Baffling Blower Motor Issue

[RaysnCayne]

Hey all,
My R10 just failed the annual safety inspection b/c the blower motor wasn't working (need functional defrost to pass inspection).
I installed a new blower motor not quite a year ago. And everything worked fine the last time I used the A/C, which was about 3-4 weeks ago.

1. I hooked 12v power from the battery directly to the blower motor and it whirred to life.
2. I put my test light in the big purple power wire coming from the relay, and it lit up when I flipped the HVAC lever over to "DEF" or any of the A/C options.
3. I pulled the resistor out of the firewall case and it looks fine. Tested for resistance/continuity and it seemed fine there too.

So now I'm at a loss as to what else it could be? Doesn't seem like it'd be a vacuum issue, but could it be?

 

[legopnuematic]

Copy and pasting what I wrote in your last thread about this:

If the blower motor stops/is intermittent, first thing I’d check is the heavy power wire going to the blower motor. The molded connector on the end can get misshapen/shrinks or something where it visually appears to be connected, but it’s actually not seated completely.

My 76 is that way, on occasion it’ll fall off or lose connection. Really need to replace the connector.

Easy enough to check, while running, set the blower on high and wiggle the wire. Should be easy enough to hear if it cuts in and out.

 

[RaysnCayne]

You're my hero, Spencer!
My purple wire end is in great shape. But I guess the retaining groove on the new blower motor tab is not quite in the OE location. The wire felt like it was plugged in fine as-is. But after some good hard pushing, it finally locked in and everything seems to work great now.
Thanks!

 

[idahovette]

Way to go @legopnuematic !!!! spoon fed