[scottz]

Originally Posted by scottz

I received this information from MicroAir tech support. I don't think they will mind me passing it on.

Dometic single zone systems suffer from a problem when operating cooling in automatic fan. The fan turns off with the compressor by design and this leads to frost formation on the coils. Eventually the coil temperature drops below 27° and the control board goes into freeze lockout. It remains there until the coil temperature rises above 55° where it will allow cooling again. Several users have reported they always ran the fan on continuous mode while cooling for that reason.



Older revisions of the 351 thermostat did not report this freeze lockout condition but the current version does. We are contemplating adding a software function to remedy this condition to bypass the lockout and run the fan if it occurs in a future update. For now, please be aware of this possibility and the solution. This is an inherent flaw in the control board logic and we will release a future update to compensate for it. Until then, make sure you are up to date and run the fan in low or high if freezing up occurs.

The only difference I have from this description is that, once they lock out, mine never start again. I have to turn them off then on to get them going again.