I noticed poor idle in my 96 GT when AC is on! Idle is ~800 rpm for 10sec. and then it jumps. into ~1200 for a 0,1 sec. and again runs nicely about 10 sec. and jumps again to ~1200 rpm for a 0,1 sec.! When AC is not in use (OFF or in VENT position), car runs idle like it should! I bought new IAC-motor and it made no difference! There is no leaks in intake before TB (K&N CAI installed, and all hoses are tight). DO you guys have any suggestion what might be wrong in my car?
AC causing poor idle?
- Thread starter mikkok
- Start date
Willis_98GT
Well-Known Member
its computer controlled to raise idle to compensate for the increased belt accessory load.
im not sure exactly what your referencing being wrong with your car?
im not sure exactly what your referencing being wrong with your car?
DropTopPony
Post Whore
Mine will fluctuate some when the AC is on but not as much as you are describing.
everytime the a/c cycles the idle will go up for a second, then back down.
the problem is the IAC duty cycle has to go up (iac opens further) when the a/c clutch is engaged. when the a/c clutch disengages the iac duty cycle has to go down (iac closes a little), this cant happen fast enough to keep a rock solid idle, so it jumps a bit..... nothing to be worried about, if this didnt happen the car would stall if the steering was turned or the a/c kicked off as the car was coming to a stop....
the problem is the IAC duty cycle has to go up (iac opens further) when the a/c clutch is engaged. when the a/c clutch disengages the iac duty cycle has to go down (iac closes a little), this cant happen fast enough to keep a rock solid idle, so it jumps a bit..... nothing to be worried about, if this didnt happen the car would stall if the steering was turned or the a/c kicked off as the car was coming to a stop....
JerZeyStangz
Well-Known Member
Weak alternator can make the frequency of the jumping idle crazier. I would just reset the computer by pulling the battery to see if it makes a difference, but overall its normal, mine does this as well but not a crazy.
greenscobie86
Well-Known Member
My car does this. It also likes to stick on higher RPMS sometimes when the A/C is on...
I just kinda deal with it as all my other mustangs did this as well...
I just kinda deal with it as all my other mustangs did this as well...
