Community Forums

lenny-shawna · 07-08-2018, 07:03 PM

Hello All,
We are having issues with our AC mainly at night and want to know how you guys set the temp. I have three 15K AC units on the roof. The temp in the RV is set around 73, during the hot and humid FL summer day they work great, temp stays at 73, no problems.

At night however, it's hard to sleep because it's too hot or too humid, regardless, we wake up every night hot. I tried a few different things. I set the temp to 71 on all three units, same result, it gets real cold then hot in the middle of the night.

Last night I turned the middle AC unit off and set the other two to 72, same thing, too hot or too humid. I believe it's the latter.

My thinking is the coach is insulated well therefore the three AC units are too much, the coach cools too quickly and by not running long enough the humidity rises. Again, I am speculating on the humidity issue as I did not actually check to see what the level is.

What should I do, should I turn off two of the AC units or turn the front up to 76, the middle off and the bedroom down to 72?

Thanks,

docj · 07-08-2018, 07:09 PM

That's why when we're in a very humid area, such as south TX, we use a free-standing dehumidifier in the MH. You essentially have too much cooling capacity and it doesn't run enough to keep the humidity down. If it ran more you would freeze. You probably would do better at night turning off one of the units.

This is a common A/C design issue in residential and commercial systems. It might seem like a good idea to have as much cooling capacity as possible, but it's not. If you have too much you end up with a moist, cold cave!

Podivin · 07-08-2018, 07:16 PM

Is the fan speed set to high or low?
If it's on low it's possible that the rooftop units are freezing up which will prevent proper cooling.

When you wake up 'too hot or too humid' do you check the thermostat to see what the actual temp in the RV is? If it's at the set temp then the ACs are working, if it's too hot then they are not.

What we do at night is to turn the bedroom AC to the proper sleeping temp for us, and turn the front AC 'off' but set the fan to 'On' so that the fan runs all night though it never tries to cool. (we only have 2 AC, not 3 like you do). That makes the bedroom nice and cool and also keeps air moving in the rest of the RV.

lenny-shawna · 07-08-2018, 07:17 PM

Quote:

Originally Posted by docj

That's why when we're in a very humid area, such as south TX, we use a free-standing dehumidifier in the MH. You essentially have too much cooling capacity and it doesn't run enough to keep the humidity down. If it ran more you would freeze. You probably would do better at night turning off one of the units.

This is a common A/C design issue in residential and commercial systems. It might seem like a good idea to have as much cooling capacity as possible, but it's not. If you have too much you end up with a moist, cold cave!

Hi Joel,
That's what I was thinking so I turned off the middle AC and it didn't help. Should I turn off two units and if so which two? I'm thinking on leaving the middle one on and turning the front and the bedroom off.

bluepill · 07-08-2018, 07:20 PM

What Doc said. The optimum operation for dehumidification is having your A/C running almost all the time to maximize the amount of water removed.

Try the one only, maybe with a portable fan to help distribute the air through the entire coach.

lenny-shawna · 07-08-2018, 07:20 PM

Quote:

Originally Posted by Podivin

Is the fan speed set to high or low?
If it's on low it's possible that the rooftop units are freezing up which will prevent proper cooling.

When you wake up 'too hot or too humid' do you check the thermostat to see what the actual temp in the RV is? If it's at the set temp then the ACs are working, if it's too hot then they are not.

What we do at night is to turn the bedroom AC to the proper sleeping temp for us, and turn the front AC 'off' but set the fan to 'On' so that the fan runs all night though it never tries to cool. (we only have 2 AC, not 3 like you do). That makes the bedroom nice and cool and also keeps air moving in the rest of the RV.

The fan speeds are set to "auto" and no, I did not walk to the front to check the actual temperature even-though I should have.

I'm thinking about buying one of those digital temp/humidity readers if this keeps up.

lenny-shawna · 07-08-2018, 07:22 PM

Quote:

Originally Posted by bluepill

What Doc said. The optimum operation for dehumidification is having your A/C running almost all the time to maximize the amount of water removed.

Try the one only, maybe with a portable fan to help distribute the air through the entire coach.

I will try leaving only the middle unit on with a fan.
Thanks

PaulTNaples · 07-08-2018, 07:54 PM

You said you had the thermostat set to auto. Try setting it to cool only. When I set to auto and the temp dropped it would then switch to heat to bring the temp up to the setting.

lenny-shawna · 07-09-2018, 03:37 AM

Quote:

Originally Posted by PaulTNaples

You said you had the thermostat set to auto. Try setting it to cool only. When I set to auto and the temp dropped it would then switch to heat to bring the temp up to the setting.

The unit is set to cool and the fan is set to auto

GKU · 07-09-2018, 04:58 AM

There are two things that you can try. Set the unit fan to ON instead of AUTO, this will keep the AC fan running all the time. OR you can buy a small fan put it on the dresser top across from the bed, this keeps the air moving and you will hear the AC cycling more. This the the method we use and it works great.
Here's a link to the fan we use. FAN

docj · 07-09-2018, 07:21 AM

Quote:

Originally Posted by lenny-shawna

Hi Joel,
That's what I was thinking so I turned off the middle AC and it didn't help. Should I turn off two units and if so which two? I'm thinking on leaving the middle one on and turning the front and the bedroom off.

Sure, if the cooling load isn't that high and one A/C can handle it then it will "work harder" and longer so it has more time to remove water vapor and lower the humidity. Try putting the other A/C's in the "FAN ON" status even if the compressors are off just so the air moves around and keeps the MH comfortable.