awful bog in acceleration, help zx | Ford Escort Owners Association (FEOA)
Jumblium answered 5 years ago. Sounds like your idle air valve is not compensating for extra load from AC compressor be it a control issue or a physical problem with idle air valve it self. When you say heater do you mean defrost because AC generally works on defrost to dehumidify. Is the heater fan on when HVAC controls are turned on? Just double check that AC isn't turning on, open hood and watch compressor clutch.