What happens
Weather damage, loose clips or terminals add series resistance to the supply path.
Typical symptoms
Starts fail under load although unloaded voltage seems normal; discoloration or heat near a terminal.
Checks that distinguish this cause
Inspect the isolated assembly and evaluate localized voltage drop during an authorized live test. Examine both poles and fuse clips.
What can look similar
Pitted contactor poles or a loose whip connection can make the same symptom downstream.
Repair direction
Replace damaged approved disconnect parts and correct water entry or installation defects.
Verify the repair
Verify load voltage and reliable starts with no abnormal connection heating.
Equipment-specific limits
The line side can remain energized with the pullout removed. A non-fused disconnect has no fuse to test.
Practice this diagnosis
These simulated calls exercise this component or repair family. The article describes a broader diagnostic process; a call may represent a different cause within that family.
References and applicability
Original HVACSim explanations with manufacturer and instrument-maker references for further reading. These resources support the subject; their model-specific examples are not specifications for every system.
- Fluke: HVAC and industrial electrical testing applicationsElectrical measurement principles, including control-circuit voltage references.
- Fluke: HVAC multimeter troubleshooting guideIntroductory meter applications. Actual equipment ratings take precedence over generic examples.
Editorial review: 2026-09-29. Verify the current manual for the installed model.