How does accumulated dirt on the condenser coil affect system operation?

• A. Lowers the condenser pressure and temperature
• B. Raises the condenser pressure and temperature
• C. Has no effect on system operation
• D. Improves overall efficiency

Answer: (B)

Dirt on the condenser coil reduces heat transfer from the refrigerant to the surrounding air. The condenser’s job is to reject heat so the refrigerant can condense. When airflow is blocked by dirt, less heat is removed, so the refrigerant leaves the condenser at a higher temperature and higher pressure. That means the high-side pressure and condenser temperature both rise, which makes the system work harder, lowers efficiency, and can trigger safety limits. So the effect is an increase in condenser pressure and temperature, not a decrease, no effect, or an improvement in efficiency.