Re: Bleeder valve location?
Cooling systems for normal road going cars are designed to self-bleed by returning air to the coolant tank and sucking more coolant in as needed. You might notice for instance the coolant levels vary between a hot and a cold engine. There wouldn't be a valve to bleed; the system is "open" loop, unlike the pressurized A/C system with HIGH and LOW ports and valves.
You heat might not be working for other reasons. On cars that use a secondary radiator or pipe (usually located around the firewall / dashboard-windshield area) to circulate hot coolant, a fan draws (or pushes) air over it and into the cabin. There will be some sort of vane or little door that will be actuated and opened when the occupants request heat. This vane will be shut off when there is a request for A/C or ambient air.
As such I speculate that you either have an electrical problem with one of those actuators or a mechanical problem (stuck closed). Usually those are pretty deep inside the dashboard - in the area of the cabin air filter (but not necessarily).