72 Blower Motor INOP
Thread Starter
Racer
Joined: Jun 2009
Posts: 316
Likes: 10
From: Beavercreek Oh
72 Blower Motor INOP
The blower motor does not function on any fan setting.
I do not have power to the purple wire that supplies voltage to the blower motor. I do have 12v at the orange wire of the blower relay. I have tested the switch in the console and it is good as well. Any ideas? Would the relay or resistor be bad? Is there anyway to test either of these components?
I do not have power to the purple wire that supplies voltage to the blower motor. I do have 12v at the orange wire of the blower relay. I have tested the switch in the console and it is good as well. Any ideas? Would the relay or resistor be bad? Is there anyway to test either of these components?
Melting Slicks
Joined: Mar 2005
Posts: 2,095
Likes: 299
From: Midlothian VA
bad/no ground. run a temp ground to the motor and see if it works. motor is grounded by a black wire to the starter ground below.
also check that the left selector wheel is not in the off position.
also check that the left selector wheel is not in the off position.
Last edited by Hammerhead Fred; Nov 28, 2014 at 07:32 PM.
Thread Starter
Racer
Joined: Jun 2009
Posts: 316
Likes: 10
From: Beavercreek Oh
I would think the harness is good because all wiring has been replaced.
Melting Slicks
Joined: Mar 2005
Posts: 2,095
Likes: 299
From: Midlothian VA
I believe I do have a ground issue. After looking into it further the black ground wire on the blower relay does not seem to be functioning. When I check voltage from the orange to black wire I have 0 voltage. Orange to block I have 12v. Im wondering if I don't have a ground hooked up somewhere. I'm going to run a jumper wire tomorrow to test the system.
I would think the harness is good because all wiring has been replaced.
I would think the harness is good because all wiring has been replaced.
Thread Starter
Racer
Joined: Jun 2009
Posts: 316
Likes: 10
From: Beavercreek Oh
I believe I have that ground hooked up correctly. There is another ground wire that attaches to the blower motor relay. This ground is not operational when I test the orange wire to the black ground. I'm trying to track down where it obtains the ground through the harness or what it attaches to on the other end.
Thread Starter
Racer
Joined: Jun 2009
Posts: 316
Likes: 10
From: Beavercreek Oh
Thanks for the schematic!!
I just located the ground and now have a good ground at the blower motor and blower relay. I have no power to the purple wire at the blower motor on any fan setting.
How does power run through the blower circuit? Does it get power from the orange wire that is fused at the lt inner fender? If so where does it go from there? I'm trying to figure out if I have bad parts. IE: bad blower relay or resistor. I know the blower motor is good as I bench tested before it was installed.
I just located the ground and now have a good ground at the blower motor and blower relay. I have no power to the purple wire at the blower motor on any fan setting.
How does power run through the blower circuit? Does it get power from the orange wire that is fused at the lt inner fender? If so where does it go from there? I'm trying to figure out if I have bad parts. IE: bad blower relay or resistor. I know the blower motor is good as I bench tested before it was installed.
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Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
power up the relay and see if it clicks... If you power it up it should switch power. If it fails you need a relay... or a quicky repair.
If you open the relay up, you'll see a set of points inside.. If the magnet is good, the points may be burnt, you can file these and get the relay working.
Willcox
If you open the relay up, you'll see a set of points inside.. If the magnet is good, the points may be burnt, you can file these and get the relay working.
Willcox
Thread Starter
Racer
Joined: Jun 2009
Posts: 316
Likes: 10
From: Beavercreek Oh
power up the relay and see if it clicks... If you power it up it should switch power. If it fails you need a relay... or a quicky repair.
If you open the relay up, you'll see a set of points inside.. If the magnet is good, the points may be burnt, you can file these and get the relay working.
Willcox
If you open the relay up, you'll see a set of points inside.. If the magnet is good, the points may be burnt, you can file these and get the relay working.
Willcox
Thread Starter
Racer
Joined: Jun 2009
Posts: 316
Likes: 10
From: Beavercreek Oh
I think I may have another issue besides the relay. I swapped the relay to a known good one and still the blower is inop. What I question here, I can not get either relay to transfer power. I have constant power at the orange wire (key on or off) and a good ground as well. I opened up my original relay and it looks really good inside. So with 12 power to the orange wire (number 1 terminal on the relay) and ground (number 5 terminal on relay) should voltage transfer automatically to the number 2 or 3 terminals of the relay? Does the fan switch send power to the 2 or 3 terminals when the switch is on to get the relay to click / transfer power? I would think it would so the blower would not be running all the time. This set up has me baffled
Melting Slicks
Joined: Mar 2005
Posts: 2,095
Likes: 299
From: Midlothian VA
Have you verified that the blower motor actually works?
Run a known 12 volt line and known good ground directly to the blower and see if it works independent of the switch/relay/wiring/etc.
Run a known 12 volt line and known good ground directly to the blower and see if it works independent of the switch/relay/wiring/etc.
Thread Starter
Racer
Joined: Jun 2009
Posts: 316
Likes: 10
From: Beavercreek Oh
Yes the blower motor is good. I have confirmed. Im getting zero voltage at the purple wire to the blower motor. I removed the in line condenser at the blower to confirm that is not causing the issue either.
Melting Slicks
Joined: Mar 2005
Posts: 2,095
Likes: 299
From: Midlothian VA
So....just to verify - as I don't know how long you've owned a C3...
In my initial post I asked
"check that the left selector wheel is not in the off position."
Cause the fan will not run with the left selector wheel in the off position.
That wheel must be moved down to some other position before S1 in the diagram above becomes hot/closed.
In my initial post I asked
"check that the left selector wheel is not in the off position."
Cause the fan will not run with the left selector wheel in the off position.
That wheel must be moved down to some other position before S1 in the diagram above becomes hot/closed.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
So....just to verify - as I don't know how long you've owned a C3...
In my initial post I asked
"check that the left selector wheel is not in the off position."
Cause the fan will not run with the left selector wheel in the off position.
That wheel must be moved down to some other position before S1 in the diagram above becomes hot/closed.
In my initial post I asked
"check that the left selector wheel is not in the off position."
Cause the fan will not run with the left selector wheel in the off position.
That wheel must be moved down to some other position before S1 in the diagram above becomes hot/closed.
Thread Starter
Racer
Joined: Jun 2009
Posts: 316
Likes: 10
From: Beavercreek Oh
So....just to verify - as I don't know how long you've owned a C3...
In my initial post I asked
"check that the left selector wheel is not in the off position."
Cause the fan will not run with the left selector wheel in the off position.
That wheel must be moved down to some other position before S1 in the diagram above becomes hot/closed.
In my initial post I asked
"check that the left selector wheel is not in the off position."
Cause the fan will not run with the left selector wheel in the off position.
That wheel must be moved down to some other position before S1 in the diagram above becomes hot/closed.
I've owned my 72 for 16 years. Bought it as a project and am finally able to finish it up. I have a few odds and ends to straighten out but its getting there!
Melting Slicks
Joined: Mar 2005
Posts: 2,095
Likes: 299
From: Midlothian VA
Ok, went out in the cold to verify;
Relay orange always hot.
With switch on Hi, wheel on heat; upon key on, the relay clicks.
Both DBL & PPL go hot.
ANY attempt to remove the ground wire and the relay clicks off and fan dies. I see you verified the relay ground so need to work back toward the switch from the relay. Are you getting voltage at DBL at the relay (switch on, wheel on, key on).
Relay orange always hot.
With switch on Hi, wheel on heat; upon key on, the relay clicks.
Both DBL & PPL go hot.
ANY attempt to remove the ground wire and the relay clicks off and fan dies. I see you verified the relay ground so need to work back toward the switch from the relay. Are you getting voltage at DBL at the relay (switch on, wheel on, key on).
Melting Slicks
Joined: Mar 2005
Posts: 2,095
Likes: 299
From: Midlothian VA
I think I may have another issue besides the relay. I swapped the relay to a known good one and still the blower is inop. What I question here, I can not get either relay to transfer power. I have constant power at the orange wire (key on or off) and a good ground as well. I opened up my original relay and it looks really good inside. So with 12 power to the orange wire (number 1 terminal on the relay) and ground (number 5 terminal on relay) should voltage transfer automatically to the number 2 or 3 terminals of the relay? Does the fan switch send power to the 2 or 3 terminals when the switch is on to get the relay to click / transfer power? I would think it would so the blower would not be running all the time. This set up has me baffled
The relay is the HI FAN Relay. Sends 12+ direct from the horn relay to the fan motor to protect the switch circuit in the console when running fan on HI. For all lower speeds the switch in the console routes power through the resistor pack then on to the fan. If you have power on Orange & good ground on black at the relay and get no power at the fan/purple then either the relay is bad or your console switch is bad or has no power to it.
You can verify by probing for power at the DBL wire coming into the relay with the switch on HI. You can also verify by probing PPL for lower voltages with the switch on lo/med. No power means your issue is in the console OR your fuse is blown.
The switch depends on the fuse and/or S1 switch feeding it or the switch itself could be mucked up with gunk.
You could also inject +12 at the DBL prong of the relay which should cause the relay to pull in completing the circuit between Orange & Purple. If the fan fires then you know the relay, fan, & grounds are good and you can go dig into the console.
Last edited by Hammerhead Fred; Dec 6, 2014 at 10:15 AM.