1997 K1500 A/C problem

[daronlayne]

My air conditioning is cold, but it blow out the dash vents and the defrost vents which causes my windshield to condesate. I have checked the blend motor and it works fine. I am wondering if there are any gaskets on the flapper inside the duct that may need replacing. Any help is greatly appreciated.

[MT-2500]

Originally Posted by daronlayne

My air conditioning is cold, but it blow out the dash vents and the defrost vents which causes my windshield to condesate. I have checked the blend motor and it works fine. I am wondering if there are any gaskets on the flapper inside the duct that may need replacing. Any help is greatly appreciated.

Reg or auto matic AC controls?

Check for good engine vacuum to ac/heater controls.

Check all vacuum lines plastic and rubber and vacuum ball if it has one under hood from engine back threw firewall to ac/heater controls.

Let us know what you find on the vacuum.

[daronlayne]

Has regular controls, but I don't see a vacuum line anywhere on the AC. It has a motor that controls the blend door.

[MT-2500]

Originally Posted by daronlayne

Has regular controls, but I don't see a vacuum line anywhere on the AC. It has a motor that controls the blend door.

Sorry about that.
You are right on no vacuum line on that model.

But it has 3 actuator motors.
The mode door actuator motor is on the left side beside gas pedal.
That is the one that controls air flow to floor dash and vents.
Check it for movement in all directions from dash control with no grinding noise when you switch mode defrost, dash vents and floor air.
If not switching right remove it and flip mode door by hand to make sure it is not stuck and working right.
Let us know what you find in that area.

[jdmccright]

You should be able to see the motor and the connecting actuator arms that direct the mode door and fresh/recirc door. Watch them carefully as you turn the mode knob. Do they not move at all? Do they move a little then stop? Is the movement you see a constant speed or does it slow down to a stop?

An uneven movement usually means something is sticking. It could be old grease, ingested dirt, pet hair (yes, I've seen it!), etc. I've even had the case on my own truck where the old rubber flap seals were so old they actually became sticky.

Normal movement that stops abruptly (or you can only see the motor/arms try to move) means there is something broken inside the motor. I've had the experience where a gear inside the fresh/recirc motor had a partially broken tooth that caused it to stop immediately when it rotated against the adjoining gear. In this case, since the door only rotated through 90°, I simply flipped the gear 180° so that the bad spot was never used (wish I had gotten a picture if this unique problem!)

Finally, no movement at all usually means a loss of power, bad ground, or an internal electrical break in the motor winding. A repair manual should be consulted to test the motor connectors and the wiring to it.

Hoipe this helps!