dayid wrote:Any chance you could give me a little more insight into what went wrong with your blower? My late '85 720's blower had been intermittent for a few days and then completely quit. I am getting 12v @ the red wire (the two that go to the blower), but the grounding to the blue wire (of those same two) is bad. Is that why you had to pull your dash? How hard was pulling the dash? Any tips so I don't have to pull out any more hair trying to correct this?
Here's the deal. The real reason I pulled the dash was because I had to replace the heater core. No big deal. It's only 8 bolts and 2 electrical connectors. I did however need to pull it to fix the connector issue I had, because I couldn't solder new connections where they were.
Pulling the dash will make this WAY easier to trouble shoot though... it's really up to you. Make a thread and post up what you find. You can ask for help there too based on what you find.
Here are some pictures to let you know how to get the dash out of your 720.
Start on the driver's side.
Take the column surround off. You don't need to pull the wheel to do this. Just make sure you get all the screws out so you don't break the surround.
Dash bolts: 10MM
2 here
There is 3 across the top. I could only shoot the center one.
One here by the e- brake.
Since you're here, pull this electrical connector apart. PUSH the tabs together, not pull. This goes for all connectors on the truck. Should have a blue one and a white one. For the dash harness.
Passenger side. 2 bolts here:
If you've got the package tray, you've got 2 more screws.
Pull the dash out A LITTLE. Go back to the driver's side, reach up behind the speedo and disconnect the cable. I think you have to twist the connector then pull the cable. Can't remember. Then the dash should come up and out. Mind the blower ducting. Some may fall out.
Now, if something looks like it's not coming out like it should, be careful and look twice. I may have forgotten something. Also look and read through a few more posts. Look through all my posts. I usually took pretty good pics, but sometimes I didn't. Look and make sure you know how everything comes apart. If you can't figure it out, ASK. Try not to break stuff. It's hard to find.
Now, based on my experience, there's only a couple things that could go wrong, but instead of throwing parts at it, you really need to sit down with a multimeter and a wiring schematic and figure it out. I would go in this order
If you're testing components with an ohmmeter, they need to be DISCONNECTED and isolated before you test them.
Blower motor- should have RESISTANCE. Should not read 0 or OL that means you've got an open or a short. I'd say it should be between 5K and 15K ohms
Blower resistor- If it looks burned up, it probably is. HOWEVER, if it was, the blower should still work on high. Resistances for the resistors are usually listed on the board.
Fan switch- You should have low resistance in 3 of the positions and OL in the off.
Fan switch connector- If you look in the first post, mine was melted. If I had to do it again, I'd have gotten one from the junkyard instead of what I did, but I had to get the truck running pronto.
All other connections- They could be melted, corroded or broken. Leave the fan on and start shaking wires. You'll find it if that's your problem.
I think that should do it. Good luck.
I just wanted to know how your setup was working... It just seems as grinding the tabs off the hubs may make for a lose fitting wheel... or does it?? 
or a set of 16" '02 GMC rim.... 
either way i'm guessing i'm going to have to order them from somewhere outta state... is there somewhere online to find parts like this??? i have tried my local JY and also Pull-A-Part (all they have anymore is car/truck hulls, they all been cleaned out already)
this is just terrible...
