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TOO COLD....

How to avoid a freeze up inside the ac unit. This photo was sent by a customer in Florida who woke up to a frozen ac unit. Thankfully he let us know right away so we could start investigating....


If you look closly at the photo not only are the cooling coils frozen solid but the plastic base-pan surrounding the coils are also frozen. Its rather impressive considering its a large area and this was accomplished by a 12v compressor as long as its not your rig.



We spent a solid day trying to duplicate the conditions that caused the big freeze in our Phoenix warehouse with no success. We could not get the ambient temperature low enough nor the humidity high enough to duplicate the conditions in Florida.


We knew the air conditioner ran all night at the lowest temperature setting (59F 15C) with the lowest fan setting (1). We had a hypothesis that the low settings in conjunction with the lower nighttime temperature was the issue unfortunately duplicating exactly in Phoenix in the summer was proving to be a challenge.


Even with the fan on low (1) we could not duplicate the big freeze. But, we were not detoured. After disconnecting the fan compleatly from the control panel the cooling coils quickly froze. The cooling coils generally run at or right above freezing but the fan quickle pushes the warm air through the coils. The transfer of warm air through the coils keeps the coils from freezing. Without sufficient air volume passing through the cooling coils the ac unit will freeze solid over time. With no fan the cooling coils will freeze within minutes.


DO NOT SET THE UNIT TO THE LOWEST AVAILABLE TEMPERATURE WITH LOW FAN.


It's a powerful compressor for 12V.


What have we learned, and how to use this information in our everyday lives?


When using your ac unit in moderate temperatures use the thermostat on the control panel to pick a desired internal temperature that will allow the compresser to turn on and off regularly throughout the duty cycle.


Here is a good example. At night set the temperature on the unit to 75F 24C with low to mid fan on. This will allow the the coach to cool down to the desired temperature. Once the desired temperature is reached the compresser will turn off making sure the coils do not freeze.


If you set the temperature to 59F or 15C the van may never reach this low of a temperature inside causing the compresser to stay on all night without turning off. If you set the internal temperature to 59F or 15C make sure to increase the fan speed to make sure to avoide the big freeze.


DO NOT SET THE UNIT TO THE LOWEST AVAILABLE TEMPERATURE WITH LOW FAN.



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