Heater was optional in the Standard model for most countries. All USA models came with a heater (by law).
Heater Inspection
Heater core:
- Leaks (before removing, check for leaks in passenger area, under carpet, on firewall cardboard, etc)
- Flow (ensure it is not plugged). You can test similar to radiator blocked test
- Clean out debris in exterior of core
Hoses: Check for cracks, overly soft hoses, tight clamps
Flow valve: ensure it opens & closes easily through entire range. Also check linkage for easy and complete movement (before taking apart)
Air ducts: Ensure they are clean and connected properly
Electrical: Ensure fan spins at both High & Low speed
Coolant Thermostat: Test