CSLB C-20 HVAC ContractorCooling and RefrigerationMedium
On a residential split system equipped with a thermostatic expansion valve (TXV), where is the filter drier normally installed?
- AIn the suction line, between the evaporator and the compressor
- BIn the discharge line, between the compressor and the condenser
- CIn the liquid line, between the condenser outlet and the metering device
- DInside the suction line accumulator housing
Show answer & explanationAnswer & explanation
Correct answer: C. In the liquid line, between the condenser outlet and the metering device
The filter drier is installed in the liquid line so it can remove moisture, acid, and debris from the liquid refrigerant before it reaches the fine metering orifice of the TXV, protecting it from clogging and preventing moisture-related acid formation.
Why the other options are wrong
- A. Suction line filter driers exist for burnout cleanup but are not the standard location for routine systems.
- B. Discharge line filters are not standard for moisture/debris removal in residential systems.
- D. The accumulator does not house the filter drier.
Filter Drier Placement
The filter drier is installed in the liquid line ahead of the metering device to remove moisture, acid, and debris before refrigerant reaches the TXV or orifice.
- Protects TXV/orifice from clogging
- Removes moisture to prevent acid formation
- Should be replaced after compressor burnout (suction line drier used temporarily)
Memory trick: Clean the liquid before it meets the tiny valve.