In the Seattle climate, a functioning economizer is the difference between manageable energy bills and a facility disaster. When an RTU (Rooftop Unit) fails to provide “free cooling,” we don’t just replace the damper motor. As an AC/C TECH HVAC/R Certified technician, I trace the logic from the enthalpy sensor to the controller.
The Economizer Sequence of Operation
The logic controller compares the outdoor air temperature/humidity against the return air. If the conditions are met, the controller bypasses the compressor and opens the outdoor air dampers. If the dampers stay closed, we test the 24V actuator motor and the enthalpy sensor for a signal. In the salt-air environments of the Sound, sensor corrosion is the #1 cause of logic failure, leading to unnecessary compressor wear.
Why is my rooftop unit blowing warm air during a cool Seattle morning?
This typically indicates the economizer dampers are stuck closed or the outdoor air sensor is sending a faulty “High Heat” signal to the controller. We verify the sensor’s Ohms against the manufacturer’s temperature chart to ensure the logic board is receiving the correct data.
Need Precision Rooftop Service?
We specialize in complex RTU diagnostics and economizer calibration for commercial properties.
- Call: (425) 535-8990
- Service: Same-Day Rooftop Unit Repair Seattle