760 Heater fan

  • Thread starter Thread starter blurp
  • Start date Start date
No fuse? That can get interesting! I would suggest either putting an
inline fuse close to the battery or purchasing a fire extinguisher.



blurp said:
I think I have a cheap and easy solution to this problem...

I bought good 12 gauge automotive wire, some crimp-on ends, and a
switch (not an automotive switch but a heavier toggle rated for 1.5HP
motor use and 20A). My plan is to run a wire from the battery stright
through the firewall to the switch and then to the fan motor and back
again. Since I have tested the fan motor before I can't see why this
won't work. The only thing I'm not certain of is if the 120V switch
will add too much resistance to the 12V line even when open.

Any reason (besides risk of a dead battery if I forget to shut it off)
why I shouldn't do this? Anything I should be thinking of adding to
this simple circuit?

Thanks,
blurp
Click to expand...

__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"
 
Well I have a fire extinguisher but I prefer not to use it (LOL).

The system as a whole normally uses a 30A fuse, with the fan isolated
perhaps a 20A would do? As I understand it the fuse doesn't really
regulate anything, it just blows if the power spikes... so should I
expect to be changing fuses all the time?

I noticed the short stub of wire that runs from the fan to the system
wiring has a fat spot... inline fuse? Some sort of thermal switch? if
I incorporate this short wire in the circuit (rather than go straight
to the fan) will I be covering this?

IS IT POSSIBLE THAT THE WHOLE PROBLEM HAS BEEN CAUSED BY THIS SHORT
STUB OF WIRE WITH ASSOCIATED FAT SPOT? If that is the case I'll laugh
'till cry.

blurp
 
blurp said:
I think I have a cheap and easy solution to this problem...

I bought good 12 gauge automotive wire, some crimp-on ends, and a
switch (not an automotive switch but a heavier toggle rated for 1.5HP
motor use and 20A). My plan is to run a wire from the battery stright
through the firewall to the switch and then to the fan motor and back
again. Since I have tested the fan motor before I can't see why this
won't work. The only thing I'm not certain of is if the 120V switch
will add too much resistance to the 12V line even when open.

Any reason (besides risk of a dead battery if I forget to shut it off)
why I shouldn't do this? Anything I should be thinking of adding to
this simple circuit?

Thanks,
blurp
Click to expand...


Don't go to the battery, go to the fuse box so it's protected and so the fan
shuts off when the ignition is off.

Really though something is still broken, while that hack will probably get
you by, it'd drive me nuts knowing there's still some simple problem
preventing it from working as designed.
 
blurp said:
Well I have a fire extinguisher but I prefer not to use it (LOL).

The system as a whole normally uses a 30A fuse, with the fan isolated
perhaps a 20A would do? As I understand it the fuse doesn't really
regulate anything, it just blows if the power spikes... so should I
expect to be changing fuses all the time?
Click to expand...


No the fuse blows if something shorts out, not having a fuse is very
dangerous, particularly with the amount of amperage a car battery can
develope, your nice heavy wire will heat red hot in an instant and the
insulation will burst into flames if you manage to short it without a fuse,
I've seen cars reduced to a burned out shell because of botched wiring,
mostly for stereo installs.
 
Duly noted and thanks for the advice! I have followed your advice
(partially) and have installed an in-line 30A fuse into the circuit. I
have also retained the wire connector original to the fan with its own
mysterious bulge, suspecting that it too has either a fuse or a
thermal safety of some kind in it.

Running to the actual fusebox adds more complication than I have time
to deal with so I'm hoping the fuse I put in will do the trick.

Here is the diagram representing exactly what I have done:
http://home.eol.ca/~clubshub/760circuit.jpg

I ran out of time before I could test it so several parts have been
left disconnected.

Do have anything obviously backwards?

I'd love to know before I finalize and throw the switch.

Thanks,
blurp
 
blurp said:
Duly noted and thanks for the advice! I have followed your advice
(partially) and have installed an in-line 30A fuse into the circuit. I
have also retained the wire connector original to the fan with its own
mysterious bulge, suspecting that it too has either a fuse or a
thermal safety of some kind in it.

Running to the actual fusebox adds more complication than I have time
to deal with so I'm hoping the fuse I put in will do the trick.

Here is the diagram representing exactly what I have done:
http://home.eol.ca/~clubshub/760circuit.jpg

I ran out of time before I could test it so several parts have been
left disconnected.

Do have anything obviously backwards?

I'd love to know before I finalize and throw the switch.

Thanks,
blurp
Click to expand...


You want the fuse to be on the positive side, not on ground. If the positive
side is factory wiring then it's already fused in the fuse box.
 
blurp said:
("Why won't that guy with the heater fan problem just go away?")

Hi all,

The heater fan mystery persists. Over the weekend I examined the
diagrams associated with the Power Stage unit and tried to eliminate
the relays entirely by pulling the incoming wire and connecting it
where the outgoing wire should go at the fan itself. For a better
explanation of that please take a look at the bottom of the updated
web page:

http://home.eol.ca/~clubshub/
Click to expand...

I've looked at that, that should have worked, giving you full blast fan.
See below.
So all of this is based on my interpretation of the diagrams (also
detailed on the web page) and I don't know if I'm thinking right. If I
am then I believe I have just eliminated the Power Stage as a point of
error.

This leaves only the dashboard controller as a suspect. If I cannot
rely on my results based on eliminating the Power Stage please let me
know.

Thanks very much,
blurp
Click to expand...

This pin 7 is connected in some way with the vehicle lighting, but, I'm
not entirely sure what it does, or why.

You need to carry out some more basic tests, testing not just for
presence or not of 12volts, but also for presence of ground (negative).

Check the following, derived my studies of the Haynes manual:-
1. Continuity of the blue/black wire from the motors negative terminal
to its other end at terminal 1a on the power stage.
2. Presence of ground on the black wire connected to terminal 2a of the
power stage.
3. Presence of 12volts on the violet wire connected to terminal 1 of the
power stage, at all times.

Caution: If you short (as you suggest on the website) terminals 1 and
2a, you will blow fuse 28

4. Presence of ground on black wires connected to terminals 3 and 4 of
the ECC ECU.
5. 12volts on pin 21 (violet) of the ECC ECU, at all times.
6. 12 ish volts on pin 20 (red) when the engine is actually running
(this wire connects to the battery warning lamp, and presumably tells
the ECU that the engine is running).
7. 12volts on the orange wires connected to pins 1 and 2 of the ECC ECU
when the ignition is switched on.

I gather you have done some of the above, but do check the rest, as
grounds are just as important as supplies, and that little trick you
did, of effectively bridging 1a and 2a on the power stage, should have
given you full speed fan, even with the car switched off; this suggests
you have a failed ground connection somewhere.

Hope this helps and makes sense.

Best wishes from the UK, Ken Phillips
 
I don't know if I should feel triumphant or foolish.

I wired the system up as described and the fan turned so I shut it
off. Then it wouldn't go again. I checked over my wiring and it still
wouldn't go, double-checked all the connections, the fuse, the battery
and still no dice.

So I removed the fan (again) and flipped the switch and still nothing.
THEN I TOUCHED THE FAN BLADE ever so gently and it roared to life! So
I shut it off and let it spin down and flipped the switch again and
again it just sat there until I gave it a little nudge to get going
and it took off again.

Emboldened I reconnected the power stage I had suspected was faulty
and started the car. I turned the control to 1 and nothing
happened...until I gave the fan a little help and then it all worked
fine, cycling through the various speeds until I shut it off again.

When I originally checked the motor (August 27th!) I had held it in my
hand and, by doing so, must have given it the little bit of motion it
needed to get going.

So there you have it... the first suspect is back on the top of the
list! I am now calling around to source out a fan and replace the
damned thing and get on with my life.

Barring any surprises (fingers crossed) this should be wrapped up.

A million thanks to all who looked at these long-winded posts and who
indulged all of my ignorance and taught me how this system works, sent
me diagrams, and critiqued my assumptions and trains of thought.

And although I gritted my teeth and cursed a lot, I really enjoy doing
this.
 
Well done Blurp! The fan problem could just be due to the brushes having
worn to the point of sticking in their holders or just plain stuck or worn
out. Try the GM blower (I think it is a direct replacement). Mike F may be
able to verify that.

All the best, Peter.

700/900/90 Register Keeper,
Volvo Owners Club (UK).
 
blurp said:
I don't know if I should feel triumphant or foolish.

I wired the system up as described and the fan turned so I shut it
off. Then it wouldn't go again. I checked over my wiring and it still
wouldn't go, double-checked all the connections, the fuse, the battery
and still no dice.

So I removed the fan (again) and flipped the switch and still nothing.
THEN I TOUCHED THE FAN BLADE ever so gently and it roared to life! So
I shut it off and let it spin down and flipped the switch again and
again it just sat there until I gave it a little nudge to get going
and it took off again.

Emboldened I reconnected the power stage I had suspected was faulty
and started the car. I turned the control to 1 and nothing
happened...until I gave the fan a little help and then it all worked
fine, cycling through the various speeds until I shut it off again.

When I originally checked the motor (August 27th!) I had held it in my
hand and, by doing so, must have given it the little bit of motion it
needed to get going.

So there you have it... the first suspect is back on the top of the
list! I am now calling around to source out a fan and replace the
damned thing and get on with my life.

Barring any surprises (fingers crossed) this should be wrapped up.

A million thanks to all who looked at these long-winded posts and who
indulged all of my ignorance and taught me how this system works, sent
me diagrams, and critiqued my assumptions and trains of thought.

And although I gritted my teeth and cursed a lot, I really enjoy doing
this.
Click to expand...

This is the older style that mounts vertically in the footwell over by the
ECU right? If that's the case, just go to your local autoparts store and buy
a fan for an '87 Chevy Celebrity or Citation, it's the *exact* same AC-Delco
part and it's under 20 bucks.
 
blurp said:
I don't know if I should feel triumphant or foolish.

I wired the system up as described and the fan turned so I shut it
off. Then it wouldn't go again. I checked over my wiring and it still
wouldn't go, double-checked all the connections, the fuse, the battery
and still no dice.

So I removed the fan (again) and flipped the switch and still nothing.
THEN I TOUCHED THE FAN BLADE ever so gently and it roared to life! So
I shut it off and let it spin down and flipped the switch again and
again it just sat there until I gave it a little nudge to get going
and it took off again.

Emboldened I reconnected the power stage I had suspected was faulty
and started the car. I turned the control to 1 and nothing
happened...until I gave the fan a little help and then it all worked
fine, cycling through the various speeds until I shut it off again.

When I originally checked the motor (August 27th!) I had held it in my
hand and, by doing so, must have given it the little bit of motion it
needed to get going.

So there you have it... the first suspect is back on the top of the
list! I am now calling around to source out a fan and replace the
damned thing and get on with my life.

Barring any surprises (fingers crossed) this should be wrapped up.

A million thanks to all who looked at these long-winded posts and who
indulged all of my ignorance and taught me how this system works, sent
me diagrams, and critiqued my assumptions and trains of thought.

And although I gritted my teeth and cursed a lot, I really enjoy doing
this.
Click to expand...
Thanks a zillion for the feedback. Dead spots in the motor aren't normally
the first thing we think about, so they can bite us hard!

Mike
 
This is the older style that mounts vertically in the footwell over by the
ECU right? If that's the case, just go to your local autoparts store and
buy
a fan for an '87 Chevy Celebrity or Citation, it's the *exact* same
AC-Delco
part and it's under 20 bucks.
Click to expand...
In fact, the last time I bought one I decided to splurge on the Genuine
Volvo part. But the Volvo part (besides being around $150 US) required
metalwork of the mount area in the car to fit! I returned it and bought the
GM fan, which works nicely, thank you.

Mike
 
Apparently there are two common kinds of blower motors for 7xx Volvos,
primarily differentiated by their electrical connector types: one- and
two- pronged. I need the kind with 2 prongs on the connector and which
mounts horizontally (with the axle pointed toward the front) and with
a vaguely triangular flange/base.

I called the Volvo dealership and they wanted $300 for a new one. I
called CanTire and they claimed to have one but when I got there and
visally inspected the part (at a sweet $75) it was the wrong kind.

The old blower has Delco stamped on it but (you'll love this) the
Delco parts dealer my brother-in-law contacted said that he cannot get
that part, it goes direct to dealer.

So knowing there is an equivalent part out there for another car is
reassuring, now I just need to find the part listed with a photo so I
can visually compare and determine the exact part number. I suspect
all the part numbers listed on the old motor are Volvo numbers.

If I can find a pic of the 87 Citation or Celebrity fan I'll be able
to determine if it's a match. Failing that I may go into a Chevy
Dealership and let them scratch their heads over it for a bit.

Thanks again for your suggestions, if this info helps you nail down
the exact part I want please let me know.

Thanks,
blurp
 
Well I've ordered it so, for the first time ever, I hope you're wrong
:)

I went to the Chevy dealership last night and got the blower fan for
Cavalier and years listed but the part has changed: Insead of having
the bare-metal top it had the plastic cowl built in and, although it
ran properly when connected and the mounting holes were in the righ
places, the built-in cowl meant that I couldn't use the Volvo cover
for the motor and that left holes in the system.

So hopefully when this thing arrives I'll be able to fit the Volvo
cover over it. Failing that I'll just cover the holes with silver duct
tape.

I'll let you know, should be here before the weekend.

Cheers!
blurp
ps. in comparing my home computer to this work computer I have found
that some messages aren't coming through at work. To those whose posts
I haven't addressed I apologize (especially Ken, whose feedback about
the diagrams and assumptions on the website would have been invaluable
had I seen them earlier!)
 
The fan arrived via UPS this morning and I took it over to the car at
lunch, dropped it in, connected the power and put the screws through
the mounts and fastened the blower and the plastic cowling, started
the car, crosssed my fingers, and cranked the fan speed dial to 5...
it worked!

Ah the sweet smell of victory, blown through the ductwork of an '88
Volvo 760.

Again, I give my thanks to all who helped out with suggestions etc.
and will be happy to help you troubleshoot your own heater system
problems in the future now that I have all of this new knowledge :)

Cheers,
blurp
 
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