Yeah yeah, maybe the radiator fan will be bigger… but this one is going to cause me some headaches.
Working on the A/C I’d like to use the “modern” fan as the old one is tired and slow. Here’s the Fan (and some parts of the controls) out of the donor truck.
…but wait, what’s this doohicky?
Here it is attached to the fan motor. Wires everywhere!
Seeing that I’m going to want to do some testing, I wire up a toggle switch to a car battery (with a fuse! I’m not an animal!).
I run that into a junction box and mount a toggle switch on the top (the fuse is inline on the hot side inside the box)
She ain’t pretty, but it works. the switch is more than rated for anything I’m going to be pulling through there.
Now, back to the blower motor… I break out the full shop manual for the donor truck and dig up the wiring diagram for the hvac fan blower motor.
Well that helps!
If I read this right, if I put power to 2 orange and ground black, it should blow full blast.
(fiddling occurs in the background…)
oof. Nothing.
I test out the motor the old fashioned way (direct wire hot and ground to a 12v car battery). It works!
Huh.
So I pull the plug out of the motor and use the multi-meter to see if the leads are getting juice with that setup.
YUP 12V at red testing against a known ground.
Well, is ground not making it back? I turn off juice and check the black end, does it have continuity with the known ground?
YUP, continuity from the black tip to the known good ground.
Huh.
Another change dealing with electrics: changing over the ducks from being vacuum actuated to being motor actuated. Here are the actuators out of the donor.
I figured out with some fiddling that brown needs to be power, then you ground out then there will be one lead for clock-wise turning and 2 leads for getting it to turn counter-clock-wise. That’s getting somewhere. that gives me some (kinda weak but functional) actuators to move diverters around.
What do I mean by moving diverters? So here is one that’s open:
and then closed
It basically opens and closes areas where air can navigate. On the old truck they were actuated with a vacuum system. The vacuum actuator is under my hand. The ones from the old truck are shot and honestly, they are notoriously suspect. Vacuum systems almost always leak and give random weird behavior in duct work. So can I adapt the old truck to use the new style actuators?
Here you can see the position at the actuator when the diverter is “closed”:
…and here it’s open.
There is a push-rod that comes out of the vacuum actuator that pushes the lever which rotates the pivot for the door.
My first through is to just mount the actuator above the door and figure out how to attach it. However, there isn’t sufficient clearance to the firewall. Rats!
Maybe I can mount it where the vacuum actuator was and add a little lever arm to replace the push from the vacuum actuator.
I might need to mount it upside down so that the wires aren’t poking out toward the passenger’s legs.
To see the new actuator work, I wired it up to the test toggle switch and put the “new truck” diverter onto the actuator so you could see it move.
Click here to see the actuator wiring and see it in action.
The idea is when the A/C or heat are turned on, power would be set to the actuator to open the vent and allow air into the cab. When it’s turned “off” then the door should close. The thing is, I don’t think the actuators stop pushing. they reach the physical limit of how far they can go, but the little motor in there keeps on choochin’. I may need to add stop-switches to limit how far it goes. I think just some micro-switches would do the trick if they are needed. I may need them regardless as I think the actuators swing too far! The door needs about 3/4″ swing, but the actuator (min 3/4″ arm) swings approximately 80 degress which means that at 3/4″ arm length minimum that’s approximately 1.5″ swing. which is twice what’s needed. Hmmm. Gonnna have to get clever.
If I get it working without the switches, I’ll add them later. They require a modest change to the wiring design.
I also need to find a way to fit the evaporator and fan under the dash, rework some ductwork and make a box for the heater core. Let’s figure some of that out.
If I could, I would use the donor truck evaporator and fan. It’s a pretty big plastic box that goes into the cab under the dash.
Here’s where it has to fit:
Just looking at all this componentry together, it clearly won’t fit under the dash. this is a shot from “above” that includes the donor truck’s A/C bits and the stock truck heat/defrost ducting:
The donor trucks stuff includes the heater core, the A/C evaporator, and the fan all in one bundle. I decided to see how much of it I could cram in there if I just trim off all the extraneous plastic. It passed the first blush with the tape measure so it’s worth trying.
I trimmed all the stand-offs from the back and kept where the high/low lines run through the firewall.
Looks promising… I’m within a few inches of fitting without cutting the firewall. that’s promising enough. So, I cut the firewall for the line relief to go through.
It looks good…until I figure it out’s about 1″ too wide for the dash. Man. So close.
grumble grumble. I had to put it down for a few weeks and ponder.
Here are the dilemmas:
- Because of the engine bay space the fan needs to move inside the cab. I can use the donor truck fan (multi-speed and much more flow than the stock original)
- I can keep the heater core in the engine bay but I’ll need to craft a box and air diverter
- I don’t think I can use the donor truck a/c evaporator. I know I can’t use the condenser.
- TBH I would like to have air coming out of the dash (or even under the dash) rather than through the heat/defrost vents. So maybe an a/c kit is worth doing?
Regardless of if I go with a kit or craft my own parts, I’ll need to have someone (not me) who can vacuum the system, make up hoses, and install the dryer and add the cooling stuff. That stuff is nasty and IMO not worth me trying to do on my own. In this case it might be best to get a shop in the discussion and see what they think is my best route.
Yup. Time to ponder. Keep your cool! Go wheelin’ ! This was a good day with good people on Switzerland trail near Nederlands, CO.
wrenchingseason 