Diagnostics & Theory
2026-05-24
📖 13 min read
Superheat — What It Is, Where to Measure It, and the Two Gauge Signatures That Diagnose Most AC Calls
Superheat is the single most-tested number on the HVAC license exam and the single most-misread number in the field. The fix is not memorizing one normal range — it is understanding what high or low SH actually proves about the system, paired with the other three numbers on your manifold. This is the conceptual + diagnostic entry point: what superheat is, where to read it, the 8-12 degree window, and the two gauge signatures every service tech should know cold.
superheat
subcooling
refrigeration cycle
TXV
piston