I've been checking the coolant temp trying to find out why my heater isn't producing even warm air. After driving 25 minutes(10 min at 45-50mph, 15 mins up a canyon road), the coolant temperature (at the radiator filler mouth) is around 120-130 degrees F. The thermostat is a new 180 deg one, the temperature gauge in the dash reads at about 2/5th and rarely gets up to 1/2 gauge.

I'd like some opinions about this, it doesn't seem right that the engine would be running this cool. That may or may not be the heater problem, but it's a good place to start. A year ago when the temp gauge ran at 1/2 gauge normally, the heater would put out a little warm air , but not very impressive.

John
1984 22R long bed, 5 speed.