MacTrader

Hi Guys
Just joined, don't know what took so long.
The blower motor ground on my 73 convertible w/air has gone away.
I have the wiring diagram, but I can't figure out where the ground wire goes once in the harness. It must attach to the frame or electrical block somewhere.
Should I chase this down, or just add an extra ground wire from the blower motor to a good ground?
Thanks in advance
Mac

TimAT

Check around the starter area- the (out on a limb here, not 100% sure about 73) C3's used a black wire that came out of the starter harness area for a ground for both the wiper motor and blower motor. It's supposed to be attached to a bell housing bolt

Peterbuilt

Hi and welcome.
The original BLACK ground wire for the wiper and fan connects to a bell housing bolt down by the starter.

https://docs.google.com/viewer?a=v&p...ZTM0ZDc1MWM5Ng

MacTrader

Thank You Guys
I really appreciate that info.
The ground is still making contact, but not good contact. Blower fan runs very slow
Will get it up in the air tomorrow and correct this.
Thanks again
Mac

Peterbuilt

If you apply 12 volts to the fan input does it go faster?

Tell us about the switch positions and what happens at each selection.

MacTrader

I only have to ground the blower flange ( where the mounting screws are ) to get the blower up to full speed. Otherwise it spins verrry slow.

I disassembled the high speed relay and it is working fine.

Might still have problems with the slower settings, I haven't tried them.

Those blowers aren't that powerful and I run it on " High " almost all the time anyway.

Thanks for your input
Mac

Peterbuilt

If you leave the NEW ground wire connected do all the speeds work properly?

mrvette

Several things, That black ground wire is frequently attached in error to the Batt terminal on the solenoid.....it does go go ground, and on MY car it goes to the intake manifold, but my car is custom...and I used very heavy wire so no voltage drop, second off is to pull the fan motor, and get a dirt sucker hose into the resulting hole, I cut the fender liner out on my car, so able to put it back again....this allowed access to the motor and also get the hose down into the evaporator coil and suck the damn leaves/dirt out of the housing.....be amazed how much crap is in there....

AND replace the entire fan/squirrel cage with a C4 blower assy, much stronger air flow.....another thing, pull the outside air door, disable the shut/open mechanism, and seal the damn door shut with RTV.....and on the inside, take the door out and toss it, behind the pass side kick panel....block the vacuum control line.....so the system is on permanent recirculate....and no more leaves to contend with.....

and with the C4 blower assy, it will freeze the nutz off king kong.....

pigfarmer

I did an a/c delete and I think the ground wire originally may have been shared with the wiper motor with a goofy little double connector. Failures are almost always at connectors. Mine were mostly melted.

I had to make my own harness wiring for the relay and resistor - the original sections were cooked. I just ran a #12 black wire to the underside of the frame right under where the condenser used to be. There was already a conveniently threaded hole right there with nothing in it. It's out of the way and unnoticeable. Blower fan is fine.

MacTrader

Just checked it out and all speeds work properly with a new ground wire
attached to the motor flange.

MacTrader

I haven't been under the car yet to fix that ground wire, prettty sure that will correct the blower function.

My AC is history, the evap is shot. I'm not going to replace it until I have the engine out, and I'm not planning on ever taking it out again.
I did print out your post and will do the C4 assy switch if I ever do the evap replacement
I'm in NY so the top down works for short trips.

Thanks for your input

MacTrader

All of the black wires and connectors seem fine.
My wiring diagram shows several units tied into the same ground in that area.Like the anti-theft hood switch, time delay relay
If I can't locate the problem I'll add a new ground like you did.

Thanks

MacTrader

PROBLEM SOLVED
The black ground wire that exited the starter harness did attach to a bolt in the bell housing. The loom that holds the starter wires also attaches there.
The bolt wasn't tight and the ground wire made poor contact. So simple a fix, but I wouldn't have know where to look without the help of you people here.
THANK YOU