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Mr GOODWRENCH, ASE Certified Technician
Category: Chevy
Satisfied Customers: 184
Experience:  MASTER ASE TECH, 10+ yrs GM experience
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I have a 2003 Chevy Suburban. My ac blows cold, but only through

Resolved Question:

I have a 2003 Chevy Suburban. My ac blows cold, but only through defrost vents. starts blowing correctly when i first start car. Then it switches to defrost right away even though the display indicates dash vents
Submitted: 7 years ago.
Category: Chevy
Expert:  Mr GOODWRENCH replied 7 years ago.
Hello I will be helping you with your Suburban. Do you have automatic controls or manual?
Customer: replied 7 years ago.
auto controls
Expert:  Mr GOODWRENCH replied 7 years ago.

Okay here is a recalibration procedure. This procedure will relearn the actuators position, When there is a problem with an actuator it will default to a set position. The mode default is the defrost vents. If this procedure does not correct your problem then the mode actuator will need to be replaced. Let me know if you have any more questions or if I can assist you further


  • Clear all DTCs.
  • Place the ignition switch to the OFF position.
  • Install the HVAC actuator.
  • Connect all previously disconnected components.
  • Remove the HVAC/ECAS fuse for a minimum of 60 seconds.
  • Install the HVAC/ECAS fuse.
  • Start the vehicle.
  • Wait 40 seconds for the HVAC control module to self-calibrate
  • Customer: replied 7 years ago.
    ok. it seems to be okay. thank you. i have some other issues that all started about the same time. I was replacing my fuel filter so i removed neg battery terminal and relieved pressure on system. when i put all back together is when i got the defrost symptom and a rough idle. you helped with the defrost issue but still have rough idle and stall at idle. Any advice as to what i may have to do after replacing fuel filter to reset idle speeds or anything else?
    Expert:  Mr GOODWRENCH replied 7 years ago.
    Okay the rough idle is coming from the throttle body. The throttle body has learned the idle and has accepted the build up of gunk around the throttle plate. You need to clean the throttle body. Remove the snorkel tube and take a rag with some carb cleaner on it and remove the build up. The engine needs to be off, you will see the gunk clean the bottom and top of the body, you will need to hold the throttle plate open to get it clean. Do spray too much inside the body. Reinstall the snorkel tube and start the engine up. It will run a little rough and smoke a little this is normal. After it smooths out the idle will be fine. Let me know if you have any questions
    Customer: replied 7 years ago.
    I will return and click accept answer. Just wanted to say thank you. everything i read was very vague and pointed to the EGR and IACV. My only other question is do I remove the throttle body or just the snorkel you referred to in your post? How else would I clean both top and bottom of the throttle body? Sorry, i'm just a broke novice trying to avoid a very costly repair at the dealership.
    Expert:  Mr GOODWRENCH replied 7 years ago.
    No problem, just remove the snorkel tube and open the throttle blade with your fingers and hold up open and clean it this way. Any more questions feel free to ask
    Mr GOODWRENCH and 6 other Chevy Specialists are ready to help you
    Customer: replied 7 years ago.
    hey thanks,again! worked like a charm.