Running A/C on Low

[Dynalmadman]

Hi guys,

Wife and I are pretty new to RVing, just bought our 5th wheel a couple weeks ago and are loving it so far.

When we bought it, our salesman and the tech that gave us our walk thru instructed us to not run the A/C on lo fan because there was a greater chance of freezing up the unit. Lo was fine for heating but not cooling. A/C must be run on Hi.

Now we have 2 units, one in the main living area and another in the bedroom. They are pretty loud and wake us up every time it cycles on during sleep.

Finally, my question. Is this true? Are we risking a freeze up if we run the bedroom A/C on low? Didn't want to try it until I get some wisdom from you fine folks.

Thanks.
Michael

[TXiceman]

When you are running the fan on low speed, you are moving less air across the evaporator. Lees air means less heat exchanged and less refrigerant vapor generated in the evaporator. The compressor is a PD device (positive displacement) and will move the same volume of refrigerant with each stroke or cycle. The mass flow is lower but the specific volume changes so that there is sufficient volume of refrigerant for the compressor. This causes the temperature in the evaporator to drop and approach freezing. Once the evaporator coil is at freezing or lower, ice will start to form on the coil.

When operating properly an air conditioning unit should not have ice or frost on the evaporator. If you are getting frost or ice, something is not right and the first thing to check is low air flow.

Ken

[wa8yxm]

Dynalmadman wrote:
Now we have 2 units, one in the main living area and another in the bedroom. They are pretty loud and wake us up every time it cycles on during sleep.

Try an expierment... I think you will be surprised.

Sounds like your fan has 3 settings, HIGH/LOW/AUTO and you have it on AUTO so it cycles on and off... Put it on HIGH, lock it on so the fan runs 24x7 and see how quickly you learn to ignore it (Five minutes tops)

I only notice mine if the breaker trips.

[tvman44]

I run our BR A/C on low at night, no problems in the last 6 years. 🙂

[Nolan]

I heard the same story of running the fan on the A/C on high when we got our trailer 10 years ago. I don't know if it is true or not but have always ran it on high. The bedroom A/C was put in at a later date and the fan runs all the time. The A/C compressor kicks in when needed. I run that one on low. We have just run the fan on the unit in the bedroom when the neighbors are noisy when we want to sleep.

[eHoefler]

Run them on high until you get the temperature stabilized ( cycling ) at your setting, usually the first day for us. If you don't open up the camper and leave it closed up, you can run it on low once the humidity has been reduced inside. I have never been froze up, running the A/C this way.

[Gale_Hawkins]

Yes but we tend to run the front one in the evening. You will know if it freezes up then you can leave it off for a while and run Hi only. We leave the blower blow all the time so the noise of start up is not huge but I sleep when I sleep. 🙂

[Golden_HVAC]

Hi,

IF the air conditioner is running so long that they rarely cycle off, such as a average RV with only 1 A/C unit, and they run 23 hours out of 24, then it can freeze on low speed, and normally will not freeze on high speed.

Yet you have 2 A/C units in a reasonably small RV, so the compressors normally will cycle off for about 10 or more minutes per hour, and will offer time for any frost to get off the coils. Yes in your case, running on low fan will help it be quiet, and will not freeze the coil in normal weather.

However in high humidity, it can still freeze up. If you leave the fan "On" then it will not cycle off and wake you when it restarts, and also it will thaw out any ice that might get on the coils during the compressor off time.

Some say they will run the bedroom A/C on high speed while in the living area, and then the living area A/C on high while sleeping, and that keeps the noise "Over there".

Good luck!

Fred.