Anti Cold Aire Feature -
As we approach the Winter time we begin to get a lot of calls for a very similar issue :
"When I run my unit in Cooling or Fan the indoor unit runs fine, But when I run my unit in Heating, there is no Fan at the indoor unit, What is going on?"
Mini splits for the most part have what is known as the Anti Cold Aire Feature,
This mode activates when Heating cycle is ran and keeps the indoor fan motor from running, while the outdoor unit builds up pressure and heat inside of the pipes.
Once the Pipe sensor at the indoor unit has detected it is hot enough it will allow the indoor fans to run.
How to Troubleshoot this with Customer -
1. How long has the unit been allowed to run? Many customer are unaware of the mode for the most part the initial Anti Cold run can leave the unit in that state for anywhere between 15-20 minutes. (25 minutes in a worse case scenario)
If this time frame has not even passed, have customer increase temp on unit and let the time frame pass.
2. If allotted time has passed, we look at the 2 things that can stop the unit from getting hot enough to run.
- Pressures - This one always comes first, it is important to confirm exactly what the state of pressure and refrigerant are.
Check Standing Pressure (Pressure when unit is off) And compare to chart.
- Pipe Sensor at the Indoor Unit - If the Pressures in unit check out we move over to the Indoor Pipe Sensor.
Most get to Sensor at the indoor unit's Main control board, from here unplug, and using NEEDLE NOSE Point adapters for the Multimeter, test the resistance coming from the sensor and compare to its respective chart.
Conclusion -
From either the time frame they are letting it run, the pressures, or the temperature sensor we should know where the issue is occurring. IF ALL CHECK OUT, recommend the replacement of the indoor MCB.