AC and Heater does not blow cold/hot

Hello. I own a 1990 Toyota Celica GT-S with a 2.2 L 5S-FE engine and it is well over 100k miles. My climate control system is not blowing cold or hot air. The fans are working. The refrigerant level looks good as there are no bubbles or foam in the sight glass. Coolant is full. Thermostat seems ok. I'm guessing it's a electrical thing since both heater and AC are not blowing their correct temperatures. I suspect one of the control relays but I don't know which one. I'm also probably wrong since I am not a mechanic but I'm doing the best I can with the repair manual I got. Does anyone have any ideas?