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2002 Trailblazer stalls w/AC use
05-26-2008, 11:54 AM
Post: #1
2002 Trailblazer stalls w/AC use
My 2002 trailblazer skips and then stalls as I'm coming to a stop when the air conditioner is engaged. When the A/C is not on it seems to work ok, however from time to time the engine will have a slight skip and then idle ok (usually at about 600-700 rpms) when I come to a stop. Anyone have an idea what might be happening and are any quick and inexpensive fixes to this problem?

Thanks!
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05-26-2008, 02:01 PM
Post: #2
RE: 2002 Trailblazer stalls w/AC use
How many miles are on the vehicle?
Is the check engine light on?
Which engine / trans is in there?

Rupe
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05-26-2008, 03:10 PM
Post: #3
RE: 2002 Trailblazer stalls w/AC use
Rupe,
I have about 163K miles on the vehicle. From time to time the check engine light comes on then goes back out. And this is the original 4.2L engine, however the trans. was replaced in 2005.

Thanks
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05-26-2008, 04:44 PM
Post: #4
RE: 2002 Trailblazer stalls w/AC use
OK, most likely you mean the 4.3 liter V-6 engine which has been around for years.

What I would do is go to your local auto parts supplier. Most of them will scan for trouble codes at no charge as a courtesy to those who buy parts. At that mileage you probably have codes stored for intermittent misfire of the ignition and could use a tune up including cap, rotor, and wires. Maybe even an ignition coil if the problem persists. Also be sure to gap the pulgs per the spec listed on the emissions lable under the hood. While you have the distributor cap off double check for excess wear of the shaft (side play) and those little wires inside for cracked insulation.

If the rotor has never been off it may be stuck and require that you break it off rather than pry it off and risk damaging other parts. Use a water pump pliers to exert a rocking motion while pulling upward. If the plastic cracks that's ok. You will be cleaning the shaft with sand paper or a wire brush to make the new one go on easy. Don't forget to blow out any dust from the cleaning process and apply a very light coat of something to retard future rust on the shaft.

As for the actual stalling issue with the AC on you should take a look at the IAC (idle air control) motor, which is on the side of the gizmo where the throttle butterfly is. It regulates a controled amount of air around the throttle to maintain the correct idle speed. The passageways get dirty and the unit will stick. The extra load needed for the AC just drags the idle too low and you get the stalling problem. Ask your local parts store for something called *throttle body cleaner* which is similar to carb cleaner but less harsh on plastic parts. Remove the intake boot to expose the throttle plate and you will see a hole / passage drilled next to it, which is where you want to spray the cleaner. It may take several applications to free things up. It may even take a good soak for 10 minutes with the engine off and then start it as if the engine was flooded. (pedal down)

Rupe
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05-26-2008, 05:04 PM
Post: #5
RE: 2002 Trailblazer stalls w/AC use
Rupe,
Thanks for the info. I appreciate the help. I think I'll start with the less intrusive processes, that is, I'll start with cleaning the throttle body then move on to the plugs. Thanks again and I'll post my progress.
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05-26-2008, 09:05 PM
Post: #6
RE: 2002 Trailblazer stalls w/AC use
Hey Rupe. It is the 4.2L. It is the in line six cylinder.

FSU82. Rupe's advice still goes for your engine. His advice is solid on this.

Being way2old is why I need help from younger minds.

Visit here to see our surplus vehicles.

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05-26-2008, 09:59 PM
Post: #7
RE: 2002 Trailblazer stalls w/AC use
Thanks guy, you are correct on the 4.2 liter straight six here. I commpletely forgot about that.

The main reason I mentioned the tune up parts is the plugs may be good for 100k miles (need to check the part numbers) but quite often the wires, cap, and rotor don't last that long..... and they may be original so well past their prime. The trouble codes will show if there's an ignition misfire and that's what needs attention if that's the case.

Rupe
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