Air conditioner freezing up question

[tex_wardfan]

My trailer has an airxcel 48000 series roof top unit. My question is have any of you, who have this unit, had any problems with the evaporator icing up? I did not need to use the unit on our first trip but I'm sure I will have to on the next. The guy who made our trailer ready and gave us the walk through said we should always run the unit at max cool to keep it from icing up. I read the owners manual for the unit and this doesn't seem correct. It seems like that would make it ice up. Any thoughts on this would be appreciated.

[tex_wardfan]

DutchmenSport wrote:
Only once did we have our air conditioner ice up. It was blowing nothing but hot air. It took a little to figure it out, that it iced up. I thought something serious was wrong. It wasn't.

I learned (and you can disagree with me, that's ok)... that in high heat and high humidity if the air conditioner runs for a very long time, the coils can ice up. The problem was resolved when I turned the thermostat to a higher temperature, thus allowing the compressor to cycle on-and-off. The ambient air around the air conditioner needed to help melt down the ice. Once the ice melted, it worked just fine.

That was the day I learned to initially set the air conditioner to a warmer setting, just low enough it kicks on. Once it reaches temperature, it will turn off (of course). Wait a couple minutes, then lower the temperature ever so slightly.

Once it reaches the new temperature, it will shut off again. Wait again and turn the thermostat down a pinch more again. Keep repeating.

If the compressor runs non-stop and is so cold the ambient air cannot actually .... (evaporate) ... it freezes up.

Of course, you REALLY only need to do this when the inside temperature of the camper is like .... a thousand degrees and the outside temperature is 2 thousand! (Ok, like closer to 95-100 and the outside temperature is not much cooler).

When temps are in the 70-80's and even low 90's, the air conditioner compressor will cycle on-and-off, giving the ambient air around it time to actually evaporate condensation and such.

The secret is to set the temperature so the compressor will cycle. Flipping it on with the thermostat as low as it will go and it's 100 degrees outside, and 120 inside, will never allow the compressor to cycle off-on. You CAN expect the coils and fins to ice up.

Ever since I started doing this, we never had ice build up again.

If the outside temperature is just too hot for the air conditioner compressor to cycle, and it runs constantly non-stop, they (may) ice up.

If it does, the solution is to simply turn the air off and let it thaw, then lower the thermostat slowly, little bits at a time.

Thanks, Dutchman. This was the kind of info I was looking for. Personal experience about how your perfectly good ac was freezing up and how you solved the problem. I was hoping to run the ac on low fan speed at night when trying to sleep because the higher speed is quite noisy. Do you always run yours on high fan speed? Even at night?

[newman_fulltime]

DownTheAvenue wrote:

Old-Biscuit wrote:
MAX COOL.....

Just means uses High Fan Speed vs Low Fan Speed

Low air flow
Dirty evap coil
Dirty return filter
High Humidity

All conditions that will cause a perfectly functioning A/C Unit to Ice Up

The #1 reason A/C units ice up is low on freon!

on a rv act he number one reason for icing up is dirty coils number two is a loose gasket

[newman_fulltime]

Old-Biscuit wrote:
MAX COOL.....

Just means uses High Fan Speed vs Low Fan Speed

Low air flow
Dirty evap coil
Dirty return filter
High Humidity

All conditions that will cause a perfectly functioning A/C Unit to Ice Up

Do not forget loose ac holes in intake hot air entering intake

[DutchmenSport]

Only once did we have our air conditioner ice up. It was blowing nothing but hot air. It took a little to figure it out, that it iced up. I thought something serious was wrong. It wasn't.

I learned (and you can disagree with me, that's ok)... that in high heat and high humidity if the air conditioner runs for a very long time, the coils can ice up. The problem was resolved when I turned the thermostat to a higher temperature, thus allowing the compressor to cycle on-and-off. The ambient air around the air conditioner needed to help melt down the ice. Once the ice melted, it worked just fine.

That was the day I learned to initially set the air conditioner to a warmer setting, just low enough it kicks on. Once it reaches temperature, it will turn off (of course). Wait a couple minutes, then lower the temperature ever so slightly.

Once it reaches the new temperature, it will shut off again. Wait again and turn the thermostat down a pinch more again. Keep repeating.

If the compressor runs non-stop and is so cold the ambient air cannot actually .... (evaporate) ... it freezes up.

Of course, you REALLY only need to do this when the inside temperature of the camper is like .... a thousand degrees and the outside temperature is 2 thousand! (Ok, like closer to 95-100 and the outside temperature is not much cooler).

When temps are in the 70-80's and even low 90's, the air conditioner compressor will cycle on-and-off, giving the ambient air around it time to actually evaporate condensation and such.

The secret is to set the temperature so the compressor will cycle. Flipping it on with the thermostat as low as it will go and it's 100 degrees outside, and 120 inside, will never allow the compressor to cycle off-on. You CAN expect the coils and fins to ice up.

Ever since I started doing this, we never had ice build up again.

If the outside temperature is just too hot for the air conditioner compressor to cycle, and it runs constantly non-stop, they (may) ice up.

If it does, the solution is to simply turn the air off and let it thaw, then lower the thermostat slowly, little bits at a time.

[Big_Katuna]

I run the fan on high not auto to blow air over the coils after the compressor cycles off.

This helps dry out the coils to reduce mildew.

And of course as stated, prevent icing.

[Old-Biscuit]

DownTheAvenue wrote:

Old-Biscuit wrote:
MAX COOL.....

Just means uses High Fan Speed vs Low Fan Speed

Low air flow
Dirty evap coil
Dirty return filter
High Humidity

All conditions that will cause a perfectly functioning A/C Unit to Ice Up

The #1 reason A/C units ice up is low on freon!

Let me point out something for you in my post


......cause a perfectly functioning A/C Unit to Ice Up


That and the fact that OP has a NEW RV.......isn't actually 'icing up'
but was questioning statement by RV Tech to use MAX COOL

Comprehension/reading


And YES low freon will cause icing up-------hardly a perfectly functioning unit

[fla-gypsy]

Old-Biscuit wrote:
MAX COOL.....

Just means uses High Fan Speed vs Low Fan Speed

Low air flow
Dirty evap coil
Dirty return filter
High Humidity

All conditions that will cause a perfectly functioning A/C Unit to Ice Up

X2, clean filter, coils and run fan on high. If that doesn't correct it seek professional help

[Alabama_Jim]

I had an icing up problem on a car ac and it was due to low Freon.

[DownTheAvenue]

Old-Biscuit wrote:
MAX COOL.....

Just means uses High Fan Speed vs Low Fan Speed

Low air flow
Dirty evap coil
Dirty return filter
High Humidity

All conditions that will cause a perfectly functioning A/C Unit to Ice Up

The #1 reason A/C units ice up is low on freon!

[Old-Biscuit]

MAX COOL.....

Just means uses High Fan Speed vs Low Fan Speed

Low air flow
Dirty evap coil
Dirty return filter
High Humidity

All conditions that will cause a perfectly functioning A/C Unit to Ice Up

[Gooding__R]

Have someone check the Freon.

[bsinmich]

The compressor runs at only one speed and gets the coils cold. Moving more air over them will keep the coils less likely to ice up. In high humidity this can be a problem but low humidity it may not be a problem on any setting.

[Clay_L]

It's counter intuitive but the tech was right.