a2lahrairboardsbranamanbrazingcapacitorchargingcleaningcomponentscompressorcraigdiagnosisdiscussingductefficiencyelectricalfieldfurnacefurnacesgasheathvachvacrissuesleaksmethodsproblemsproceduresquestionsrecoveryrefrigerantrefrigerantssafetysubcoolingsystemtechniciantechnicianstipstoolstroubleshootingtyvacuumwithin