1972 Duster A/C - Heating Blower

[1BAD72]

Hello... I have run out of things to check on my heat/A/C syatem. My problem is that the blower for the heat and A/C is not coming on from the control panel.

So far I have:

• checked the fuse,
• verified the blower itself works in all 3 speeds by applying 12v to the line going into the 3 resistors that control the blower speed,
• verified the hi/med/low blower switch works (verified switch is good using multi-meter and again when I powered up the blower),
• changed out the control block that holds the 5 pushbuttons (NOS)

I don't see a blower motor relay in the wiring diagram for a 1972 Duster. The vacuum pots for the vents are working and the A/C compressor clutch engages when I push in the A/C or MAX A/C button. I may need an A/C charge but I don't think that will prevent the blower from coming on.
Any suggestions what else to check? Thank you...

 

[moparbob71.2]

So I think this is your control. Your fan speed will only work if the upper slide is in one of the positions other than off. Hot and cold should not matter.
What happens when you put the fan on hi and the upper slide on vent?

 

[1BAD72]

View attachment 1715344476
So I think this is your control. Your fan speed will only work if the upper slide is in one of the positions other than off. Hot and cold should not matter.
What happens when you put the fan on hi and the upper slide on vent?

Hello and thanks for the info. That control is not what I have in my 72 Duster. The picture below is from Google but that's the type I have. The first pushbutton is "OFF". If I have any other button pushed in the fan should come on. The fan switch on the left is a selector. It's Low, Med and High. The slider on the bottom is temp but should not impact the fan coming on.

 

[RedFish]

have you verified power coming to the switch from the fuse? If it works with supplemented power supply it should work with OEM power supply.

 

[1BAD72]

have you verified power coming to the switch from the fuse? If it works with supplemented power supply it should work with OEM power supply.

You nailed it... the black wire that is one of 3 wires in the red connector that goes into the control block was dead. Traced it back to the fuse box. I replaced it and its working 100%. What made it very hard to diagnose is that I bought a new control block that houses the pushbuttons and even though it was new old stock it was defective.
Thanks everyone for the input...