C2 heater/AC blower motor still won't work

[Larry S.]

I posted a thread a few weeks ago, and I greatly appreciate all your help. But, my blower motor still doesn't work. Here's what I've done:

1. Before replacing the motor, I checked power to the positive connector on the blower motor; it had power.

2. I connected a jumper cable from the positive connector on the blower motor to the hot terminal of the battery; motor did not run, so I replaced the motor. Once installed, I checked the new motor with a jumper cable, and it worked.

3. Turned on the ignition key and the fan switch. Motor worked on high speed only. Turned the switch off, then on again; motor worked on low and medium but not high. Repeated this two or three times. Then turned the switch off, then on again; no speeds worked.

4. Replaced the heater blower resistor; no change--no speeds worked. Jumped the motor again from the battery to make sure I wasn't imagining things when I previously heard it running; it runs.

5. Replaced the blower motor relay; no change.

I haven't been able to locate the fuse from the horn relay, but that should only affect high speed operation, shouldn't it? If the motor is testing for power at the wire to the motor connector, shouldn't it run on some speed, either low or medium?

The fuse in the fuse panel is good. The only other clue is that when I move the switch through the speeds, I hear a faint popping noise from the radio speaker with each click of the switch. If it's the switch, how hard is it to replace?

Please help before I put a bullet through the motor. Thank you.

[Joe R.]

Re: C2 heater/AC blower motor still won't work

Hi Larry:

I'm sorry to hear you are having so much trouble with this. I have not had a chance to study the wiring diagram to see whether the in-line fuse on the driver's side fender affects the two lower speeds.

However, I suggest that you locate this fuse and check it. In response to your earlier question I posted a photo that shows the "big red wire" and the white in-line fuse holder. The TDB software will not let me attach the photo again, but hopefully you can find it.

Regarding your voltage measurements, there is a subtle aspect of electricity that may be affecting your results. If you measure the voltage at the connector with the motor disconnected, you will not see the possible effects of a high resistance connection. If the switch and the associated wiring have even 20 ohms of series resistance, the motor will not run at all, or will run very slowly.

If possible, measure the voltage at the motor with the motor connected and the switch turned on (this may require a bit of fixturing with some wire).

I suspect that your motor is fine but for some reason the connections have too much resistance. For the two lower speeds this might be related to the switch in the dash. For the high speed mode, either the inline fuse or the dash switch that controls the relay may be the problem.

[Albert P.]

Re: C2 heater/AC blower motor still won't work

The best thing to do is to check the switch in the dash; if you look at the wiring diagra, it indcates wht contacts close for each position selected; I would disconnect the connector at the switch and use an ohmeter to check the contact sequences as shown on the diagram; you will need to take the radio out to get to the switch; it may something as simple as spraying the switch with contact cleaner and rotating many times to clean it up.

[Larry S.]

Re: C2 heater/AC blower motor still won't work

Joe, the in-line fuse in the "big red wire" is good. So, probably the switch?

Albert, is the only way to get to the switch is by removal of the radio? Would removing the left side radio panel get me access?

Thank you.

[Joe R.]

Re: C2 heater/AC blower motor still won't work

Joe, the in-line fuse in the "big red wire" is good. So, probably the switch?

Albert, is the only way to get to the switch is by removal of the radio? Would removing the left side radio panel get me access?

Thank you.

Hi Larry:

The switch in the dash is certainly a suspect, but since it is PIA to get at the dash switch, I'd suggest that you do a few more checks to rule out other possibilities.

There are other subtle problems related to grounding that may be causing problems. In addition, there is a series-connected filter capacitor in the power lead to the motor. If this assembly has developed a problem, it could be introducing some extra resistance that is limiting current to the motor.

I checked the wiring diagram to see how all this is put together. For the low and medium speeds, power to the blower comes through the dash switch to the resistor assembly and then on to the motor (through the filter capacitor assembly). For high speed, the dash switch simply sends power to the coil of a relay that directly connects the "big red wire" to the motor (again, through the filter capacitor assembly).

Furthermore, and this may be helpful, if you turn on the AC, there is a separate mechanical switch that sends power to the AC clutch AND the blower motor low speed setting, *bypassing* the dash switch for the fan speed control.

To confirm that the dash switch is the culprit, I would suggest trying the following three tests:

1) Turn the dash switch to low and confirm that the blower does not run at all. Then momentarily turn on the AC (engine does not have to be running) and confirm that the AC clutch engages. If the blower motor is now operating on low, that suggests that the low setting on the dash switch is bad.

2) Have someone turn the dash switch to high while you hold your hand on the AC relay. If the dash switch operates correctly in the high position, you should feel the AC relay engagage with a distinct "click." If the AC relay does not make any sound at all, that suggests the high position in the dash switch is bad.

3) This third test will eliminate both the dash switch and the AC relay. Remove the three-terminal connector (with red, purple, and blue wires) from the AC relay. If you connect the red wire to the purple wire, the blower should run on high. If it does, that suggests that the dash switch and/or the AC relay are defective.


I suggest that you try these three simple tests before you dig into the dash. If all the tests point to the dash switch as the culprit, that might be the next thing to check.

Keep in mind that a simple corroded connection anywhere in the system could cause the motor to not run. You may want to turn the dash switch on and then wiggle each of the connectors one at a time to see if that affects the blower.

[Larry S.]

Re: C2 heater/AC blower motor still won't work

Joe, thank you for the excellent suggestions (and for taking the time to make them!). The only test I have done is to turn the ignition switch on, put the fan switch on low, and pull the A/C knob to 'on'. No fan.

I'm ready to check the A/C relay, but where is it? (I told you I don't know anything about electricity!) Thank you again.

[Joe R.]

Re: C2 heater/AC blower motor still won't work

Joe, thank you for the excellent suggestions (and for taking the time to make them!). The only test I have done is to turn the ignition switch on, put the fan switch on low, and pull the A/C knob to 'on'. No fan.

I'm ready to check the A/C relay, but where is it? (I told you I don't know anything about electricity!) Thank you again.

Hi Larry:

When you tried that test, did the clutch on the AC compressor engage? The clutch and the low-speed fan override are controlled by the same mechanical switch that engages when you pull out the AC control knob. Sometimes you have to pull the knob out firmly to get the switch to engage.

The attached photo shows three things that may be of interest:

1) On the right is the resistor assembly.

2) On the left is the AC relay. Note the ground wire connected to the AC relay. I believe this is required in order for the relay to operate.

3) Draped over the AC relay is the unused motor power lead from the non-AC harness. When AC is installed, it gets its own motor power lead and the other one is simply taped off.


I will be very interested to hear the results of the other tests.

[Wayne M.]

Re: C2 heater/AC blower motor still won't work

Larry -- Joe R. offers some excellent advice. I'll add a few suggestions. That bypass filter / capacitor to the blower motor is only to supress static on the radio --- it is not necessary for the tests you are doing. I'd bypass it completly by unplugging the orange wire from the engine harness that connects to this mini-harness, and plug directly onto the +ve terminal on the blower motor. If it works, then it's this condenser that's at fault.

Also, it is not necessary to turn the ignition to "ON" for these blower tests; just turn to "ACC" and you should get the same, but with lower resistance (especially if the distributor points happen to be closed).

On Joe R's point #1, I'd turn the blower motor OFF at the console switch; then when you turn the A/C on, the low speed blower should start, even with the blower switch at OFF.

I have forgotten your original post, but if you have a '64 or 65 coupe without N03, it's a little more complex due to the interconnect between the rear compartment exhaust fan and the blower motor.

We're all awaiting for the results, because your symtoms are so weird.

[Jack H.]

Re: C2 heater/AC blower motor still won't work

Why knee jerk on this? A voltmeter probing across the blower motor to ground (pierce the blower motor's power lead-in wire with a pin to get a decent probe), ought to record nice and stable voltage steps from battery B+ down in lock-step to the position of the cockpit fan switch going from Max to Off.

If voltage readings are erratic or some steps are missing, you've got an 'upstream' fault or fault(s) to find and fix....

[Larry S.]

Re: C2 heater/AC blower motor still won't work

Here's what happened: since I live alone, there was no one here to turn the A/C on while I felt the relay for a 'click'. I moved on to the third test--connecting the red and purple wires at the relay. The first two attempts, nothing happened. On the third try, there was a spark at my connections, and the motor ran on high.

I plugged the connector back into the relay and tried the fan switch--all three fan speeds worked! I repeated turning the switch through the three speeds and it worked for several repetitions. I had the ignition switch 'on' during all of this; does this make a difference? What was going on? BTW, that relay is new; I replaced it last night.

Finally, the low speed comes on now when I turn the A/C on. I just went out to the garage and cycled everything again, and it still works. What did I jar into working? And, does everything seem to you to be working as it should? Thank you, everyone, for all the help you've given me.

[Joe R.]

Re: C2 heater/AC blower motor still won't work

Here's what happened: since I live alone, there was no one here to turn the A/C on while I felt the relay for a 'click'. I moved on to the third test--connecting the red and purple wires at the relay. The first two attempts, nothing happened. On the third try, there was a spark at my connections, and the motor ran on high.

I plugged the connector back into the relay and tried the fan switch--all three fan speeds worked! I repeated turning the switch through the three speeds and it worked for several repetitions. I had the ignition switch 'on' during all of this; does this make a difference? What was going on? BTW, that relay is new; I replaced it last night.

Finally, the low speed comes on now when I turn the A/C on. I just went out to the garage and cycled everything again, and it still works. What did I jar into working? And, does everything seem to you to be working as it should? Thank you, everyone, for all the help you've given me.

Hi Larry:

This sounds very encouraging. I can think of only two things that could have caused the behavior you describe:

1) A bad connection (probably due to corrosion) on the connector contact for the purple wire. Of the three wires on that connector, this is the only connection that is common to all speeds and to the mechanical AC bypass switch that puts the fan on low speed when the AC is on.

2) An intermittant problem downstream of the connection for the purple wire. This could be caused by a problem with the series-connected radio suppression capacitor assembly or with the connection to the motor itself.

Fortunately, all of these things are fairly accessible. If the blower stops working again, leave the switch on and try wiggling the connector on the relay and at the motor.

If that doesn't have any effect, you may have a problem with either the capacitor assembly or with the additional connection that it creates in the motor's power lead. You can remove the capacitor quite easily. It is part of the last foot or so of the power wire that goes to the motor. It is just there to keep static out of the radio, so there is no harm in removing it temporarily.

[John H.]

Re: C2 heater/AC blower motor still won't work

I had the ignition switch 'on' during all of this; does this make a difference?

Larry -

With the key in the "on" position, current flows from the ignition switch through the ballast resistor to the coil, and if the points happen to be closed (completing the circuit to ground), it can overheat the coil and/or burn the points. That's why there's an "Accessory" position - that energizes everything in the car EXCEPT the power feed to the coil, so there's no issue with the resistor, coil, or points.

[Robert C.]

Re: C2 heater/AC blower motor still won't work

Joe,

I'm trying to figure out some wiring on a '67 SB with AC. I saw this post and maybe you can answer this question.

Currently, in the '67's "past life", someone connected the heavy purple wire that comes of the harness right above the blower motor to the motor. This wire had a molded soft rubber plug on it. A 2 wire black ground wire out of this harness also connects to the motor housing.

Undoing some of the wiring, I found a heavy gauge orange wire with a 2 wire black wires that branch off the harness, between the passenger valve cover and the evap housing. It has the same soft rubber molded end on the orange wire and the black wires (2 different gauges) tie together with a plastic connector.

Looking at the manuals, it appears that these wires (orange and black) go to the motor.

When you noted in this post the purple/black are simply "taped off", that's been the first I heard of this. I keep thinking these wires had to go 'somewhere', but no options seem to exist......is that correct? The purple and black wires just get wrapped with tape and tucked away?

Bob

[Joe R.]

Re: C2 heater/AC blower motor still won't work

Joe,

I'm trying to figure out some wiring on a '67 SB with AC. I saw this post and maybe you can answer this question.

Currently, in the '67's "past life", someone connected the heavy purple wire that comes of the harness right above the blower motor to the motor. This wire had a molded soft rubber plug on it. A 2 wire black ground wire out of this harness also connects to the motor housing.

Undoing some of the wiring, I found a heavy gauge orange wire with a 2 wire black wires that branch off the harness, between the passenger valve cover and the evap housing. It has the same soft rubber molded end on the orange wire and the black wires (2 different gauges) tie together with a plastic connector.

Looking at the manuals, it appears that these wires (orange and black) go to the motor.

When you noted in this post the purple/black are simply "taped off", that's been the first I heard of this. I keep thinking these wires had to go 'somewhere', but no options seem to exist......is that correct? The purple and black wires just get wrapped with tape and tucked away?

Bob

Hi Bob:

Here's a quick response that answers part of your question. I can look into the specific wire colors later if necessary.

The wire harness for a base 67 without AC has a connection for the blower motor and perhaps a couple other wires (I would need to do some research to clarify how many wires and what colors are involved wires).

When AC was installed, an additional AC wiring harness was added. This additional harness replaced the motor connection of the base configuration. Since the base configuration motor connection wire was part of the whole base assembly harness, it was simply taped off and pushed aside.

I think part of what you are seeing is the unused motor connection.

[Robert C.]

Re: C2 heater/AC blower motor still won't work

Thanks Joe,

After digging into some posts, I was pointed to the AIM and sure enough, on E1 they show the purple/black wires stay connected and the orange/black get taped off......

Thanks for your help in verifying this !

Bob