Filter, airflow, capacitor, charge, ducts: the sequence that finds the cause without buying parts on guesses.
Diagnosis, repairs, and full systems in published ranges, and the repair versus replace arithmetic.
What clicks, what glows, what proves flame, and the safety lines that come before any repair.
The 5,000 rule, refrigerant reality, and the duct question that changes replacement quotes.
Same age, different odometer: a San Marcos system cools through long inland summers while coastal systems rest. How duty hours change the repair or replace math.