92 Astro Van - No Heat

I have a '92 Astro and just this morning (the first day of any significant cold and snow, of course) the blower runs fine, but no heat - only cool air.

I ran the van for about 15 min in the drive to warm it up and scrape, then an 8 mile stop-and-go trip to work - usually the defrost is blowing hot air before I get down the street when I do this. No hot air at all this morning.

Also, the water temp indicator looked normal - no overheating or anything. I ran the defrost earlier this week and it worked fine. So, it seems whatever happened - just happened.

Any suggestions where I should start looking this weekend? Heater core?

Any input would greatly be appreciated.

Thanks!

Low coolant level is the number one reason for no heat- make sure your radiator is full and the burp box has enough in it-- if you are truly low- then you need to find the leak- can be water pump or some other hose-- if no leak found- then pressure test radiator- you may be burning coolant internally......a much worse scenario...

Update...

This weekend I checked the fluid - a little low. I flushed the radiator and replaced the thermostat & filler er up. I now have heat, but it seems almost intermittent - it will be hot, then cool down, then get hot again - all while driving. Also, I started to notice a foul smell when the blower & heat is on. Kind of like eggs ???

I could not detect an obvious external leak as of yet.

Could be a blocked or leaking heater coil. the heater coil is inside the black plastic cover just above the front passengers feet. if you flushed the radiator I hope you hade the heater set to hot so that you flused the heater coil too.