Heater Motor Upgrade

[1strodeo]

Back side of dash should be a good place to make a ground, sand it to bare metal, connect the wire then paint over it

 

[Capertrj]

Back side of dash should be a good place to make a ground, sand it to bare metal, connect the wire then paint over it

So dash to motor housing that connects to heater box? I left the previous ground that’s attached on dash. The housing of the motor is the ground I assume?

 

[tvall]

Just did this over the weekend! Took me longer to do as I pulled the heater and painted it up since I had it out. Super easy upgrade.

As far as grounding, I attached the ground wire to the motor plate and then to a bolt on the top of the heater. Works great.

 

[1strodeo]

So dash to motor housing that connects to heater box? I left the previous ground that’s attached on dash. The housing of the motor is the ground I assume?

Post #391 has a pic of mine installed

 

[Crush]

like i said a bit ago. just ground it to the metal plate on the backside of the heater box. the bolts to the firewall will ground it then. my 77 was that way when i removed it and i think it had been in there since it was built

 

[DirtDonk]

The trick here of course, is knowing that your dash is actually a good ground!
Most are decent, but in some cases the Broncos are in such a state that between rust, paint, loose connections and missing body grounds and such, the dash is but a weak ground at best.
Ok, for small lights and stuff, but not as great for a heater blower motor.

I know I'm over-empasizing grounds here, as most will be fine using the dash. Just giving a heads up in case your motor is weaker or something isn't quite working right.

The best practice (after making sure that the battery has a direct connection to some part of the body) is to run a ground wire/strap from the back of the engine to the firewall. An existing bolt can be used, or one of your own making that you can also grab from behind the dash with other ground wires. This can be a new, clean common grounding point from now on. Use it to simply ground the dash, or to run the individual components to.
But it will guarantee that things work to their maximum abilities.

I've seen windshield wipers work very slowly, or not at all just because the windshield frame was no longer getting the needed flow to the body that it was welded or bolted to.
So those grounds that you put in really can make a difference.

Paul

 

[sprdv1]

Winter is coming. Order seal kit, temp control valve, 195 t stat which should be in tomorrow.

Pulled box, drilled out rivets, sanded, primed ready to go. The ground in on the bottom of dash. Chevy motor has one terminal. What’s a good spot for ground? I started going through thread but didn’t see after ten pages. Figure bump and ask.

Ahh yeah, bout that time of year lol

 

[sprdv1]

like i said a bit ago. just ground it to the metal plate on the backside of the heater box. the bolts to the firewall will ground it then. my 77 was that way when i removed it and i think it had been in there since it was built

took mine apart at one point and got frustrated, wrong part LOL still need to make this happen

 

[mpboxer]

Wanted to install this mod, but how is everyone running this heater if normal operation is 20-22 amps and our stock heater fuse is 20 amps?

https://shop.advanceautoparts.com/p...or-w-o-wheel-35587/5012066-P?searchTerm=35587

20-22 amps can be found in the "Questions and Answers" area.

Thanks!

 

[mpboxer]

So people running the upgraded heater with stock wiring aren't blowing fuses? Appreciate it.

 

[lonesouth]

I suspect mine is blown. Hasn't worked in a while, but I haven't looked into it yet.

 

[DirtDonk]

Wanted to install this mod, but how is everyone running this heater if normal operation is 20-22 amps and our stock heater fuse is 20 amps?
20-22 amps can be found in the "Questions and Answers" area.

So people running the upgraded heater with stock wiring aren't blowing fuses? Appreciate it.

Yes. In fact the subject of blown fuses, or needing a heavier one hardly ever comes up that I remember. Maybe I've just glossed over them and don't remember, but it seems to rarely be an issue.

What we don't know of course is how many of those fuse panels already had a 30 amp fuse, how many installers automatically upgraded without mentioning it here, or how many actually did not have an issue with 20 amp fuses.

But the bottom line is that yes, many of the full-size trucks that these motors might come from actually do use a 30 and even 35 amp fuses in the heater/AC motor circuit. Even though our Broncos might have smaller wiring (I think it's the same gauge though) I don't think a 30 amp fuse is going to be in the dangerous category unless your wiring is compromised. With new wiring, a higher amp fuse is likely very safe.
I have a hard time saying that, because just throwing a bigger fuse at a problem is a problem itself sometimes. I just think that we're ok here with that bump.

So try a 25 amp fuse for starters. If it does not blow, then you know that it's not a short-circuit, but just a higher draw motor pulling too much through an under-rated fuse.
mpboxer, is your wiring original? If so make sure that your fuse contacts are clean and rust-free. Same for any connections you come across and make sure the grounding is good. Otherwise you get a falsely high amperage draw (especially upon initial startup) due to the high resistance of the connections. If you are clean and tight, try a 25 amp fuse to see if that solves any issues.
Or just try the stock 20 and see how yours works. You can't hurt anything but the fuse that way. And those are cheap enough still.

Your nose knows, and so do your eyes. If you're not sure about the general condition of things, keep an eye and a nose peeled around the motor and switch to watch for smoke. That's never a bad idea anyway, but I doubt you're going to ever see it on good wiring and connections. That 22 amps is just not that much. And at only 2 amps above the stock fuse rating, is nowhere near the limit of that circuit's wiring and connections. Fuses are sized below that capacity for protection.

Paul

 

[mpboxer]

Yes. In fact the subject of blown fuses..

Yes, I have stock wiring that's in really good shape actually. New grounds to motor and body as well. Maybe I'll opt for the motor and wait on the cage to see how it runs. That way I'm not cutting away at the housing and can always go back to stock if need be. I'll try the 25 or 30 amp fuse if need be with caution too. Thanks again Paul!

 

[sprdv1]

Yes, I have stock wiring that's in really good shape actually. New grounds to motor and body as well. Maybe I'll opt for the motor and wait on the cage to see how it runs. That way I'm not cutting away at the housing and can always go back to stock if need be. I'll try the 25 or 30 amp fuse if need be with caution too. Thanks again Paul!

Good luck.. Always the little things..

 

[OX1]

Didn't read all 28 pages, but was the 78 Chebbie vs the 92 F250 blower motor/cage comparison ever discussed. Always rather use ford parts when I can.

http://broncozone.com/topic/18919-early-bronco-heater-upgrade/

 

[surfer-b]

Yes, I have stock wiring that's in really good shape actually. New grounds to motor and body as well. Maybe I'll opt for the motor and wait on the cage to see how it runs. That way I'm not cutting away at the housing and can always go back to stock if need be. I'll try the 25 or 30 amp fuse if need be with caution too. Thanks again Paul!

I havnt read all the posts on this but if it hasn't already been mentioned I always add a relay for the heater motor, this way it want be using the stock harness to power the motor, this will take a lot of load off the stock wiring. The heater switch is only used to activate the relay, just add the relay before the resistor harness so will still retain the 2 speed adjustment and add an inline fuse for the relay.

 

[sprdv1]

I suspect mine is blown. Hasn't worked in a while, but I haven't looked into it yet.

That time of year to make sure it works

 

[1strodeo]

That time of year to make sure it works

Or, depending where you live, time to park it! They’ve been itching to salt the roads here in Dayton and it hasn’t gotten below 35

 

[mpboxer]

Did the upgrade today. Huge improvement. I originally wanted to use the new motor and existing cage, so I didn't have to cut the heater box but the old cage doesn't fit with the new motor (it's about 1/2" taller). New cage and new motor fit with about 1/4" trimming on the box.

I tested it for awhile on high with lights and blinker on trying to overload the system and 20amp heater fuse. Fuse got hot, but did not burn out. I picked up some 25amp fuses just in case too. I love this site and thank you for everyone's help and tips!

I used Advanced Auto/Carquest $32:
35587 Motor
35602 Cage

 

[DirtDonk]

Hey good news mp! Glad it's working.
Was the fuse too hot to touch? Or just "hot" and not ready to melt?
Heat is often the enemy of electrical stuff for all the problems that it can cause. Resistance is just one. As it heats up it gets less efficient at flowing electricity so your fan speed suffers, and heat builds up.
Maybe keep that extra 25amp fuse handy just in case...

But more than just handling a higher load, it would not hurt to find out if other things are getting hot too. If the wire stays cool you're in good shape. But keep an eye on the fuse panel.

More work, but if the heat ever becomes a problem, the relay idea surfer-b posted up would be the permanent cure.

Didn't read all 28 pages, but was the 78 Chebbie vs the 92 F250 blower motor/cage comparison ever discussed. Always rather use ford parts when I can.

Good question. I know it's come up many times, but I don't remember anyone ever mentioning that they did both, or had two Broncos side-by-side where they could be compared.
That would be a very interesting thread.
I don't have a problem with the Chevy part, especially as a long used tried-and-true fix. But if I can use a Ford part that's just as good, I like that idea even more.

I haven't read all the posts on this but if it hasn't already been mentioned I always add a relay for the heater motor, this way it want be using the stock harness to power the motor, this will take a lot of load off the stock wiring.

That's been the savior of many an old wiring harness.

The heater switch is only used to activate the relay, just add the relay before the resistor harness so will still retain the 2 speed adjustment and add an inline fuse for the relay.

You mean put it before the switch?
I've used a single one in the high speed circuit after the switch, but could see using two after the switch too. One for high and one for low. I don't think I've used one before the switch before. But that would certainly simplify things.
Would not take any load off the switch itself, but the switch is not usually the problem anyway. And it would still take the load off of the rest of the stock wiring and fuses and associated contacts.

Or are you talking about just the high-speed side getting a relay?

Paul