760 Heater fan

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

On Tue, 27 Sep 2005 00:24:43 -0400, the illustrious blurp favored us with the following prose:

Reply to
blurp
Loading thread data ...

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

blurp wrote:

__ __ Randy & \ \/ /alerie's \__/olvos '90 245 Estate - '93 965 Estate "Shelby" & "Kate"

Reply to
Randy G.

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

On Thu, 29 Sep 2005 08:16:46 -0700, the illustrious "Randy G." favored us with the following prose:

Reply to
blurp

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.

Reply to
James Sweet

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.

Reply to
James Sweet

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:

formatting link
ran out of time before I could test it so several parts have beenleft disconnected.

Do have anything obviously backwards?

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

Thanks, blurp

On Thu, 29 Sep 2005 17:39:17 GMT, the illustrious "James Sweet" favored us with the following prose:

Reply to
blurp

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.

Reply to
James Sweet

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

  1. Presence of ground on black wires connected to terminals 3 and 4 of the ECC ECU.

  1. 12volts on pin 21 (violet) of the ECC ECU, at all times.
  2. 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).
  3. 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

Reply to
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.

Reply to
blurp

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).
Reply to
Peter K L Milnes

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.

Reply to
James Sweet

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

Reply to
Michael Pardee

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

Reply to
Michael Pardee

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

On Fri, 30 Sep 2005 23:18:13 GMT, the illustrious "James Sweet" favored us with the following prose:

Reply to
blurp

OOP! I think I found it!

formatting link
Blurp

On Mon, 03 Oct 2005 11:34:15 -0400, the illustrious blurp favored us with the following prose:

Reply to
blurp

That looks very similar, not quite the same though. Don't you have any autoparts chains? I would think there'd be something similar to Schucks/Kragen, Pep Boys, that kinda thing around and they should have the motors.

Reply to
James Sweet

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!)

On Tue, 04 Oct 2005 02:23:07 GMT, the illustrious "James Sweet" favored us with the following prose:

Reply to
blurp

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

Reply to
blurp

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.