AC unit freezing up.
This is our third weekend using our ac and the other two times it worked great. This time the unit has frozen up twice. We like it cold the first time the ac was on 60 and today it froze up when it wa...
Forum Discussion
rockhillmanor wrote:
3. Keep the fan on 'low' during really hot days. It can freeze up on those extreme hot days with fan on high.
4. You can add a small portable DE-humidifier to assist your AC. Adding this made a BIG BIG difference in my MH on those 95+ days.
RV'ing in the South was a big learning curve for me after years of trouble free RV'ing in the Midwest.
Some of this goes against basic A/C theory and psychometrics.
#3...Low speed is where you get into trouble and freeze the coil (ice it over). Keep the fan on high and the filters clean. also check for air leaks between the inlet and outlet of the unit.
#4...running the dehumidifier will add additional sensible heat load to the space and make the unit work harder against the additional sensible load. The dehumidifier will remove some of the latent load or moisture, but is adding sensible load
South and North...The northern part of the country typically has a lower humidity level than in the south. The load on a A/C unit consist of two parts, sensible cooling and latent cooling. The sensible part is the small part of the load and is basically show as a lowering of the ambient temperature. The latent heat is the larger part of the load and is the condensing the water vapor (humidity) from the air or lowering the dew point of the air.
With a RV A/C unit, I have found the least likely cause of a problem is "Low Freon" as these are hermetically sealed units. Most of the problems come from reduced air flow due to plugged filter or evaporator coil, bypassing air or fan on low or a displaced freeze sensor on the coil.
To check an RV unit, start the unit, set the t'stat lower to keep the unit running, fan on high speed and let it run for about 10 minutes before checking temperatures. Now get an air temperature with an accurate thermometer (not an infra red gun) of the air entering the unit and leaving the unit as close to the evaporator coil as possible. The leaving air should be 18 to 20 degF lower than the entering air temperature. More or less than this, you may have a problems.
Next note, the "humidity" or water vapor should NEVER freeze at the coil for a properly working unit. The coil should be running above freezing in an a/c unit. In a freezer application, a coil operating below freezing is normal and the coil and unit is designed to defrost the coil at intervals.
Ken
