If you are getting no action, THen you need to chase power.
You have two choices, Start at the blower motor or at the battery and measure at each connection/relay, fuse or switch, till the meter changes from either no voltage to voltage or the other way around.
Normally for this kind of trouble shooting I use a test lamp..
I took a blade type license plate lamp socket (HELP counter at any auto parts store, HELP is a brand name) and extended one lead, put in a dash lamp size bulb (it fit) put clips on the ends of the leads.. Hook one to a known good ground then touch the other to the test point.. LIGHT=Power, no light = no power
When the light either comes on, or fails to,, the problem is between the last two points.. If the light comes on on the blower motor itself, then the problem is either
1: Motor ground connection or 2:Motor itself.
If the light fails to come on when touched to the battery the problem is either 1: Battery ground (MOve ground clip to negative terminal of battery to test) or 2: Battery is dead.
NOTE: There is often a 2nd fuse on devices like this.. Not only is the power feed to the furnace fused.. but there may be a fuse at or near the furnace. (Belt and suspenders anyone) usually one is larger so it should never blow.. but fuses wear out believe it or not.
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