At what outdoor temp does the unit stop heating. model lsn186he

As you may know, heat pumps will not work in extreme cold outdoor ambience temp. It is why the aux heat is there as a supplement.
7 blinks indicates a furnace roll out switch problem. Lack of airflow, lack of combustion exhaust flow, switch fatigue, clog on air filters. The roll out switch senses fire overheating the heat exchanger box and if the temp exceeds the switch (thermal switch) operating temp, then the switch activates and stops the fire and triggers the alarm.

I can not find a 38 anywhere. If I had to guess it would be a temp sensor. Be sure the filter is clean, pull the disconnect out at the outdoor unit for 10 seconds and reinstall. You may find the 38 on the underside of the top panel on the outdoor unit. Best Wishes!!

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since this question is very non specific i.e., no brand name, model or serial numbers, I can only assume that this is the type of unit that monitor the outdoor temp and does not require any settings. If you need more info, please include more details. Thanks.

Select hot mode except cool

I have experienced the same with numerous different, "quote un quote" atomic clocks! Please don't forget that this sender unit, that goes outside, generates a RF Singal to be received by the clock inside. This unit transmits a signal 433 MHz signal approximately every. 3 minutes, and after so many years the sender unit's RF section(electronics) just goes out or no longer function properly or not at all! The transmitter/sender for this model number, according to "3M" is obsolete and can no longer be furnished, DRATTS !!!!!

sounds like you have a bad coppressor

I would start with your outdoor thermostat located in
the unit outside. I`m assuming this is a heat pump.
When the outdoor temthermostat is set to say 40F
anything lower than that and you are not using the
compressor, you are using electric heat thats located
in the air handler unit in the house.

I`m also assuming this is a split system and not a
packaged unit. If you are mechanically inclined and
you can locate the outdoor thermostat lower it below
the outdoor air temp and see if the unit comes on.

Sounds like you might have a problem with your electric heat or emergency heat

Get the charge tested, check the sub-cooling across the outdoor coil.

20kw heat should have 2 separate 60 amp circuits on number 6 wire.

If the outside temp. is lower than 32 deg. F it is normal for the outdoor unit to build up ice but not safe for the motor compressor. Because the safe outdoor temp. in heating is 5 to 64 deg. F but don't worry it has safety device to stop the operation.