AC/Heater Blower CFM

Muskoka · July 7, 2003

My AC/Heater blower in my 1996 Yukon works on all speeds, but just doesn't seem to move a whole lot of air. Is there a filter or screen that I can check to see if somethings blocked up?

I know about the cabin filters in the new body style trucks - I had a '99 Silverado - but I don't know if there is anything similar in the older trucks that I can inspect.

gnutruk · July 7, 2003

Hi Muskoka :

Sorry I don't know much about the older trucks, but I made a mod on my 2002 1500 that might help your problem, IF your interior setup is similar to mine. Even if what follows doesn't apply to the seating/ducting configuration in your truck, I will briefly explain what I did, in case other owners with more recent model years have an issue like yours.

Even though I thought the force of the A/C - Heater - Defroster was OK, I wanted better, especially the defroster during foggy and cold weather conditions. I felt this way even when the truck was brand new, so I was able to rule out a clogged cabin air filter as being the cause.

I have the extracab with bucket seats and the new-style center console, and there is a ducting system made of black ABS-type plastic that emerges down from under the dash and travels along the driveline hump underneath the first section of the console system. It then splits into two branches as it passes around the large center storage bin, outletting at the upper back of the center console, for the rear passergers. You can see this duct in the new model trucks by lifting up the cup holder tray that's just in front of the main console.

Well, I didn't think supplying heated or cooled air to the back through that ducting was so important, since the entire cab volume isn't all that big, and anyhow there are two other rear area ducts that spread warm/cool air backward from under the front bucket seats. I asked myself; "What's more important? Having an occasional passenger who has to wait an extra minute before they get comfortable, or the driver (me) having faster improved vision out the windshield?" The answer was a no-brainer.

So I removed the ducting, by first removing the entire console assembly (the main storage compartment and the forward unit with the CD storage bin), then cut off the most forward ("upstream") piece of ductwork where it makes a nearly 90 degree bend, and finally sealed where I cut the duct with aluminum adhesive tape.

I think the results are terrific. My guess is that the force of the air is nearly double what I had before, at each of the five speed settings. On defrost especially, at setting number five, it blasts the windshield like you can't believe. That is exactly the effect I was after.

Hope this will help, if other solutions don't work. Like I said above, if this mod isn't applicable to your truck, perhaps someone else here might want to consider it for their newer vehicle.

gnutruk

Muskoka · July 8, 2003

gnutruck,

Thanks, but that won't work for me on two counts: I have an older body style Yukon, so the air ducting doesn't route through the console, and I often run with my Lab in the back seat going to & from the field so I need to keep the airflow going to the rear.

Primarily I'm looking to learn if there is any type of filter or screen that I can check inside the passenger compartment.

As I said, the fan steps up to all speed changes: It just doesn't seem to move a lot of air.

Blue Ghost · July 8, 2003

My guess would be the evaporator is clogged with dirt or leaves, remove the blower motor from under the right side of the dash and you can clearly see the evap core inside the heater case on the left, if clogged lay a large piece of plastic inside the vehicle to guide the extra water out of the vehicle, wash out core fins with slight pressure from a spray nozzel attached to a garden hose.

After cleaning it should be good as new!

varmint2506 · July 8, 2003

gnutruck,

Thanks, but that won't work for me on two counts: I have an older body style Yukon, so the air ducting doesn't route through the console, and I often run with my Lab in the back seat going to & from the field so I need to keep the airflow going to the rear.

Primarily I'm looking to learn if there is any type of filter or screen that I can check inside the passenger compartment.

As I said, the fan steps up to all speed changes: It just doesn't seem to move a lot of air.

You may want to check and make sure the dampers are opening and closing properly. My '98 started to blow less air on A/C. I fiddled with the controls and dampers and got the airflow back. Do you notice the airflow difference between the floor and dash?