A missed opportunity for evidence-based scientific inquiry?

In listening to Tom & Ray’s advice to Kurt whose Crown Vic was ‘losing its cool’, I wondered if there would be any benefit to applying the solutions serially, as opposed to dumping them both in at the same time? This way, he could know which intervention made a difference, and so discover if there is, in fact, a slow leak in the A/C system and so plan his future maintenance/repairs with the benefit of this information? Or do I have an undiscovered leak somewhere?!