89 regal heat problems

i have an 89 regal gs, the 3.1l v6. theres little heat. it seems that the fan is blowing fine. we spent 3 hours trying to fix it. replaced the thermostat, flushed everything out, replaced the control unit. i still believe the problem is electrical. when you try to adjust the temperature control, you can't feel the luke air get warmer or colder. and with electrical, it could be a power window motor screwin up my heat. haha. it seems like everything else is working fine, im just lost now on what to do. any suggestions?