A.C. Blower question

[landarts]

First let me give you a little background. The truck is a 72 lwb Cheyenne with factory air, that I am in the process of restoring. When I purchased the truck several years ago the hot and cold lever on the A.C. controls was broken and the fan switch would only do low and medium-- no high setting. I removed the switch and sanded the contacts and applied die-electric grease to contact points. Still no High setting. One more thing the heater core was toast . So I replaced the heater core, rebuilt the A.C. control unit with new levers, and replaced the fan switch.

When I turn the key to ACC and put the switch in high mode it blows like crazy. When the truck is running I dont get half of air in high mode versus when the motor is not running. My questions is does the A.C. relay have anything to do with that or am I just fishin....?

thanks
Jim