Pontiac Repair: blower motor does not work on high setting, pontiac transport, purple wire

Question
i have a 93 pontiac transport and the high setting for the blower motor has stopped working, the low and medium setting work fine.
every now and then the high setting will work for a short while.
i have jiggled the wire but no luck.

Answer
Hi Pete:
My guess is possably a hi blower relay is bad or a wiring issue at the hi spped blower relay. In very rare cases I have seen the wiring at the blower speed switch burn up. More then likley the issue is the relay. The relay is mounted to the heater box under the hood. It will have a heavy gauge purple wire going into the relay that purple wire is the output feed to the blower motor. I don't know what the other color wires are on the relay my online service manuals for GM only go back to 1998. Good luck :)