HVAC

BuildingWrench repair guide

HVAC

Thermostat Temperature Reading Is Wrong: How to Check It

A thermostat that reads several degrees off may be influenced by sunlight, wall temperature, drafts, local heat sources, remote-sensor configuration, or calibration. Verify with a good thermometer first.

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

  • Sensor replacement requires wiring
  • Bas configuration is unclear
  • Temperature control 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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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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Water-Source Heat Pump Not Cooling: Facilities Troubleshooting Checklist

For a water-source heat pump that runs but does not cool, verify thermostat demand, airflow, filter condition, loop-water availability, condensate safeties, and whether neighboring units are affected. Refrigerant and internal electrical diagnosis should be escalated.

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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.