98 Blazer heating problem

As its 90 degrees out I'm trying to figure out why I can't get any air to come out the bottom foot vents. Whenever I set the selector to a step that would move air out of the bottom vents the air comes out the top defroster vents. I get between 20 and 30 in Hg of vacuum. All actuators seem to be working properly. Any ideas?

Automatic or manual AC controls?
If auto check for Body computer codes?

Is the hot and cold air part working good?
Will heat/heater part put hot air out bottom vents?

Sorry MT:

manual controls, hot/cold ok, no hot or cold air out of bottom vents. It seems like even though the vacuum actuators are working, one of the "vanes" isn't directing the air properly. Possibly the vane broke off the lever that the actuator pushes?

Default on a bad vac line is defrost so look underhood drivers side for the vac lines 5/32" and rotted ones - the last in the mess is the plastic heater control line.

I had to replace one of vanes in my 98 blazer. It is not a fun job at all. The vanes are made out of cheap white plastic and the actuator arm some how broke off from the vane inside the vent. One thing I do remember before it broke was that it was making a snapping noise whenever I changed the vent direction from the floor to defrost. But after I fixed it, it didn't snap anymore and it has been ok ever since. You may want to explore all alternatives before doing this, as you will need to remove the dash to take apart the vent assembly.....in other words...1 day job.

Vacuum seems ok so I think there are noe vac leaks.

I have replaced a few heater cores, one in a Blazer, not fun. I assume a vane is the same headache. I just have to decide if it's worth it. Having no feet heat isn't acceptable when its 0 degrees out! I'll check the prices of parts first.

Vacuum seems ok so I think there are noe vac leaks.

I have replaced a few heater cores, one in a Blazer, not fun. I assume a vane is the same headache. I just have to decide if it's worth it. Having no feet heat isn't acceptable when its 0 degrees out! I'll check the prices of parts first.

If you decide to fix it get a good repair manual and study the system and figure out what door/vane has to move to get floor air and see if you can manual open and close it.
Then go from there.
Good luck
MT

I have the same snapping noise from up near the gas pedal and no floor heat. What exact part fixed your problem? Does the whole dash need to come out? I checked vacuum and that's all fine. Thanks!

98 Blazer 4x4 4.3L 155,000 mi

I have the same snapping noise from up near the gas pedal and no floor heat. What exact part fixed your problem? Does the whole dash need to come out? I checked vacuum and that's all fine. Thanks!

98 Blazer 4x4 4.3L 155,000 mi

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MT