Composed of evaporator coils & refrigerant line.
Refrigerant passing through coils absorbs thermal energy from unconditioned air, resulting in cooler & drier air. This air is discharged into the living space.
- Input: Low-pressure, low-temp liquid/vapor-mix coolant.
- From: TXV
- Output: Low-pressure, low-temperator coolant vapor.
- To: Compressor
(It is labeled as "Metering Device" in the diagram above.)
The TXV can be thought of as a "microcontroller" for regulating coolant throughput over evaporator coils. It controls refrigerant volume by monitoring refrigerant temperature at the exit point for the evaporator via the sensing bulb. Higher refrigerant temp at the sensing bulb will allow in more coolant.
The TXV's sensing bulb is tiny sensor with isolated amount of coolant next to evap coil exit point. As temp of post-evap coolant increases & passes the configured threshold, the sensor coolant travels up the line and forces a diaphragm down. This diaphragm lowers the pin to let more coolant in (i.e. drops the pressure in the coolant line).
Source for much of this information is from this YouTube video.
- Input: High-pressure, medium temp liquid coolant.
- From: Condenser
- Output: Low-pressure, low-temp liquid/vapor-mix coolant.
- To: Evaporator
Blows ambient air over discharge line with condenser fan & coils.
- Input: High-temp, high-pressure coolant vapor from compressor
- From: Compressor
- Output: High-temp, medium-pressure liquid coolant.
- To: TXV
Increases pressure & temp of coolant vapor to operating values.
- Input: Low-temp, low-pressure vapor.
- From: Evaporator
- Output: High-temp, high-pressure coolant vapor.
- To: Condenser