Strange HVAC problem - Vent Selector Knob

[87LC2]

Have not had this truck for long and finally getting around to sorting out the HVAC system. At first the vents would only blow from the upper dash (defrost), fixed the vacuum line that goes into the firewall and the switch selects vent location properly now.

The problem I'm having now is that the blower motor will only turn on when I remove the plastic knob and pull the metal stud out. I can turn the switch to all settings and hear it change behind the dash, but no blower motor. Once I remove the knob and pull the stud it turns on ans works perfectly. Very odd, I guess something is not making contact. Is this a common problem? Anyone know what this could be? Do I need a new climate control unit?

 

[Fast69Mopar]

It's time to replace the A/C Control head. They have definitely has their issues over the years and the older one gets the more problems can arise.

 

[87LC2]

Picked up a used unit from a guy yesterday, will find some time to get it installed this week and hopefully it fixes my issue. I'll post back if it does. Thanks.

 

[Fast69Mopar]

Picked up a used unit from a guy yesterday, will find some time to get it installed this week and hopefully it fixes my issue. I'll post back if it does. Thanks.

Yeah for sure, let us know so if other users have the same issue they know what it took to fix it.

 

[87LC2]

Finally got around to installing the new unit and it fixed the issue, works perfectly now. The heat is not as hot as I think it should be, but that's most likely another issue that I'll need to look into.

Hopefully this helps someone in the future.

 

[Mop]

The heat is not as hot as I think it should be, but that's most likely another issue that I'll need to look into.

.

Is the A/C not as cold as it should be, also? If so, it might be the actuator door.
The plastic piece that moves the door cracks over time. A company called Heater Treater sells a metal replacement.
It's at the bottom of the dash, near the floor. VERY tight to get to.

Or, it could be a simple thermostat issue. You can start there.

 

[87LC2]

Unfortunately the AC doesnt work at the moment and wasn't going to bother repairing until next Spring/Summer. This weekend I cleaned out the overflow bottle and bled the cooling system to make sure it was full and the heat is definitely a lot better. I still think it should be even hotter, might need to flush out the heater core.

What's the best way to check out the actuator door to make sure it's working properly?

 

[Mop]

What's the best way to check out the actuator door to make sure it's working properly?

There are a couple of ways, as far as I know. The easiest way is to hear it. You can hear the motor kick in when you turn the temp dial. Sometimes, you can hear it "slam" when it goes to the extreme closing. If that plastic piece is broken, you might not hear the door closing.
Another is, actually unscrewing the actuator, and watching it as you adjust the temp dial. the gears will move as you adjust.
I'm sure someone else can chime in with other methods.
I wish your A/C worked. We'd really be able to narrow it down.