No power to blower motor
 

This car was apart and am getting it together. I tested the blower motor and it runs good and quiet. I installed a new high blower relay (was missing). Turned key forward to run and no speeds on switch work to blower with dash switch slid over to heat (A/C car). Fuse is good. Could the switch be bad?

What make, model and year is the car?

Did you check both ends of the fuse with a test light? Looks good doesn't mean they are good. Accessory power, from ignition switch, goes through the fuse first then to the fan switch.

If your confident there's power going to the fan switch....Go under the hood and see if power is making it to the blower resistor.

just a starting place
Clay

This is a 72 Lemans.

..Go under the hood and see if power is making it to the blower resistor.
You mean to the high blower relay? That is where the blower motor wiring comes. Or, is the blower resistor tied into this too? I did replace the blower resistor with new also.
I'll check the fuse with a test light.

Blower resistor regulates current for fan speeds other than high.

High fan trips the blower relay and sends more power to the fan. That power comes from the back of the alternator.

Yes it's all tied together with a single wire going to the fan motor.

Clay

Thanks for that info.

My fuse tests good. No power to any one of the three terminals on the blower motor resistor with ignition in run mode. Does that send me back to the switch on dash to look for power?

Check that there is 12 volts at fuse terminal.
(that terminal to ground with VOM should be 12 volts)

If 12 volts there check that the wire to connector on switch has 12 volts.

If all have 12 volts then switch is bad.

:confused:

I have 12 volts at the fuse. But, using my test light at the brown wire going to switch was just a tad below 12 volts. I had a hard time unplugging the lead, so I poked the wire with my test light and checked the voltage off the test light. So, I assume my reading of 11.97 was because some of the power was going to light the test light. Does the switch need 12 volts to work or should it work at 11.97? Does this also mean the switch is then bad, not flowing current through it?

11.97 v is good.
If the wire coming out of the switch has no voltage, the switch is bad?


:(

Can you see the wiring connector coming out of the switch?
Should be three wires I think?

See if any of those have 12 volts with switch on.
Usually though if resistor is bad, it would still have high speed at blower.
(high uses 12 volts)


:confused:

I have the radio out and the glove box out so I can view from the front with a light and my hand through the glove box to grab wires. If I remember correctly, there were two wires going in (one brown) and there were some other wires next to it (I believe grey for one). I was going to ask what color would be the power out to check. At least before I go through the hassle of tearing the heater switch out of dash.

Brown is power for the blower.
Gray/grey is usually a light bulb power.


:)

Brown is power for the blower (coming out of the switch or going into the switch)? Because I tested a brown wire that led into the switch, but I assumed that was not power coming out. How do I know?

Correct, brown to switch, then 3 wires come out but think black is one of them for high. (black would be 12 volts, other colors less voltage)

:confused:

I found some issues that need to be addressed. I found I do have power to the blower motor resistor. But, only if I unplugged the high blower relay. Apparently I have the wrong relay, as it doesn't give me a any blower speed. I get nothing from that. My fan has four speeds and I get the first three without the relay. If I plug in the relay I get no power to blower motor resistor.

Update
 

I got the correct high blower motor relay and I now have high on blower motor, Woohoo! But, for some reason I don't have low. I actually have a fan on low, but it's the same speed as switched to the level two. So, my switch has 4 speeds, but one and two are the same speed. That's fine I guess, since the low I had before with the relay unplugged seemed like it wouldn't blow much air anyway. Just not sure why that happened.