Technician arrived on site and started performing combo tuneup on one HVAC system. Filter was completely restricted. And blower and electrical cabinet was dusty. Cleaned out the compartments. Ignition components were okay. Flame sensor and igniter are good. Blower cap is failing. Blower is over amping. Return is was to small and the static reflects that at .8 Unit tripped on high limit while service was going. Even without the filter. Blower wheel is caked with dirt. Temp split is over the rated amount. Recommend replacing unit as it’s failing. Went to the condenser and cleaned the coils. Once cleaned started checking the electrical. Data plate was faded and couldn’t pull ratings off. Compressor on start up was drawing high amps even with the hard start. Refrigerant charge is low. Suction line is icing up. Customer declined all recommendations at this time. Will possibly schedule repairs if the home inspector dings his unit.