Current going to Blower Motor can be higher than Headlights - why no relay mod?

I was thinking he could check the ground at C603 back to the battery post.  Obviously the relay should provide essentially no voltage drop, but since the stock wiring provides the ground back through the blower motor switch I expect some voltage drop.

But Scott has some videos for us of before and after that he plans to post, so let's see what they sound like.

Had a chance to hook the relay up yesterday. I am really liking the Bussman ssVEC. Made hooking it up a snap.

I picked up a new motor since the old one did not survive the exploratory surgery to see if I could powder coat it.

The new one I got was 4W7Z-19805-AA (MM-929).
This also required a jumper wire: Motorcraft Fuel Pump Connector Wiring WT-56853 (4W7Z-14A411-B)

Wasn't really happy with the jumper wire design as it mixes wire gauges but I guess the relay mod mitigates that concern on the hot side although not the ground*

Since the jumper is nothing more than two connectors spliced together and it's all right beside the relay block, it was pretty straightforward to split the splice, add MP 280 female terminals and plug it in.

Ideally it would be in the grey plug since the jumper wire was pretty short but the ssVEC is split between two inputs (I am using one for the main battery and one for the aux) and the way I have it wired, the grey is aux powered.

Here you can see the jumper wire connecting to the factory plug (white to black connector) and how I split it to go into the ssVEC. Sorry, lighting isn't the greatest.



As Gary mentioned, I took some videos to try and show the sound difference between the two.

Factory:



Relay:



If you keep both videos paused, set the factory one to 19sec and the relay one to 14sec, then play them one at a time right after each other you can hear the difference.

If there are any other comparison tests I can run to provide more data happy to do so. Since the wires are right next to each other in the plug I can pull them out, throw a fuse in them and then be back to factory wiring.

Looks great, Scott.  

As for the fan noises, I tried to quantify them by using the NIOSH SLM app on my phone and cranking the volume up.  There was a bit of a problem getting things to settle before you moved to another speed, and announced it, on the lower speeds.  So those don't quite match up as they should.  But you left it on high long enough in both case that I could capture it.

  Stock  Relay
1: 55     58
2: 63     65
3: 70     70
4: 72     76

Your fan without the relay sounds waaaay louder than mine.  Did you have it on recirc?  It's hard to tell from a recording though.  My fan works on all speeds but it just seems to be wimpy all around.  I suppose I should check for a voltage drop.  If the motor works at all I can't imagine it not working all the way unless the bearing is dragging without making any suspicious noises.

Mark

Is this mod documented elsewhere on the site?  Which model Bussman SsVec?

Marki

You said in the original thread that you've put a relay on the hot side too.  I assume it's for high only too, yes?

Mark

Yeah, the recording isn't the most scientific approach for sure
It made enough of a difference that I'd do it again in a heartbeat. Looking forward to seeing if the ground relay makes more of a difference.
It looks like I had it in Normal AC. Didn't have any vacuum or ac hooked up though.

The ssvec I am using is the 000 model. I have some more info in my Camano thread but if anyone is wanting to add multiple relays it's a great option.
I spoke to the Bussman engineer that designed them a couple months ago and there is an 004 model that I think would be even more flexible in a lot of installs. None of the retailers stock that model yet although I've been contacting them every couple weeks.

Well, let's say it makes the real impact in High.
It comes into play with all levels but since the other levels aren't getting full voltage then it doesn't have the same impact.

God I hate it when motors have the TEMERITY to become generators and eff everything up.

 A big-ass diode oughta put them in their place.

Mark

HIGH is all that matters.  *cough cough*  A relay on hot and ground with a diode should do it, yes?

Mark

As I recall the recirc door in most vehicles defaults to recirc absent a control signal, vacuum or electric, so you don't have uninvited air blowing if the HVAC is set to off (or broken).  However, I might have that backwards because since vehicles default to defrost if everything is broken, you would want outside air to keep the windshield from fogging...

Actually on reflection I don't really need an ssvec -- just the relays.

Mark

Mark

Something else is up if your connector keeps melting.  My truck was an old farm truck and everything, connectors included, was covered in dirt.  I pulled all the connectors, cleaned them, and lubricated them with dialectric grease because I'm seriously anal and I've never had a problem with any overheating connectors.  When I pulled them they didn't actually appear corroded but oxidation is not always visible.  And the truth is, I didn't have any problems before I cleaned everyting.

Mark

Mark,  I changed my resistor plug the second time because I could no longer find the non-AC resistor.
The first time, it had gotten too hot but the second time it was simply because I needed it to fit.

So now I have a hot side relay and the Ford relay kit (using a Bosch relay) on the ground side in high.
10Ga. in and 10Ga. out.
In high no electron passing through the motor goes anywhere near the interior.
(unless you subscribe to theory, where there's only ONE electron and they are all probabilities)

“Ford relay kit.”  Qu'est-ce que c'est?

Reality, probability — all the same.

Mark

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F201667603086

We are totaly rewireing Brutus.  Nick made all new wire harness and pretty much every electrical accessory has relay logic.  Blower motor, headlights, power windows.  it takes alot less stress off the switches as they are only used for signal now.  If you need any help, let us know, but the diagrams that are posted are very good.

Hey Jim - is there a diagram for that Ford relay harness? Curious how they say to do it.

Gary - so you already have the ground side relay for high in place? Did I miss that in the BB thread? Would enjoy the read and photos. Going to check it out on my truck tomorrow afternoon.

Scott,  it came without instructions but I did post a couple of pics showing how I wired it in.

With the Ford part # perhaps someone with an inside connection (Myrl, Angelo?) could get the documentation.

Scott - I'm not sure there's a lot to see in pictures. But here's the schematic for my PDB

I don't know why I chose the ground side to put the relay in. Perhaps I'll add the Ford harness that Jim used on the high side, or make my own. I think there are plenty of fuse positions left in the PDB, but I think I'm out of relay positions. A relay could be used for all power to the motor, and it would increase all of the blower speeds, but mostly High.

Gary,
I think the colors and splices were pretty clear in my pics. (At least, I tried)

At first I had it wired with some backfeeding, and the relay (and motor) would stutter.
I assume when the relay closed the ground side of the coil went high and the relay would drop out.

It would be interesting to see Ford's instructions.
There must be a TSB for the vans effected.