Why does my heater blows warm air in the summer and cold air in winter?

30

Asked by GuruSBSQT Aug 06, 2020 at 03:50 AM about the 1987 Mercury Grand Marquis LS Sedan RWD

Question type: Maintenance & Repair

Heater blows warm air in the summer with controls set to off.  Heater blows cold air in winter  controls set to on.  Thermostat replaced, new radiator, new blower switch, new heater control valve. Any repair suggestions?

1 Answer

3,655

blend door issues, perhaps. Or worse, broken actuator ( interior ).

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