2002 Chevrolet Trailblazer EXT 4.2L Engine. It died on me the other day I got a boosts.  Later that day I got a new battery. They check the alternator and its fine. We notice the back AC was on and the truck turns off even when we turn on the ac

or heat on the front it shuts. Off what could be the problem.


Answer: Stalling with the A/C on at idle is usually caused by carbon build up in the throttle body. The throttle body bore and plate should be cleaned with a carbon cleaner spray. Electronic throttle systems are very common to this. Watch this how to clean throttle video. After the new battery, idle speed memory would have been lost, so it is trying to learn a new idle, but the carbon is making it difficult.

2007 Trailblazer. Engine Size : 4.6
Question : .my trailblazer will sometimes be hard to start. it cranks over several times before it will start then when i take off it surges up to 2000 to 2500 RPM's for about the first 10-20 minutes of driving it.


Answer: You could have a vacuum leak, restriction in the air intake or PCV system. If the check engine light is on, the computer will have information stored that can help in diagnosis. There is also an electronic throttle body on your vehicle that could be bad. That usually affects driveability and can have the symptoms you describe. Another possibility is a faulty PCM (computer) or wiring. Usually this will set the check engine light on as well or cause multiple other issues. This will probably have to be checked out at a reliable shop, as it can be a few different things. One suggestion, if you need to replace parts, it is always best to use genuine GM replacement parts.


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    • Guest - Joe Motta

      I have a 2004 envoy xl with same stall problem cleaned throttle body but same problem still there once in a while stalls at idle mostly at red light

    • Guest - Tom

      In reply to: Guest - Joe Motta

      Make sure you put the hose on the underside of the air intake box back on. If this is not installed, it will cause a vacuum leak.

    • Guest - cedric collins

      i cleaned the throttle body, but now it's worse! Also the service engine light is blinking. The engine still turns off when i turn the A\C on. Please help
      You can email me at crcollins82@gmail.com

    • Guest - Guest 1

      I have 07 Trailblazer run perfect no issues. I notice that every time I turn the AC on after a while the check engine light comes on. I turn the AC off and drive without the AC on and the light goes off. Any idea what's causing this issue?

    • Guest - Tom

      In reply to: Guest - Guest 1

      You will need to have the computer codes scanned. This can be done for free at many of the large national parts store chains.

    • Guest - a.m.

      So happy I took the advice from this site. .I have a 2003trailblazer &when I turned ac on truck turned off"..I cleaned the throttle body part myself ..and it don't turn off no more truck is like new again all comments help"!..

    • Guest - Richardson

      2002 Chevy Trailblazer struggles to shift in first gear and makes a loud noise like I was revin the engine and the rpm goes buts, then it takes until I get to the next light and needs to move out again. How do I fix that?

    • Guest - Phil09

      In reply to: Guest - Richardson

      Well, i can't really understand what your problem is, but it sounds like a transmission problem and an internal engine noise.

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    The hydraulic brake system consists of the following:

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    Hydraulic Brake Master Cylinder: Converts mechanical input force into hydraulic output pressure. Hydraulic output pressure is distributed from the master cylinder


    Common Engine Codes

    Evaporative Emissions Leak Code P0440 - P0455

    P0440 - P0455
    The control module tests the evaporative emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge valve OPEN and the EVAP vent valve CLOSED .