testing heater A/C blower resistor

You have it out? You can pretty much tell by looking at it. The problem with measuring resistance of ANYTHING that sees a lot of load, is that some loose / poor connection can "make" enough to satisfy the ohmeter and lead you down that lower road......the wrong one that is

Another example is high current diodes such as used in welders and alternators. You can NOT measure them with a meter, you MUST put them under substantial load

One way to do this is to get the connector/ wiriing down where you can access it, then "clip lead" the motor to one terminal, and "clip lead" power in from say,...........the fuse panel