hi!
My blower motor on my 69 chevelle isnt running. I have power through the fuse by the relay and I have changed the relay. I have no power coming through my purple wire that connects to the blower motor. Does anyone have any idea whats going on here? Any help would be greatly appreciated. I have done a search to no avail and the heating and cooling section doesnt seem to get to many hits. Thanks in advance for any help!!

Is there "NO" voltage on the fan end of the purple wire, or is there "LOW" voltage?
If there is "ANY" readable voltage there, then there might be an issue like I found with my wiper circuit. The inside if the wire (the copper) is corroded up and has increased the resistance. This increase in resistance has created nothign more than a voltage drop from the source of voltage to the end of the wire.
Trace it back and do the following:
Measure for voltage at the "upstream" end. More voltage (but still low) would confirm the corrosion theory.
Another possibility if these measurements occur this way but the wire is not corroded is a possible short through a poor ground. This can drain off voltage, thus not leaving enough to operate the fan.
If you have 12VDC at the "upstream" end and 0 VDC at the fan end, check for continuity. The wire likely has an open. Also check the connector to the fan for corrosion. You could "jumper" 12VDC to this connector directly to "bypass" the original circuit and prove the fan even works. This would be one of the first steps I'd take.
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thanks dan for the input! However, I have zero voltage at the fan end of the purple wire . the harness is new as is the blower. i checked the grounds and everything is grounded. Any other ideas???

Check the fuse in the fuse box for heat/ac. IF this fuse is blown you will not have any power to the fan at any speed. The fuse and realy on the firewall is for High Speed only. In order for high speed to work you need power to the fan switch which comes from the fuse in the fuse box.

The relay is for Hi-blow only. Try this:
1, Check for power on the orange lead on the relay connector. This is 12 volt input for high only. Should always have 12 volts.
2, Select HIGH on the switch and set the temp control lever to HOT.
3, Measure the purple wire on the relay connector. Should have 12 volts. If not:
4, Measure the dark blue on the relay connector. Should have 12 volts. This is the wire that closes the relay. If no 12 volts the problem is under the dash.
5, Check for 12 volts on the brown wire plugged into the fuseblock. This is the power wire that goes to the switches to operate the relay. If you have 12 volts here, problem is with either the speed selector switch or the temp control lever switch.

thanks guys! Ill check those suggestions out and let you know what i find. Dont ya just love electrical problems???????????

its working now!! Thanks everyone, especially John for the step-by-step. I wasnt getting any power to the switch. Once i fed it some juice, it ran like a top. Once again, thank you all for the assistence!!!

Originally posted by mkarstm:
thanks guys! Ill check those suggestions out and let you know what i find. Dont ya just love electrical problems??????????? Cool, actually Steve also nailed it. Without electrical problems I wouldn't have the coin to feed the wife's dog.