[RESOLVED] Idle Is Low When Ac Is On ( Solution)

[razey]

Hey guys,

I am having some trouble with my AC, i am not to sure what the problem is so any help is greatly appreciated. Basically, when i turn my AC on and put the car in drive, my RPM's drop to about 625 and slowly rise up to 700ish RPM's. Some times when i put it into drive the the AC on it stays at around 625 RPM's. It seems to be intermittent mabey...
Also i have a good size boost leak in the car, i dont think this will cause my AC problems, but i am fixing it this weekend.
Also my car was shipped to Puerto Rico about 2 months back, i ended up having to replace the Battery that died on the way over here. Could something be jacked up with my alternator or AC Compressor?

Thanks,
Steve

 

[the_mork]

Tuning the BISS isn't imperative so your mechanic didn't really screw up that bad.

Do a boost leak test, it is the only way to verify if you have a leak and how bad it is. You cannot tell just by what your gauge tells you.

I agree that your new ISC could be bad, I had three throttle bodies in my garage while I was trying to replace my intake manifold and throttle body, a 1g, 2g, and RVR throttle body. The ISC on both the 1g and 2g throttle bodies was shot. Only the RVR throttle body still had a good ISC



You will need to search for verification on this part but I believe that there is a procedure for setting the BISS without the use of a computer. Generally I would just use evoscan and adjust manually to a target RPM but you can also IIRC unplug the ISC and turn all of your accessories off (A/C mostly) then set your idle for 1500RPM. Like I said you will need to do some searching on this one, don't try it until you've had verification elsewhere because I don't remember the procedure with much clarity.

 

[RayBan GST]

hi all

well after so many hours of hard work i managed to fix my car , i changed the ISC and tuned the TPS according to the manual on this site


BISS screw is not 100% tuned but its ok now , the car idles at 700-800 when ac is on And stalls from time to time but acceptable


i fixed the leaks and now i am back to normal 14psi
but now i have one major problem my clutch is slipping ( DSM NEVER ENDING PROBLEMS)

i need to start now a new love story and change the clutch and search again and again for info i am going with EXEDY MBD081U ( i already made a Thread About that , i hope you will be able to help me )

thanks and 1000000000000000000000 thanks to STEVE for pointing the problems out.

 

[steve]

BISS screw is not 100% tuned but its ok now , the car idles at 700-800 when ac is on And stalls from time to time but acceptable

I'm glad that you seem to ok with this but to me it sounds like it's still not working correctly.
The car should idle around 750 RPM and be higher when the AC is on.

If the ISC was bad in the past it's possible that it damaged the drivers in the ECU.

Good luck with your clutch job.

 

[RayBan GST]

hi guys again ,


the problem is back and my idle is very low and the car is dying everytime i switch on the AC

i bought a new ISC motor again and installed again but still the problem is there ... i have searched everything done everyhting i can not find the problem


i removed the GAS in the AC compressor and put new gas again ( no overcharging at all) still my car is DYING , i can not drive it in this heat its 46 Degrees here with 74 Humidity its HELL


### guys again i need a BRAIN STORM on this problem , i have checked everything also new plugs new tension wires everything , even i tried new battery and altenator



thx

 

[zimfro]

A Steve said above, it is possible that the ECU has been damaged. Remove it and looked for some burnt chips.

 

[badabing33a]

who needs AC? . I would never use the AC on my dsm. I have the heater on in the summer just to be safe. But does idle drop when u use the heater, flip on the lights, etc. and not just the AC?

 

[steve]

who needs AC? . I would never use the AC on my dsm.

If you lived in Dubai you wouldn't be saying this.

 

[RayBan GST]

night joker / this place is not for joking , if you have something useful say it if not please DO NOT POST


Thanks

 

[roni-wan]

I´m having a similar problem, my a/c compressor was shot, after replacing it and charge again the car feels really really heavy with the a/c on. I feel like takes a lot of effort for the engine to move with the a/c

the vacuum drops to -20 to -15 it used to drop to around -17 when a/c was running fine a long ago and sometimes goes lower and also now its cycling on and off while driving.

tried everything and thinking the expansion valve its causing me this problems

 

[dsmtsi95]

One of my problems was the battery was low or bad.
Every time i turned the a/c on, it would idle real low.
I changed to a bigger battery and it stopped.
It was like a big current draw.

 

[RayBan GST]

i tried another battery another alternator but NO it did not fix the problem and speaking about the vaccum my vaccum drops to 12 and sometimes 14 when the AC is on

while the AC is on the car feels like a dog , the turbo will start spooling at 2000 RPM and sometime i can see 5 PSI of boost but no accelaration

my car runs and drives great without AC but here in Dubai you can not live nor drive your car without AC today its 46 degrees and humidity is 76% ( no need to tell you more about this damn weather)

guys again i really need your help in here

 

[roni-wan]

i tried another battery another alternator but NO it did not fix the problem and speaking about the vaccum my vaccum drops to 12 and sometimes 14 when the AC is on

while the AC is on the car feels like a dog , the turbo will start spooling at 2000 RPM and sometime i can see 5 PSI of boost but no accelaration

my car runs and drives great without AC but here in Dubai you can not live nor drive your car without AC today its 46 degrees and humidity is 76% ( no need to tell you more about this damn weather)

guys again i really need your help in here

seems we are having the exact same problems read my post above

 

[RayBan GST]

RONI WAN,

i created this thread since a while ago but till now i can not fix the problem , i hope that the wisemen in here would help us out

 

[roni-wan]

have you changed the expansion valve? someone in the upper posts mentioned it and stated having a bad valve would put a high load on the engine like we are having

my engines takes a lot of effort to rev when a/c its on and also see boost coming up at low revs

live in mexico with 42 degrees and 100% humidity its like hell on midday thats why i am so desperate to get the a/c working

 

[RayBan GST]

i have serviced the AC completely , i removed the compressor and change the pressure expansion valve , i have put new gas inside the compressor as well and even i changed the clutch and the bearings of the compressor with compressor oil as well.


thats not our porblem i really need some help in here

i will check my ECU today for any leaks its the only thing left

 

[rush2252]

I believe the expansion valve is over in the HVAC area under the dash on the passenger side? If its plugged it will cause issues similar to what you've mentioned.

This is just a brainstorm. Are you still having idle surge or just low idle? and 14HG is rather high for a 2g. Im seeing like 17hg @curb idle 800rpms.

Double check for boost leaks clean the TB make sure the intake and TB gaskets arent leaking. Clean the area where the ISC seats. Unplug the ECU for a few minutes after you do all of this. Start the car and dont touch anything let it idle for several minutes. Then turn on the a/c and adjust the BISS to get the idle around 800 +/- 500rpms turn off the A/C post results

Can you hear a change in the idle whenver you turn on/off the A/C switch? The ISC as steve said should open up and idle the car up with the A/C on and close off when the A/C is off. If you having performance issues with the above temps you could be getting knock from Intake temps being too high. My 2g runs like a dog in the day time. Its 100* F here in Oklahoma with about 75% relative humidity I feel you pain, I drive a black car as well and the A/C is taking a poop slowly but surely.

 

[RayBan GST]

thanks Rush

here is what i did exactly :

did a boost leak and found leaks in the shaft seal ( throttle body and idle screw) i fixed them both and i bough a new idle screw with o ring

cleaned the throttle body
cleaned and changed several times the ISC
i restarted my ECU several times by unplugging the battery ( i left the car idles for 10 minutes before i start the AC )

NOTHING is fixing this problem if the car idles at 800 rpm without ac then i switch on the AC it dies. i have to make it idle at 1500 rpm in order for her to idle down at around 700 rpm but again between shift it stalls and sonetimes it reaches to 200 RPM ( BAD BAD vibration)

for the performance i am sure its beacuse its very hot the ecu is pulling timing and make it slower ( its fine with me this is not my issue )

vaccum with ac is on is 14 and sometimes 12 , when ac is off the vaccum is at 18-20

 

[roni-wan]

the expansion valve its in the box that´s behind the glove box

vacuum should be around 18-20 without the a/c and about 16-17 with it.

what calls my attention its the high load on the engine with the a/c, car feels so heavy like the compressor its about to lock up.

I´ve driven another friends eclipse and with the a/c on car feels really good no heavyness also vacuum its about 17 on his car.

 

[a-pissed-guy]

the car feels really really heavy with the a/c on. I feel like takes a lot of effort for the engine to move with the a/c

I get the same thing when I drive. If I hit the AC button it bogs down a lot. No clue why.

 

[mnr88talon]

ISC = Idle Speed Control

I have the same problem with my idle dropping when the AC is turned on and it was the ISC. My way around this is to not use my AC and only turn it on while the car is moving, then turn it off when I come to a stop.

i have this same problem too.. passengers hate me for this when were stuck in traffic

 

[steve]

I've owned the car since day one and it always was slow with the AC on.
It doesn't and hasn't ever had an idle problem from it. It will idle higher with the AC on when things are working as they should not lower.

 

[roni-wan]

I´m pretty sure its the expansion valve car feels like crap when a/c on, don´t have problems idling just feels reall heavy and thats my concern

Talked to a friend who is parting out his car will send me the box that contains the expansion valve and will change it all.

will let you know how that worked

 

[RayBan GST]

so now what is the solution of our problem ??? the IDLE problem

 

[roni-wan]

the idle problem think its related to the huge load on the engine when the a/c on thats why it feel so heavy and vacuum goes so low should be -17-16 not below that, I get -15 even -14 and that because i have idle set up to 1100rpms via dsmlink

if the expansion valve its the problem maybe your system get overpressurized or something like that, not allowing the compressor to spin freely

 

[RayBan GST]

Hi Roni Wan

i have changed the expansion valve as i mentioned to you before but trust me its not the problem


5 minutes ago i removed the gas from the AC system and i reload it again ( i put less gas this time) i did not put too much gas inside the system and now my car is not loosing too much power when the ac is on and it feels better, however the IDLE and the surging is still there


vaccum is still low and nothing changed only now i feel that the car has some balls with the ac on but again my problem is still there