How do you install a defroster on a GMC Truck?

1. Install the mode actuator as an assembly with the actuator cam. Line up the heater/defroster valve lever with the mode actuator cam slot. Line up the A/C valve lever with the mode actuator cam. 2. Install the mode actuator mounting screws to the HVAC module. Tighten the screws to 1.6 N·m (14 lb in). 3.

Where is the defrost vent on my car?

It is located above the driver side gas pedal. There is one vent tube that needs to be removed or pushed off to the side. There are 2 screws about 6mm and a small wiring harness to remove. It’s tricky to get to but not overly difficult with a trouble light and a small socket wrench with an extension.

Where is the flow actuator on my car?

I ended up taking it into a dealer and the scan revealed code B3779 – airflow mode actuator stuck. I picked up a new flow actuator at a local parts store for $140 and installed it myself. It is located above the driver side gas pedal. There is one vent tube that needs to be removed or pushed off to the side.

Which is the hardest screw to put in a defrost vent?

The bottom screw is the hardest to put in so I suggest you start with the top one after you have the actuator and ‘fan’ lined up correctly. Reconnect the wiring harness and then the negative battery cable. After you start the vehicle, you should see the actuator cycle and then try managing the air flow through the controls.

How to change the mode actuator on a 2003 Chevy Silverado?

This repair of course should be generally the same for 2003 through 2007 Classic series trucks and suvs. Remember to preset the controls to the split defrost / floor position before removing the old actuator. If needed, use a small screwdriver or the edge of a quarter to rotate the actuator into the correct position.

What to do if your defrost is not working?

Place the ignition switch to the OFF position. Remove the HVAC/ECAS fuse for a minimum of 10 seconds. Install the HVAC/ECAS fuse. Start the vehicle. Wait 40 seconds for the HVAC control module to self-calibrate. Verify that no DTCs have set as current DTCs.

When does air come out of defrost vent?

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Why are the vents on my GMC Sierra stuck?

The most common symptom of course is lack of control over the vent output position and normally it will be stuck in the defroster only position. If it is not currently stuck in the defroster position but you are changing the actuator anyways. make sure that you set the vent position to defrost before starting this procedure. You will see why later.

Why does air come out of the defroster vent only?

At light throttle or when you were on level ground, it was ok. Start up a hill or give it gas to pass someone and the AC would start blowing out of the defroster vents. It still used vacuum. Had to have it fixed one time. One vacuum line from the rear of the intake runs to the control valve under the dash. It must be different from the trucks.

How do you install a defroster on a GMC Truck?