Trying to get the vent system to work so I can possibly direct heat and/or A/C to the places it needs to go.  I have no idea what I'm doing so I'm going to try and take stuff apart and replace anything that looks broken.

Day One is take the dash off and look at the duct work and see how I might go about removing it

 

Edited May 13, 20233 yr by wildweaselmi

Check out this helpful diagram provided from another site

 

And then I have these diagrams 

 

Edited May 13, 20233 yr by wildweaselmi

So I pulled the blower motor out and hooked the wire straight up to the battery positive and grounded it and WOW it works. 

The image above you can see the power terminal on the right.  A purple wire was attached to it coming from the rectangle looking relay

With this CLOSE UP image you can the purple wire on the right that feeds the blower motor

Now I unscrewed the relay and flipped it upside down to figure out whats going on which is shown here

Then I discovered the plug that plugs into the relay comes out and looks like this

But notice where the purple wire goes on the right is all broken.  I am thinking this could be the reason why I’m not getting the blower motor to turn.  I ordered a new relay and plug from partsgeek.com and we’ll see if it works.

 

while i am waiting for those parts i need to figure out how to fix this white thing. i’m not sure what it’s supposed to look like when installed correctly

The Purple wire needs to be 12ga wire to motor, the red wire also 12ga is hot at all times, the blue wire is the lower fan speeds from resistor block. If you have selected anything but High or off the blue wire should have power at below 12v. The Blue wire is normally closed path to blower motor through relay. The orange wire powers the relay coil and closes the high blower circuit.

Quote

If you provide a fused keyed hot to brown/white wire at fan switch (64) you should have a working fan that will have all 3 speeds.

Looking at your relay plug I can see there has been high amp draw on the purple wire. This could be a worn out blower motor, bad ground, or dirty tarnished corroded purple wire connections. I am will to bet the purple terminal is loose and tarnished, and needs attention.

The wire loom and plug above is handy, but the 2 12ga circuits have the wrong size wire. The terminals can be purchased, Packard type 56 female, they come in 12ga size and 16-14 size you need both if you wish to rewire. 

With key on select low fan check for voltage on tan wire at resistor block. If you have voltage check the blue wire at resistor block, should a lower voltage. The blue should be same voltage at relay, both terminals blue ,and purple. If this what you find then the wiring to relay is working as designed. 

Place the fan switch at High the orange wire at relay should show 12v and the purple wire should show the same voltage. If no voltage the relay is bad, if lower voltage the relay has dirty contacts and creating resistance. Either of those results replace relay. 

to check the resistor block test the voltage at the blue wire in low and medium, if they are different and below 12v it is working. No voltage in high or off on blue wire.

 

I did confirm I have power at BRN [50] with key turned to on and if I jumper from [50] at the selector connector to [64] I have blower motor functioning levels M1, M2 and HI so it feels as though I'm correct assuming the heater control switch is bad??

far left pin is the brown one

top is brown so how i jumped over is just use a jumper wire like this

then just inserted into the far left brown terminal

and alligator clipped to the top where the metal clip is touching the metal of that top brown wire connection

I ordered a reconditioned one off eBay for $75 since LMC is backordered and they have no idea when. I checked with a few others and they are all sold out as well. I found some less expensive ones on eBay but they looked like they dug them out of a graveyard so I passed since I don't to have to replace it again. I like the once and done approach. Do it right one time and don't worry about it, especially when you are on a trail in the middle of nowhere by yourself. 

I'll keep you posted when my new part arrives sometime end of this month (hopefully in time for some memorial weekend trail riding)

Attaching images of the removal of the heater control for record keeping

 

Edited May 22, 20232 yr by wildweaselmi

okay replacement heater control installed and blower works, hot/cold works, selector doesn’t seem to work. no difference between defrost, heater, vent.

i’m assuming this could be vacuum issue.

i traced the source vacuum line coming in on passenger side from right side of carb.

going to get a vacuum pressure gauge to see how much vacuum is at carb and start working my way back

ACDelco 15-17220/GM 16037769 which is close to impossible to find replacement part

Here is the vacuum line coming in from the engine bay on the passenger side

 

Vacuum source was plugged into this port on the carb

 

 

Edited May 29, 20232 yr by wildweaselmi

I believe the issue is the port above the HVAC was plugged into was the Timing Spark vacuum line.  So I plugged that up with a rubber helmet and plugged into a T so it matches this diagram a bit closer (missing the check valve and vacuum reservoir)

So for less than $30 on Amazon I can get the missing vacuum reservoir (#251 above) and the vacuum check valve to hook this up closer to how its designed.  As it sits now I hooked the source vacuum line to the T as it shows in the image close to #7 and when I start the blazer up I can get defroster working but when I change setting to Vent that works but trying to go back to defrost it fails.  I am assuming I loose vacuum since I don't have a vacuum reservoir so I ordered them off amazon and we'll see if that helps.

Not getting any airflow at the defrosters