Printable Version of Topic

Posted by: Trav012000 Oct 25 2008, 02:58 PM

I figured the word naked would get some more hits.

Anyway, I've got a link here to a picture of my relay board. Now I've been racking my brain for the past week or so trying to track down the problem that's causing my heater fan not to work (as its going to get cold here in the next week or so). Now if I'm reading diagrams correctly, then my relay board is missing a relay for the heater fan. Take a look and let me know if I'm right. I don't need the relay for the rear window defogger, but how about the other relays, should my car not be running?

I've got a 76 that the previous owner converted to dual webbers. Other parts that are kind of important that currently don't work are horn and fresh air blower. Am I lucky enough to just be missing the relay for all three? (I've not actively sought to fix them just yet)

http://fultonglass.com/relay.JPG

Thanks for the help.

Posted by: Gint Oct 25 2008, 04:25 PM

Beats me off the top of my head. My heater fan doesn't work either. Don't really need it though. They're pretty weak.

This Pelican link might help you out. http://www.pelicanparts.com/914/914_electrical_diagrams.htm

And just so this post isn't all negative, here's your picture.


Attached thumbnail(s)

Posted by: Trav012000 Oct 25 2008, 04:36 PM

Thanks.

I'm not needing it for the heat, as much as the defrost.

Posted by: southernmost914 Oct 25 2008, 04:38 PM

You have carbs and your fuel pump has been rewired. Your ok to a point. The rear missing relay is your blower motor.

Steve

Posted by: Gint Oct 25 2008, 04:42 PM

The fan only does any real good at dle speeds. Anything above that and the engine cooling fan starts to overcome anything that the heater blower motor puts out. We just had a thread about this a month or two ago. I know where you're coming from though. It's colder for you in the winter than it is for me. If I could fix mine easily enough I would. Not a real priority for me though. But let us know when you figure it out.

Posted by: Trav012000 Oct 25 2008, 05:05 PM

Just saw this on Pelican Parts faq:

"...Also be aware that the heater blower motor and the fuel pump share the same fuse on the relay board in the engine compartment. It is not uncommon to have a 914 that dies from lack of fuel when you pull the heater blower switch due to a short in the system."

I guess I can just get one relay in, plug it in at various places and see what parts on my car start working. lol

Posted by: southernmost914 Oct 25 2008, 05:08 PM

Maybe you did not notice and I hate to quote my self but..........

Steve

Posted by: Trav012000 Oct 25 2008, 05:21 PM

Yeah sorry I did notice, in fact after I saw your post and it confirmed my suspicions I went ahead and ordered a relay.

I just realized in that quote it said fuse, while I read relay.

What I meant by "just plugging in" was my horn and my fresh air blower also dont work. I'm hoping its as simple as replacing those relays, so once I get my one good one in I can test it in those two other spots to see if the relays have gone bad.

Posted by: southernmost914 Oct 25 2008, 05:40 PM

You can pull the ones out from under the dash and use them to test.. just an idea.

Steve

Posted by: bperry Oct 25 2008, 08:24 PM

Below is a photo of a relay board with some markings to help out in the discussion.
I'll reference the picture below.



Ok, so you can see what each relay is used for.

First notice the pink and green circles on the heater fan relay socket.
Notice the cyan circle on the T14 connector at the top.
Then also notice the orange circle on the T12 connector lower right.

The heater fan (and the fuel pump in stock configuration) is powered
by the red fuse in the photo above.

This fuse is hot all the time even when the ignitiion is off.
This fuse is directly connected to pin 30 of the heater fan relay which is
the pink circle.
Pin 9 on T14 (cyan circle) is connected to a green/white wire that goes
to a switch that grounds when the heater lever is pulled.
When the heater relay engages, it connects pin 30 (pink circle) to pin 87 (green circle)
Pin 87 (green circle) is connected directly to pin 11 on T12 (orange circle).
Pin 11 on T12 is attached to a green wire that should run to the heater blower fan.

So using this information you can track down where you problem is.
You won't need a partner for most of this and you won't need any spare
relays to guess with for most of this as well.

0) check to make sure that the heater blower fan is connected and that the
green wire connects to Pin 11 on T12 (green circle) in picture above.
Remove the heater blower relay if there is one plugged in.

1) Check for voltage between the pink circle and ground.
The ignition does not have to be on.
The battery should be close enough to actually use the (-) terminal for a ground.
If you see 12v this is very good.
If not goto 4)

2) short/connect pins 30 (pink) & 87 (green).
This will turn on voltage to pin 11 on T12 (green circle).
If the wires are good to the blower fan and fan is good it should turn on.
If not there is a problem with either the wires from the T12 connector
to the fan or the fan itself.


3) plug in relay and test full circuit
Turn on ignition and then pull the heater lever.
The heater blower fan should turn on.
If not there is a problem between the heater fan switch
and the relay board or you have a bad relay.

If you have a partner have them flip the heater blower switch
while you feel the relay. If you feel the relay "click", then the
relay is bad. Try another relay. If you don't feel a "click",
then the issue is in the heater fan switch wiring or the switch
itself.

The heater fan switch connects to the relay board on pin 9
on T14 (cyan circle) via a green/white wire.


--------------------------------------------

4) Check voltage on right side of red fuse.
If you see voltage here but not on pin 30,
you have something loose in your relay board.

5) Check voltage left side of red fuse.
If no voltage here. Fuse is bad.

---------------------------------------------


While not a complete diagnostic chart. It should help narrow
the problem down.

---- bill

Posted by: southernmost914 Oct 25 2008, 09:04 PM

Copy & Print
Steve

Posted by: Trav012000 Oct 28 2008, 03:27 PM

Awesome, that'll definitely help.

On another note, you say that if you try to engage the heater, and you hear the relay click, then it's bad. I take it this is for all relays. Reason I ask is when I try to honk my horn, all I get is a click. Don't know if it's the switch in the horn or the relay though so I'll be sure to pay more attention next time.

Thanks for your help everyone.

Posted by: southernmost914 Oct 28 2008, 03:47 PM

If you hear the relay click the steering collum switch is fine. Check power to the horn, if no power swap a relay. Horns fail and don't last forever.

Steve

Posted by: warrenoliver Oct 28 2008, 04:10 PM

I have tried it both ways and I can tell you that the heater blower motor does help (a lot), once the temps get below 20 degrees! Stays pretty damn cold in the 914 when the blower motor doesn't work. When it does work, it gets pretty toasty.

As far as the horn and the fresh air blower, when my ignition switch started to fail, I also lost power to the horn and the blower motor - also to everything else eventually! Once I replaced the defective ignition switch all kinds of things started working correctly.

Warrenoliver

Posted by: trherald Oct 29 2008, 09:09 AM

I had a similar issue with my 914 when I first got it in July, and the problem ultimately seemed to have several sources:

1. The fan wasn't even connected! Once it was connected, it still didn't work.

2. The relay was in place, but always seemed to be activating, even when it shouldn't. This was eventually tracked down to a short in one of the traces on the relay board - replacing the board solved this problem.

3. The main power feed on the large connector (top of relay board) was loose and not contacting the pin properly. This is a tough one to solve because you can't buy either the connector or the pin......

4. The switch on the heater control inside the car wasn't connected. After a few hours tracing wires and testing continuity, as well as cleaning the switch, it worked fine.

As you can tell, most of the time was spent with a multimeter tracing wires, testing continuity, testing relays, etc. Time consuming, but not difficult.

After all that, the blower motor now works - at least as well as it ever did.

Posted by: stepuptotheMike Oct 30 2008, 04:11 PM

Totally awesome. I just fixed my blower motor thanks to this little ditty. PO had it connected to a whole different set of Green/Brown wires. 2 minutes and I had the thing running again.

Thanks Bill!!!

-Mike