Why???

[Origommi]

My 96 GT runs like a champ, BUTTTT when I turn on the AC or heater the car hiccups. By hiccups I mean it runs fine then bogs for a few seconds the runs fine again. This continues until I turn the AC off. Any ideas on why???? Thanks guys.

 

[maddogg545]

Well when you turn on the A\C your engine has to spin another pully and work twice as hard to cool the incoming air. That is why your car will seem "bogged" down a bit. I never hear this happining when you turn on the heat though.

 

[70stangcoupe]

I know the basics. When you turn your A/C on, the compressor turns on. It is belt driven, meaning it puts a greater drag on the motor.

In my 97 GT, the car skips for like half a second when I turn on either the heater or A/C, but after that, it's perfect again.

 

[Origommi]

Yes

I wish that was the only problem. It skips when both are running.

 

[mustang70]

I know on some cars the A/C compressor is turned on when you turn on the defroster. This is so the air hitting the windshield is dry and will clear it quicker.
The hiccup might be caused by the IAC motor. When you turn on the A/C it has to compensate for the extra load on the motor at idle. Your's might be a little slow. Maybe a cleaning or replacement is in order.