HVAC

BuildingWrench repair guide

HVAC

RTU Economizer Damper Stuck Open: Signs and Safe Checks

An economizer stuck open can make a building humid, hot, cold, or pressurized. Maintenance can compare commanded versus visible damper position and check for obvious mechanical obstruction.

Last reviewed 2026-09-12 · General facility-maintenance information, not a substitute for site procedures, manufacturer instructions, codes, or qualified professional judgment.

Routine facility fixSkill: Beginner-friendlyFormat: Diagnose → Fix → Test
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Safety boundary

Do not bypass safeties, open refrigerant circuits, or perform energized electrical diagnosis unless trained and authorized.

Full troubleshooting steps are in Pro

The safety boundary, quick answer and stop-work conditions above stay free. Pro opens the likely causes, symptom table, step-by-step procedure and preventive maintenance for this guide.

Stop and call a licensed professional when

  • Actuator wiring is required
  • Damper linkage is damaged
  • Access is unsafe
  • Humidity or pressure problem affects critical spaces

Mistakes, FAQ, parts and tools

Pro opens the rest of this guide: common mistakes, field FAQ, the parts list, and the tools for the job.

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Condensate Pump Not Working: Safe Checks Before Replacement

A condensate pump that stops moving water can shut down cooling or overflow. Check safe external power, the reservoir, float movement, and discharge tubing before replacing the pump.

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Rooftop Unit Not Cooling? Safe Checks Before Calling HVAC Service

When an RTU is not cooling, confirm that the building is actually calling for cooling before assuming a refrigeration failure. Check schedules, thermostat demand, filters, airflow, obvious alarms, and condensate safeties, then document what the unit is doing.

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HVAC Float Switch Tripped: What It Means and How to Reset It Safely

A tripped condensate float switch is a warning, not the root cause. The right fix is to correct the drainage problem, remove standing water, confirm the line drains, and allow the safety to reset naturally rather than bypassing it.

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RTU Fan Runs but No Cold Air: What Maintenance Should Check

If the rooftop fan runs but supply air is not cooling, the airflow circuit is alive but the cooling stage may be locked out, not commanded, or unable to operate. Gather evidence before calling service.