Delta T, temp split, temperature difference. Why is it important? It’s a quick simple check to tell us what the unit could be doing.
• Normal range:
• Cooling mode → 18°F–22°F
• Heating mode (gas furnace) → 35°F–70°F depending on system design
• If it’s too low, the system isn’t removing enough heat = low charge, poor airflow, dirty coil/filter, bad blower, or oversized system.
• If it’s too high, airflow is too low or refrigerant charge is off — coil might be freezing or compressor overheating.
