First, check the battery and starter cables for their tightness or free of corrosion and physical damaged.

See this Starting system simplified diagram. Have a help from an assistant to crank the engine, use a 12 volt light tester or a digital voltmeter, apply it to the starter control circuit.
If there is light or 12 volts and the starter isn't cranking, then the starter is the culprit. Have the starter to bench test for free at the local auto parts stores.
If there isn't no light or no volts, then the ignition switch is the culprit.

http://www.samarins.com/glossary/starter.html


Note: a 3/4 charge battery is 12.50 volts
A discharge battery is 11.75 volts.
A battery under a cranking load and it is reading less than 7 volts,it will be a recycled ( junk ) battery.

A. Insufficient coolant , trapped air in the cooling system might not have enough coolant to full fill the heater core.

The hot coolant flows from the engine to the heater core through the "inlet" hose. After circulating through the core, the coolant returns to the water pump through the "outlet" or "return" hose. Both the inlet and outlet return hoses should feel hot when the engine is at normal operating temperature and the heater is on.

1. If the both heater core hoses were cooled, then this vehicle might have an insufficient coolant in the cooling system.
2. If the heater core inlet hose is hot and the outlet hose is cool, the heater core might be clogged.

Note: check the radiator coolant level and top it off as needed.

Some cooling systems have air bleed valves built into the system to aid in the removal of air pockets. Advice: For many cooling systems, the method of removing air pockets is to start the engine and allow it to run with the radiator cap off or loose until all the air escapes from the neck of the radiator. For some systems this method is not sufficient, and the manufacturer has installed air bleed valves usually near or on the thermostat housing.


B.The blend door actuator is a servo responsible for controlling the mix of warm air from the heater core and cool air from the A/C and outside. If it malfunctions, your climate control system may not respond properly when you change the temperature on the climate control system.

See this repair guide for the blend door actuator.

http://www.autozone.com/.../...rGuideContent.jsp

If you already change relay the front blower control switch it's bad.The blower motor get power front the relay and the control switch ground it..