the space between the roof and the inside ceiling covering.

Maybe not but would sure be worth checking. Need to drop the inside cover and bottom plate to see.
Barney

Thanks Barney. Only my garage has the ceiling cover. The main AC and the bedroom AC have no inside portion. Sounds like I will need to pull the covers off the unit on the outside and possibly pull up the unit. Will have to wait until we have sub 100 deg days. For now, I’m limping along :)

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