Stalls with A/C on at dead stop
06-25-2013, 04:47 PM
#1
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Car: 87 Trans Am, 99 WS6, 16 Mustang GT
Engine: LB9, LS1
Transmission: 700R4, T56
Axle/Gears: 3.42 Posi, 4.10 Posi
Stalls with A/C on at dead stop
My car has been stalling at stop lights with the A/C on. It'll be ok for about 30 seconds, and then it will start to hiccup and that's when it'll stall. It idles at around 700rpm with the A/C off, with it on it sits at about 600rpm until it stalls. What can I do to fix this? It's quite irritating having to pop it into neutral at a light.
06-26-2013, 08:43 PM
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Car: 87 Trans Am, 99 WS6, 16 Mustang GT
Engine: LB9, LS1
Transmission: 700R4, T56
Axle/Gears: 3.42 Posi, 4.10 Posi
Re: Stalls with A/C on at dead stop
The cooling fans come on at exactly when they're supposed too.
Should they come on directly with the A/C? I've never had an issue with overheating. At idle with the A/C on, it'll never go over 240, even with the hot weather.
Should they come on directly with the A/C? I've never had an issue with overheating. At idle with the A/C on, it'll never go over 240, even with the hot weather.
06-26-2013, 09:11 PM
#4
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Re: Stalls with A/C on at dead stop
Sounds a like bad tps or Idle air valve. Im not 100 percent on how maf cars are suppose to idle with the ac off and on, but my car idles at 600 with out the ac on and about 620 with ac on, and idles smoother actually. If your car doesn't stall with the ac off, sounds like a bad idle valve. Because your idle air will adjust position with ac off or on
06-26-2013, 09:35 PM
#5
Re: Stalls with A/C on at dead stop
There is a pressure switch on the ac line that on your car is normally closed 89 is n/o. When the ac is requested on d11 of the ecm. When this green wire is open the cooling fan is commanded on and the target idle speed is commanded up for the additional engine load.
06-28-2013, 07:01 PM
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Car: 87 Trans Am, 99 WS6, 16 Mustang GT
Engine: LB9, LS1
Transmission: 700R4, T56
Axle/Gears: 3.42 Posi, 4.10 Posi
Re: Stalls with A/C on at dead stop
There is a pressure switch on the ac line that on your car is normally closed 89 is n/o. When the ac is requested on d11 of the ecm. When this green wire is open the cooling fan is commanded on and the target idle speed is commanded up for the additional engine load.
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06-28-2013, 09:12 PM
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Car: 87 Trans Am, 99 WS6, 16 Mustang GT
Engine: LB9, LS1
Transmission: 700R4, T56
Axle/Gears: 3.42 Posi, 4.10 Posi
Re: Stalls with A/C on at dead stop
Where is that switch located?
07-08-2013, 07:43 PM
#10
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Car: 87 Trans Am, 99 WS6, 16 Mustang GT
Engine: LB9, LS1
Transmission: 700R4, T56
Axle/Gears: 3.42 Posi, 4.10 Posi
Re: Stalls with A/C on at dead stop
Is this the switch? It's the only one I can find on the A/C high pressure line, but one of the wires is blue, instead of dark green as that diagram suggests.
If it is, I tried jumping the terminals on the connector with a paperclip (as you can see), but neither fan came on when I did. When I take out the paperclip, one fan on the driver side comes on. The car still stalls though, w/ or w/o the clip.
Last edited by NowhereFast; 07-08-2013 at 08:39 PM.
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