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  • 1996 - 2004 SN95 Mustang -General/Talk-
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rough ide, surge with AC on?

  • Thread starter Thread starter jpbaker22
  • Start date Start date May 6, 2004
J

jpbaker22

Founding Member
Jan 27, 1999
185
0
0
Missouri
May 6, 2004
#1
  • May 6, 2004
  • #1
i have a dilema.
put on some underdrive pulleys about a month ago.
i did notice afterwards a bit of a rough idel. not too bad.
It is not my daily driver, so i don't recall using the AC/defrost until recently. Whenever i turn on the defrost/ac the motor surges every 2 seconds to about 1000 rpms (almost like the car has a heart beat. IT'S ALIVE!! IT"S ALIVE!!) I'm not sure if this has to do with the pullies or the fact that i cleaned the engine with degreeser and water around the same time. It even surges with the same rythem at highway speeds when i'm not accelerating. What could it be?
has about 56k miles

I have k&n filter, high flow x w/cats and straight through exhaust and pulleys. Is it about time for a chip? would that fix it?
 
J

jpbaker22

Founding Member
Jan 27, 1999
185
0
0
Missouri
May 11, 2004
#2
  • May 11, 2004
  • #2
still no ideas?
I looked around under the hood the other day and nothing seems to be obviously wrong.
no strange noises,all electric connnectors are tights, fluids ok.
do i need to reset the computer maybe after the pulley install?
 
M

MMARTIN 6

New Member
Jun 4, 2003
19
0
0
May 12, 2004
#3
  • May 12, 2004
  • #3
jpbaker22 said:
still no ideas?
I looked around under the hood the other day and nothing seems to be obviously wrong.
no strange noises,all electric connnectors are tights, fluids ok.
do i need to reset the computer maybe after the pulley install?
Click to expand...

Sounds like you need a tune.
 
C

Cobra01Vert

New Member
Apr 23, 2004
39
0
0
May 12, 2004
#4
  • May 12, 2004
  • #4
sounds like the AC is bringing down the base idle and then the comp compensates by opening the throttle like when you let the clutch and bog and then push it back in without touching the throttle.
I know on the older cars there was a setting to increase the idle when the AC is on, could be that whatever raises the idle when the AC is on is not working, sorry if this isn't much help.

Low idle would also make the car idle rough, try unplugging the batt and if that doesn't work then have the base idle reset
 
J

jpbaker22

Founding Member
Jan 27, 1999
185
0
0
Missouri
May 13, 2004
#5
  • May 13, 2004
  • #5
I tried unpluging the Batt last night. no luck.
If I put my ear to the air box (silencer removed) with the AC on. I can hear it make a *fwop* sound right before it surges. almost sounds like something is opening and closing quickly. Anyone have any info on adjusting the idle without an aftermarket chip?
Also, what is that 3 pronged wheel on front of the AC compressor pulley? it can move independant of the pulley it self. It actully spun about a quater turn clockwise last night while I was peaking around under the hood.



BTW. Ordered the Maximum Motorsports suspension starter kit yesterday. should have it installed by next weekend!
 
J

jpbaker22

Founding Member
Jan 27, 1999
185
0
0
Missouri
May 16, 2004
#6
  • May 16, 2004
  • #6
The saga continues.
OK. I've made some diag. progress.
the AC compressor actuall isn't turning with the ac on. it'll spin a little bit sporadically but that's it. that would explain why the defrost and the AC blow warm air.
Now if I pull the "sensor" connector from the AC tank in the passenger side corner of the engine compartment it stops surging. I shorted out and the connector and the comperssor started turning, ice cold air came out of the vents, and the surge quit. (and the fan came on). as soon as i plugged in back in it did the same surge again.
Any ideas on what i should do next?

 
C

Cobra01Vert

New Member
Apr 23, 2004
39
0
0
May 16, 2004
#7
  • May 16, 2004
  • #7
could be the low or high pressure sensor, which means you are low on freon or the switch is junk. Had a car that needed a new sensor for one or the other a few years ago and cost like $90 to have fixed, well worth getting it fixed,

Get a chiltons and find out what it is or go to an AC shop for an estimate
 

marcus95

Active Member
Jan 26, 2004
2,133
0
46
California
May 16, 2004
#8
  • May 16, 2004
  • #8
Cobra01vert is probably correct. When your compressor wants to kick on and off with your AC in the on position inside the car it means that your are low or out of freon or whatever your AC system is using.
Go get a charge and see if it fixes your problem
Your MM upgrade will kick A**. You will love it.
 
J

jpbaker22

Founding Member
Jan 27, 1999
185
0
0
Missouri
May 20, 2004
#9
  • May 20, 2004
  • #9
FIxed!
Had the shop fix the AC issue while i had my MM kit put on.
They sad it was a Compressor initiator switch (or somehting like that). Freon level was fine. Runs like a champ now and blows ice cold.

oh... and the MM starter kit kicks @$$! ride quality is very similar to stock except for the big bumps.
So far it lowered a little over an inch on all corners. It was only done yesterday so i expect it to drop a tad bit, but it looks great. Oh and the on and off ramps seem like straight lines.

too bad the rotors block the pretty red springs and yellow and blue shocks!
 
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