No Heat!

i have a 93 p/u 2wd and i have no heat. and with the cold winter here i need to fix it. the problem is that their is no control switch for the fan. my uncle had it brfore i did a few years ago and i think he ripped it all out. i had the dash apart when i put in my headunit and there was no sign of the swtich. i then tried to wire in a switch to turn on the fan and i found an open harness and used my test light and made a circuit and made it kick on. this is good but it takes like forever to get warm and i cant even feel it. is there any possible way to wire in a switch to make it work at a higher speed?
any help would be great,
thanks!