Heat Booster Fan

[memphis]

Hi All!

Is there a way that I can test the heat booster fan? I am in the process of taking the dash switch out for testing, but would like to know if there is a way to test the fan without the switch? This way I know at least the fan itself is working.
Thanks in advance for your help and advice.
Bob

 

[Randy Forbes]

You could put the two (2) wires together (from the harness) that connect to the switch...

 

[memphis]

Thanks Randy!

Obviously I am not an electrician, but I guess this would complete the circuit and run the fan :confuse: .

This is my first British car and first car with a positive ground system. I am not yet comfortable with this system.

Looking forward to the day that the light clicks on and I'm "in the zone". I guess I just need to keep working on her.

Many Thanks!
Bob

 

[Bob_Spidell]

... This is my first British car and first car with a positive ground system. I am not yet comfortable with this system. ...

It may help to think in terms of 'common' instead of 'ground' (most cars are electrically isolated from the ground by the tires, except a few I've seen with a metal strap which drags the ground, I guess to dissipate static electricity). Common is simply a convenient way to complete the circuit to the battery using the metal chassis (otherwise, you'd need two wires to every electrical component).

Negative 'ground' and positive 'ground' behave no differently--the electrons flow in the same direction regardless of which battery terminal is connected to the chassis. The main issue is that most modern electrical devices--e.g. GPSes--are wired for negative ground (common), so you can't just plug them into the power circuit on your Healey (unless they are isolated, and possibly have the leads reversed). There are several discussions on this forum on how to do this.

 

[Rob Glasgow]

Speaking of heater booster fans, somewhere I heard that the fan motor used in the Datsun 240Z was a clone of the Smiths fan used in our Healeys. I've seen photos of the Datsun blower motor and they do look similar. Because they were build in the mid 70's, they may have been multi-speed, but I don't know for sure.
Question - (1) Anyone know if the Datsun motor will fit the Smith fan case relatively easily? (2) Anyone ever install one on their Healey and what do you think? (3) Is the Datsun fan multi-speed?

Answers to any of the questions would be appreciated.

 

[red57]

Rob,
I have been using a 240z fan in mine for 20 years or so. Wasn't a big plan to do but one day my fan died and I am cheap and I had a dead 240z out back and.......

I don't know if the guts could be put in in a Smiths case or not. I just used the complete 240 fan. Don't remember all the details, but I just bolted it in the same location as stock. The only 'modification' needed is to the output side of the fan - the 240 has a square outlet and I had to make a small sheetmental adapter to go from the square to round to accept the Healey round duct. The inlet side of the fan is round and the right size for the Healey duct.

When in place the inlet and outlet are pointing the right directions to fit the Healey ducts.

Don't know if they can be run as multi-speed, I just have an on/off switch.

Blows a lot more air then the Smiths fan did, and has been very reliable.

You will need a relay if you want to use the stock fan (boost) switch - I'm guessing it draws more current because it cooked my stock switch quickly. I mounted a heavy duty toggle switch but a relay and the stock switch would be better I think.

I really like it - it actually demists!! Don't have a way to measure it but it sure feels like a lot more air is moving. And it was free.

Dave

 

[memphis]

Hi Guys!

I tested the fan by connecting the wires together at the switch.
No luck....

Is the fan 12 volt? Can I test the fan, at the fan. The fan has one wire connected to the chassis (common). The other wire is connected to a green/yellow wire that goes into the main harness.

Can I simply find a power source in the engine compartment and test the fan? Any suggestions on where I can find a 12 volt source in the engine compartment?

I do see a brown wire connected at the starter. Use that one?

Thanks!
Bob

 

[57_BN4]

Hi Bob,

Try connecting a test-light or a park light bulb between the fan supply wire and a clean earth with the ignition and fan switch on.

Light = power = probably a burned out motor.

I got a box of spares with my BN4 and in there is a fan motor that looks like it has caught fire inside. If you need a replacement motor I'd be 99% sure it will be common to a heap of vehicles around the era. Pretty sure it is the same as Ford Zephyr.

If testing the motor, be a little careful using the starter cable as a test power source, it is unfused and if your test wire touches the chassis many bad things can happen.

Andy.

 

[Johnny]

Hi Bob, do you have a shop manual for the Healey? If so go to the NNN section and look at how the fan is wired. Pretty simple stuff actually. Most likely you have a loose connection somewhere or the fan has seized up. You need a volt-ohm-meter or test light of some sorts to check if voltage is getting to the fan motor.

Good luck at finding your problem, and please let us know what you found, no matter how simple.

 

[memphis]

Thanks Guys!

I turned on the fan switch and with a test light: one end connected to the chassis and the other to the main fan wire in the engine bay, the test light lights up!

So it is getting power. Bad news, its a defective fan.

It looks fairly easy to replace, correct?

Thanks!
Bob

 

[AUSMHLY]

Bob, is your car positive or negative?

 

[tahoe healey]

I spent over 3 hours connecting the black tubes so it ain't that easy.

 

[memphis]

Hi Roger,

My car is positive ground (common).
Bob

 

[memphis]

Success! Got the blower working this morning. Turns out it was a rusty female socket on the fan wiring itself. When I tested with my test light, I tested the male (wire harness) end and always got power. Tested the female end (fan wire) this morning and no power. Cleaned the female socket, connected and got power, but fan still didnt spin up. Took rubber hammer and tapped on the fan, and whala... fan works!
Bob

 

[John Turney]

Maybe a bit of oil on the bearings would be called for.

 

[richberman]

Sounds like the hammer is a good tool to carry in the boot. It works on the SU fuel pump too :wink:
rich

 

[Johnny]

Hi Bob, the green wire can be touched any 12V terminal and you should be able to hear the fan run. That green wire runs to your switch by the way, then the other side of the switch (probably another green wire) goes to the green fuse on the firewall. It's common to have all those green wires separate at the fuse. Also it's possible a wire came loose at the switch.

Good Luck, let us know what you found to fix the problem.

 

[memphis]

Hi Johnny,

The old fan ran for a short while, then locked up. I guess old age...

I ended up replacing the fan motor inside the housing.

All works great now.

Thanks,
Bob