tank1949

While working the AC air selector on dash for floor, face or defroster, the face part turns (in dial) but no air comes out. Heat and defrost selector moves air accordingly. I suspect problem is inside control box on floor, but I am not 100%. Anyone have schematic of this box. I don't know its name???

oilcanhenry

I know of no such control box on the floor or your Chevy. Where did you get this notion? I have a 1998' Chevy K-1500 and I can assure you that there is no such box on the floor. Might be you have a bad actuator motor, but those are located in the climate control box underneath the dash

tank1949

I am probably calling it something that is incorrect. It is the long black box looking device that heater air comes out and an actuator is connected. Moving the selector on the dash, I can see this actuator moving. Heater and defrost only work.

oilcanhenry

Thats your Climate Control Box under the dash. It houses the heater core, the A/C evaporator and various acutator controls to route the air to different parts of the cab. Is your A/C system not operating?

Gumby22

What you need to focus on is the mode door actuator and door, located on the left end of the HVAC housing. You should be able to see it from the driver foot well, though removing the trim panel from under the dash might be necessary to replace it.

If you’re only getting air from the defrost then most likely the actuator has failed, however it’s also possible the door is jammed or broken (or both).

With the key on, watch the position indicator on the actuator - if it’s not rotating while selecting modes, verifying the power, ground and control feeds to the actuator are the next step.

If it’s humming like it’s trying to rotate but there’s no movement, the internal gears of the actuator have stripped and it requires replacement.

If it is rotating but the mode isn’t changing, remove the actuator and try to move the door by hand using the splines for the actuator - you’ll know if the door’s in tact because there’s a certain weight/feel to it. If it’s broken (specifically the shaft) it will be very easy to turn.

If the door is jammed, you may be able to free it depending on the obstruction. If it’s broken, the whole HVAC housing needs to be removed in order for the door to be replaced.

The HVAC housing is illustrated below. I did a write up on HVAC actuators a while back that will provide more in-depth info if you’re curious.

https://chevroletforum.com/forum/gen...urious-102672/

tank1949

THX!!!! I am thinking something has jammed it too, since I see spindle on Mode actuator moving and this is a 95 truck. Something may have broken internally. I will remove and see if there are internal issues. Once again, THANKS!!!!!

However, before I take this apart, in your opinion, could the problem possibly be one of the other two actuators? I am thinking no!

Gumby22

No. The mode door actuator is the only one used for selecting between defrost, panel vents and floor (or any combination of those modes). The other 2 actuators are for temperature blend control and recirculation/fresh air and do not affect mode door operation.

If the position indicator on the mode actuator is rotating, it’s likely the mode door shaft is broken. This can typically be confirmed by turning the control dial to full defrost or full floor and watching for the position indicator to continue rotating in a full circle; however I can’t recall if the 1995 actuators have any internal stops so that may not be the case.

In order to remove the HVAC housing and replace the door, the entire dash and support structure (Instrument Panel carrier as it’s often called) will need to be removed first.

Harbor Freight sells relatively cheap inspection cameras (bore scope) - if you’re not entirely sure the door is broken or otherwise obstructed, it would be worth purchasing one because then you’d be able to view the door directly via the vents and determine if pulling the HVAC housing is necessary.

Believe me when I say that it’s not a job to just jump into - I’ve had the dashes out of at least 6 vehicles ranging from a 1996 Silverado to a 2015 Dodge Ram and it’s a process that requires time, patience, and organization. You will be thankful not pulling the dash if you don’t have to.

tank1949

I believe you, and I will be upside down working on it in the heat.

THANKS!!!!!!

tank1949

AC blows out of that box and not through the dash vents.

Gumby22

What box?