This has really gotten me stumped. Still high only, here is what has been done so far:

Heater switch
Relay (under hood w/ replacement clip)
Blower motor resistor
Vac lines (fire wall to under hood) select switches work now
Volt checked at switch all within spec
Volt check at relay (seems to be within spec)
Blower motor checked (seems fine but doesn't get voltage until its on high)

Heater core cleaned
New radiator
New water pump
replaced most heater hose
(this was all done when I rebuilt the top end of the motor)

But I figure there is still an issue with the HAVC system due to cannot get heat to the rear air, also doesn't seem like the vac valves are working correctly when switching from AC to Heat. Is there something I am missing?

Thanks in advance

 

Check the Dark Green wire with White Strip going to Pin 87a of your fan relay for power when the switch is in any of the lower speeds.

Also check the Tan wire going to the resistor pack for power.

The tan wire feeds power to both the switch and resistor at the same time. You have power to the switch for it will engergize the relay for high speed.

 

Green wire w/ white strip Pin 87A gets 0 at high and 0.03 on all other settings (rear fan works on all settings) Front fan works on High only

The relay is new
Tried this with both the new and the old relay (same results)

 

What about the tan wire going to the resistor pack?

 

If I remember correctly that only had voltage on high, I would have to recheck after the snow storm passes and I get all dug out.

 

On the reistor pack wiring you should have the following.
Tan = hot all the time (with key on and HVAC controler on)
no info on speed 1 on my diagram.
Lt. Green = hot on speed 2
Lt. Blue = hot on speed 3
Dk Green/wht = carries the power to pin 87a of the relay.

 

K checked this is what I have:

Tan wire to resistor has power
as I switch the fan speed switch power jumps to each on the resistor

Have power per the switch
Dk Green / wht
Lt Blue
Lt Green

Tan all speeds

pin 87a has power

But still only have fan speed on "HIGH" only

as stated NEW
Relay
Resistor & Resistor pig tail (clip) as it was burnt badly (used Chryslers repair kit)
Switch

Only thing I have not replaced is the blower motor, but it works on high

 

Before replacing the blower motor jump on the relay harness pins 87 and 87a. This will dump the power coming from the resistor pack directly to the blower motor. If that does not work try a hooking up a headlamp bulb to pin 87a and the negative post of your battery.

If the lamp works at least on speed 3 then replace the blower motor, if it does not light then there is still a problem in the resistor circuit.

 

Jumper from 87a to 87 fan took off, so traced down the Green w/ white strip wire and found my short.

Thanks Mobile Auto for the reference information

P.S.

After this mis-hap I went and bought a FSM so that I can trace things down myself. Next project will be the Odometer (next post due to FSM is about 6 weeks out)

 

How did you check the switch? I am assuming you mean the speed switch inside the van. I am having the exact same issue. Replaced water pump, radiator, all hoses (not becuase of this issue), blower resistor, blower relay, wiring pigtail from relay to resistor. I still cannot get anything other than position 2 and 4 (high) to work.