Check for any coolant leaks. If found they need to be fixed or engine may be overheated and cracked.
No cabin heat is usually caused by low coolant level or having gas pockets in cooling system which prevent hot coolant to go into the heater core.
Read the coolant burping procedure in this site. Very easy and straight forward:
1. On top of the white coolant reservoir, remove the black cap and the white butter fly plug. Add coolant to reservoir to HOT level.
2. Run engine alternately between idle to 3000 RPM to heat up engine until the fan starts running.
3. Monitor the engine temp gauge. Shut engine down if overheat and restart in 1 minute. Engine may suck coolant into block from the reservoir. Add coolant into the reservoir, keep it at HOT LEVEL.
4. As engine heats up and start opening the thermostat to take coolant from radiator into engine block it will pump coolant out to radiator, any gas bubbles in the cooling system will be driven out to the radiator and squirting out with hot coolant spray out the butterly hole.
5 You can also reinstall the butterfly plug and just crack it open enough for gas to squirt out without spraying coolant.
5. When there is no more gas squirting out, and the small chamber below the butter fly plug is full of coolant, system has no more gas, is full of coolant. You are done. Reinstall the reservoir cap.
