Before the repair
Describe the problem. Ask about the diagnostic charge, availability, and what authorization is needed before work begins. The technician should explain the finding and proposed repair in understandable terms.
After the repair
Request a service record, relevant test results, the installed part details, and written warranty terms. Ask which symptoms should prompt a follow-up.
Take this question into the conversation
“What did you find, what will the proposed work solve, and how will we know it worked?”
This is general educational guidance, not an assessment of your equipment. A qualified contractor must evaluate the actual system.