Repair, Replacement, and Service Procedures
This domain tests execution: correct disassembly, sealed-system work, and post-repair verification. Questions often ask for the next step in a sequence or the reason for a procedure.
General repair practice
- Follow the manufacturer's disassembly order; label connectors and photograph assemblies before removal.
- Use the specified fasteners, torque, threadlocker, and sealants. Over-torquing plastic and aluminum parts causes cracks and leaks.
- Replace gaskets, O-rings, seals, and filters as kits where specified; clean mating surfaces.
- Protect wiring from sharp edges and heat; route harnesses as originally installed.
Sealed-system repair
- Recover the charge into a certified cylinder; never vent.
- Purge with nitrogen while brazing to prevent internal oxidation.
- Replace the filter drier whenever the system is opened.
- Evacuate to 500 microns or below and perform a decay test; a rising vacuum indicates moisture or a leak.
- Charge by weight using the nameplate value; record the amount.
- Leak-test with an electronic detector or soap solution, then verify performance.
Mechanical and water repairs
- Belts: correct tension and alignment; replace matched sets.
- Bearings and motors: check shaft end-play, mounts, and cooling.
- Water systems: new hoses, clamps, and seals; check for cross-connections and backflow.
Post-repair verification
- Run a full cycle, check temperatures, pressures, current, and leaks.
- Confirm safeties and controls operate.
- Clean the work area and dispose of refrigerant, oil, and e-waste lawfully.
Worked example
A sealed-system compressor is mechanically seized. You recover the refrigerant, cut out the compressor, purge with nitrogen, and braze the new compressor and a new filter drier. You pressure-test with dry nitrogen, evacuate to 400 microns, and confirm the vacuum holds. You charge by weight to the nameplate, then verify suction and head pressures, superheat, and current against the data plate. You record the charge and leak-test the joints.
Traps
- Brazing without a nitrogen purge.
- Skipping the vacuum decay test.
- Overcharging "to be safe."
- Reusing a filter drier after the system has been open.