Here's a little brief summary of how the cooling fan in your unit(s) work:
The Cel-Fi Network Unit (Window Unit) or Coverage Unit's internal cooling fan will automatically start only when the board temperature reaches 80 degree Celsius. If there are doubts whether the fan is functional, while looking through the vents and removing/restoring power, you’ll see the fan briefly spin at startup to indicate it's functionality. It's natural for your Cel-Fi system to feel warm to the touch, like any electronics your system will emit heat.The bottom of the Network Unit (Window Unit) or Coverage Unit will get warm, it’s anticipated, similar to the bottom of your cable box, DVD player, or radio tuner. The ‘touch’ temperature passes all regulatory safety tests and the product has been given the ‘UL’ safety mark. In the event the fan were to fail the Cel-FI system is designed to shut itself off if it gets too hot. Consequently, the Coverage Unit or Network Unit (Window Unit) will report an Error 3 or Error 4 respectively. Under the circumstances of an error message 3 or 4 please reach out to your point of sale or firstname.lastname@example.org.
Below you will find the location of the cooling fans for our specific Cel-Fi systems
Fan is inside both NU and CU
For RS225, RS224 ,RS218:
Fan is only in the NU
RS210, RS240, RS250,
No fans for Prime/GO
So why is there no cooling fans in some models?
Because there are cooling fins instead that provide convectional cooling from the free flow of air.