Have a new blower motor-2 yrs old- and replaced the fan switch with a used one. Has been working great until today-no blower. AC/comp kicks on, all vac hooked up-the fan lost low speed and then went out after a few months. Could it be the relay or resistor? Does anyone know where they are located on a 71 350 Skylark-factory air-new compressor etc. Looked at the shop manual and that didn't help. Also-when you turn the fan switch to high you can hear a click from under the hood-it's not the a/c compressor-it's off. Thanks-Chris
Replaced all the ground straps and added a couple a while ago douple checked and nice and tight-since it slowly lost speeds I'm hoping its the relay-40+years old-served it's time. TX
Very easy to diagnose. Put the fan switch to high. That will bypass the blower resistor and apply 12v to the fan motor. Now check to see if you have 12v at the wire going to the fan. If you do and the ground is good, the fan motor is N/G. Commonly, the relay is whats bad, but "test, dont guess"
I can do that....but how the heck do I get to the blower motor to clamp the wire on w/o takin the car apart!
There should be a black wire with an orange tracer going to the fan. Follow it to the bulkhead connector and check voltage there Here is the wiring diagram with A/C
So where it plugs into the relay see if I have 12 v at the connector? If not that would be the switch-right. If you connect 12 v on the line going out of the relay the fan should blow? The only fan wires at the relay are brown.
I have to apologize, I posted the diagram from the 1970 manual which doesnt include an A/C relay. The 71-72 wiring is different. My mistake. Didnt mean to confuse you more. Here is the right schematic. The black/ orange wire to the blower motor goes back to the A/C relay on the firewall. You can check power there. You also have a #10 red coming in from the BATT. Its a fairly somple curcuit.
:grin: Yep-12v at the brown wire going to the blower-any other points between there and motor where there could be a prob-2 yr old blower motor-wiring harness is in great shape. This seems to coincide with my son having a "tire fry" and leaving 5 lbs of rubber on the asphalt before he went and bought new rear tires!
So tested the current coming into the relay(the rectangular deal on the firewall next to the volt reg) and tested the current coming out AND the current at the array beneath the POA valve on pass side-all 12v....so does it look like I'm changing a blower? The only grounds I have are the braided copper to the engine/firewall, firewall to frame, battery to fendor and the other big ones-is there a specific ground wire I am missing that only grounds the blower motor-I am an electrical 'tard so this stuff is a litttle confusing. Thanks!
Just think of the wiring conductors as tiny water lines. Relays/fuses/switches are water valves, some controlled differently than others. Voltage = water pressure. Amps = rate of flow gals./ minute.
The blower motor worked-briefly today-after taking the relay off and opening it up to see if any wires were fried...so me thinks it's the relay or another electrical component that has given up after 40 years. The blower motor is only 2 years old so I'll do some testing-just didn't want to install another blower-fingers crossed that it's something simple!
Problem solved-kind of. The ground strap to the firewall attached to the blower was loose at the blower-got a zip tie and pulled the ground strap up and it firmed up the connection/screw on blower-works perfectly....but I know this will fail eventually. Does anyone know how to get to that screw on the blower motor w/out taking the inner fender off??
If it is a non AC car you may be able to carefully unbolt it and rotate it clock wise enough to do the job.
It's an A/C car..I really don't want to remove the inner fender to tighten up a screw...but maybe since it's working with my temporary patch I'll just wait to see if it gives....probably on the coldest day of the year when you want heat!
