Weak Run Capacitor and Nonstop Blower Fix Steps Learn how weak run capacitors and failing fan motors can mimic a stuck fan relay or fan limit switch in HVAC systems, and get step by step tips to diagnose nonstop blower issues at home. We cover how to perform a safe power off spin test, spot delayed starts and humming, test capacitor microfarads with a multimeter, compare readings to label tolerance, and check motor windings for shorts or opens. Find out how a stuck thermostat fan call, dirty fil