Those are three very good points. If you have a temp gauge that goes up and down as well (not nessessarily in accordance with the heater temp though) then I would say it is the coolant level, which should not be checked when hot as you will not get a proper reading and may get injured too. Before starting the vehicle when cold, take off the radiator cap and check.
It is possible that you may have a clogged heater core and does not allow circulation until a given amount of pressure develops in it. I have seen it a lot now that it has been cold. See it every year actually. If you are handy enough, unclamp the heater core hoses and blast it through with a jet nozzle in both directions. If it is clogged, you will see the dirty muck come out of either one side or the other.
If it turns out that your S-10 heater core was gukked up, I would strongly consider having your coolant system flushed because there would then be a likelyhood of plenty of the same resting in the lower portions of the blocks water jackets.
Thermostats do stick, but not as often as cooling systems get filthy enough to cause blockages. For sure you should check the tensioner on your serp belt too.
Good luck with that man. Hope you get it because it sucks not having heat on those winter mornings when you can really use it.
Remember coolant is mixed 50/50 with water, or buy premixed stuff.
It is possible that you may have a clogged heater core and does not allow circulation until a given amount of pressure develops in it. I have seen it a lot now that it has been cold. See it every year actually. If you are handy enough, unclamp the heater core hoses and blast it through with a jet nozzle in both directions. If it is clogged, you will see the dirty muck come out of either one side or the other.
If it turns out that your S-10 heater core was gukked up, I would strongly consider having your coolant system flushed because there would then be a likelyhood of plenty of the same resting in the lower portions of the blocks water jackets.
Thermostats do stick, but not as often as cooling systems get filthy enough to cause blockages. For sure you should check the tensioner on your serp belt too.
Good luck with that man. Hope you get it because it sucks not having heat on those winter mornings when you can really use it.
Remember coolant is mixed 50/50 with water, or buy premixed stuff.