Trane XL 1400 question

[John D]

I recently purchased a house that has a 1994 Trane XL 1400 heat pump. It's been checked out and as far as I know everything is working properly.

My question concerns the secondary "thermostat" that is supposed to adjust the humidity in the home. Other than off, it has three settings- low, comfort, and high. I have a basic understanding of how A/C works from years in the auto trade but cant grasp how this would be accomplished. Does the unit have circuitry that adjusts the pressures based on the setting or have different blower speed/duration settings? Does it work at all?

Thanks is advance for any info

[thrugoodmarshall]

Normally, the blower runs high speed during the cooling cycle.

Where multiple speeds are supported (like your unit), the blower is typically run at a lower speed during dehumidification. Your unit supports multiple speeds during the cooling cycle, if the humidistat is installed. The secondary "thermostat", BAYSTAT253 is a humidistat, used for that purpose. Ref trane pub 22-1711-02-0102 (EN), p19, note 7 for wiring the humidistat.

Without a multi speed blower, a regular cooling cycle will still dehumidify.