HVAC Control- All settings work except defrost

[hedbutter]

Hello All- I've been reading through a ton of search responses, and it looks like its the blender door, but wanted confirmation/where to get parts to fix. My 1990 vents work in the floor, vents (middle?), but when i go to defrost only, i get it partially through the defrost and floor. Anything i should check before i start replacing? Also, i plan on getting the AC fixed at some point (may not be until the spring though) so would it be better just to deal with it until then?

[Dzimm]

13 minutes ago, hedbutter said:

Hello All- I've been reading through a ton of search responses, and it looks like its the blender door, but wanted confirmation/where to get parts to fix. My 1990 vents work in the floor, vents (middle?), but when i go to defrost only, i get it partially through the defrost and floor. Anything i should check before i start replacing? Also, i plan on getting the AC fixed at some point (may not be until the spring though) so would it be better just to deal with it until then?

Check for rodent nests before replacing parts.  Stick you head under the passenger side of the dash and push that hvac door open and see if you see anything. 

[8valvehero]

Does the fan stay spinning at the same speed when you select defog, or does it slow down / stop?

[hedbutter]

Fan appears to be the same speed, just split through the different settings.

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[Ωhm]

On 9/12/2018 at 9:41 PM, hedbutter said:

Anything i should check before i start replacing?

 

Disconnect vacuum source to HVAC unit. Default (no vacuum) is defrost only. 

[hakukamana]

What Control unit do you have ? Heater or AC/Heater? You do have a defrost door on the heater core housing, no vacuum=wide open. The panel door is closed, and the Floor Door is closed, vacuum. Green plastic line to dashpot for defroster door, from #9 on heater control switch, the heater controls also need to be in the heat mode. The heater controls are all rubber connectors and plastic lines to the various dash pots and  the heater control switch.