Truck Repair: ac on high, orange wire, purple wire

Question
its me again with the heater and ac that works but not on high was told chk the blower relay with the ign. off chk the red wire for 12 volts at all times   it does then with key on and blower set on high chk the orange wire for 12 volts all time it does  vehicle 85 chevy fullsize blazer 4x4 help

Answer
Hi Art,
OK..That gets battery power to the relay, and the orange gets switch power to the relay. Check the wire to the blower motor, Purple, and see if it is getting full battery voltage when the orange wire is.
If the Purple wire shows less voltage than the red wire, then the relay isn't working, and I would expect it to run at low speed when Hi is selected.

I would wiggle the connections on the relay, and maybe even tap on it.
Another thing to check is make sure the black wire from the relay is grounded good.
Van