Heater Aux blower, Aux heater blower no workie Options

[sdoolin]

Hooking up the heat on this '73 I just purchased. Never understand why heat is disconnected on street cars. But anyway...

Flapper boxes reconnected and in good condition, cables in good working order and I made a block off plate for the passenger side "riser" (that goes up through the engine tin.

So I have heat to the cabin from the main engine fan, cannot get the aux blower motor to engage. Electrical connections good in engine compartment, so I am hoping it is just disconnected at the switch/lever in the cabin, or perhaps a fuse.

What's the best way to service this lever? I searched on "heat", and a few other keywords but got mostly discussions about SS heat exchangers (which I have). Looking for the fastest way into the tunnel to see if the lever is connected to the harness for the aux fan.

All help appreciated.

[rhodyguy]

unbolt the lever assembly and ensure the wire is on. iirc the lever provides the ground for the fan. while the lever controls the flapper boxes, at the max of the lever travel is when a little nub on the assem makes the contact.

[BeatNavy]

unbolt the lever assembly and ensure the wire is on. iirc the lever provides the ground for the fan. while the lever controls the flapper boxes, at the max of the lever travel is when a little nub on the assem makes the contact.

(IMG:style_emoticons/default/agree.gif) It's probably either the ground wire missing at the lever or a failed relay on the relay board. When you unbolt the lever, pull the assembly gently out of the tunnel a few inches and find the ground wire, if possible. It may have come disconnected and might be dangling in the tunnel (I had to use a small mirror and dental pick to fish mine out). Find/clean that connection.

If it's grounded at the lever, check Relay 55. Swap in a known good one into that and see if that works.

[barefoot]

The heater lever on mine had the electrical contact broken off, so had to get a new lever assembly. Be careful when you pull the lever off !

[sdoolin]

Finally got to inspect the lever (remove seats, backpad, console, carpet, etc). There is a green with white tracer wire nicely connected to the lever, and the "nub" at the far end of lever travel. I'd think a ground wire would be the ubiquitous VW/Porsche brown?

Anyway, will check relay 55 next (gotta find it first).

[BeatNavy]

Yes, but I believe that is in fact the correct wire and color. The relay should be the one furthest back, IIRC. I'll find the link to the relay board diagram on Pelican.

EDIT: Here it is (at least for the '73 - the '71 is also on Pelican): Relay Board.

It's relay 55. That green/white wire is the same one connecting to the 14 (?) pin connector at the front of the relay board on Pin 9, I believe. Through the board it connects to relay 55 at pin 86.

[sdoolin]

Thanks for the link, I believe I have a good spare relay.

[BeatNavy]

If it still doesn't work after swapping out the relay, remove the blower and directly (and carefully) connect 12v to the leads and see if it will run at all. Don't know what kind of shape yours is in, but I had to clean mine pretty well to get it to move.

Good luck.

[sdoolin]

I imagine I will remove it and clean it anyway. I have had to deal with 911 footwell blowers many times, and a good cleaning always gets them spinning freely.

Thanks again.

[sdoolin]

Swapped relay 55 with another relay from my pile of spares (unknown condition). Checked all fuses visually, all OK. Removed blower motor and cleaned (it spun freely). Hooked it up to a 12V power supply on the bench, works just great. Put it all back together, key in "on" position, lever all the way back, no blower motor.

(IMG:style_emoticons/default/headbang.gif)

What am I missing?

[BeatNavy]

Your fan works, so it's a matter of getting it power and ground. Time to check continuity and connections. I would do a couple of things:

1. Did you CLEAN the ground connection at the lever? That's worth doing so you know you do have a good ground (if you did not when you were in there).

2. With ignition on and heater lever in the up position (all the way), use a voltmeter or test light and see if you have power at the green lead on the blower motor (ground the test light/voltmeter to the battery negative post). If you do, then I believe the ground lever, the relay board, the relay, and the other connections are good. Check the actual blower motor ground brown wire to its grounding point (I'm not sure if mine is stock or not -- it's been grounded to a dedicated ground point off the block -- it's effective, but it doesn't look original to me).

3. Most likely, you do not. So your issue is probably somewhere in one of the connections on the relay board or back at the heater lever. Without the ignition on, test continuity from relay pin (the hole) 87 to connector pin 11 on the 14 pin connector at the front of the relay board (if I'm reading the diagram correctly). If you have any doubts about the continuity clean the connection points at the relay, at the 14 pin connector, AND at the 12 pin connector on the rear right side of the board - pins 11 and 10 are the operative ones here I think.

4. Are you actually getting a good ground to the relay? With ignition on and the heater lever in the up position, do you have 12v at pin 87 of the relay? If not, the issue is on the relay board to the 14 pin connector or from there to the grounding point at the lever.

That's pretty much it. This all assumes the relay you used was truly a good relay. Anyone else have any thoughts?

[rhodyguy]

do your headlights work? if so, use one of those relays.

[malcolm2]

Swapped relay 55 with another relay from my pile of spares (unknown condition). Checked all fuses visually, all OK. Removed blower motor and cleaned (it spun freely). Hooked it up to a 12V power supply on the bench, works just great. Put it all back together, key in "on" position, lever all the way back, no blower motor.

(IMG:style_emoticons/default/headbang.gif)

What am I missing?

Broken wire maybe? Take the wire loose from the lever and the fan. check for continuity, end to end of that wire.

If you take the wire off of just the fan, pull the lever to make contact, you could then check continuity from the fan end of the wire to a metal point on the car. That would tell you that it is grounding. and the wire is not broken.

make sure the nub and the little brass springy piece the wire is on at the lever are connecting, and that they are clean.

I would have to dig deeper on the 12v side with the diagram, but you need to go thru all the wiring and connection points for the device that is not working.

Since the fan works on the bench, The problem must be in the car.

Good luck

Edit: cleaning on electrical stuff, can mean a couple things. Clean, like wipe the dirt and grease off is one.

The other would be to SHINE, like with a scotchbrite pad or emery cloth or high grit sand paper or small file. Shine up both sides of a connection.

[sdoolin]

Thanks so much for the responses. While I am comfortable and knowledgeable with engines, brakes, chassis/suspension and "mechanical" stuff in general, wiring has always been "magic" to me.

I'll try all of what y'all have suggested here sometime in the next week (out of town this weekend) and hopefully will find a solution. Will report back.

[BeatNavy]

This is a good electrical challenge then from which to learn. The electrics of the heater blower are pretty straightforward and will help you understand how this stuff works on the 914. If you don't have them already, get a voltmeter (or multimeter) or at least a test light. You'll definitely need them again. Good luck.

[sdoolin]

The other would be to SHINE, like with a scotchbrite pad or emery cloth or high grit sand paper or small file. Shine up both sides of a connection.

Agree - my experience with the VW Bus, Beetle, and countless vintage bikes has tought me to "shine" these connections. Steel wool, Scotchbrite, 400 grit SP, brass brush, even polish sometimes.

This is a good electrical challenge then from which to learn. The electrics of the heater blower are pretty straightforward and will help you understand how this stuff works on the 914. If you don't have them already, get a voltmeter (or multimeter) or at least a test light. You'll definitely need them again. Good luck.

Agree also. I have multimeter and test light. They are in a drawer of the toolbox I use very rarely. Gonna get them both out later today.

[OU8AVW]

I had issues with my headlight motor. I took a long wire and ran it straight from the switch to the motor. It worked telling me the wire was bad. I found the break when I pulled it out to be replaced....

[Spoke]

Try touching the wire on the heater lever directly to chassis to see if the fan turns on.

If you do this with the ignition on (you want to disconnect the red wire from the coil to keep from damaging the points/pertronix/coil while the engine isn't running) you should be able to hear the relay click on.

Also I think there's a fuse on the relay board for the fan. Check the fuse and clean the fuse contacts.

[sdoolin]

Got free of work so went to the barn to check a few things (I have not gotten to ALL of y'alls suggestions)...

Key switched on, lever all the way back. Touch test light to green wire from harness at fan - no light. Touch test light to brown wire from harness at fan - LIGHT! There is a yellow and a brown wire coming from the fan. These have been hooked up as:

Fan Yellow - Harness Green
Fan Brown - Harness Brown

Not sure if this helps me? Apologies for my ignorance (ask me _anything_ about a 76 VW Bus though (except how to troubleshoot aux heater fan))...

[BeatNavy]

I'm trying to wrap my head around this. When using your test light, how are you grounding it? (Where are you connecting the alligator clip of the test light?)