1985 245 that has until just recently been my ideal winter car. Engine starts and warms quickly with the legendary Volvo heat coming on fast. When the temperature dropped to a record -36.5°C yesterday night, the frozen brick started up fine (albeit noisy), but I experienced a no heat issue. Engine temperature gauge gets up to normal, lots of air blowing through all vents, just freezing cold. Driving my daughter to a doctor's appointment with no heat was an experience I'd rather not repeat.

After 20 mins of driving and a couple of stops, hot coolant finally hits the heating core and blessed warm air entered the car.

Coolant level is good. The upper and lower rad hoses were warm, so does that rule out a sticking thermostat?

Thanks in advance for any advice.

Ray