I own a 1998 Chevy Blazer. Today was the coldest so far (I live in CT) since I've had the car (3 months) and when I first started the car it was fine. After driving about 10 minutes it started blowing cold air even though I hadn't changed the settings. Any idea what's wrong and how to fix it?

 

Thermostat failed, air in coolant system, heater core plugged up, coolant level wrong - one or all. Any strange noises from the dash area and what does your temp gauge read?

 

Now heat is working intermittently.... when it feels like it..... won't be fun this winter in CT.
No strange noises, but I've recently had issues with the temp gauge rising (see my other posts).

 

change your thermostat. it takes like 5 minutes, and you'll have heat buy the time you clean up yourself and your tools.

also take note of the colour of your coolant, it's the Dex Cool, not the old "green stuff", ethylene glycol. alot of people are saying to get rid of the "Death Cool", and flush 'n fill with traditional green antifreeze. i personally haven't had any problems with it (yet), but others swear it's crap.

glad to see you're back on here. but remember, you don't need to come around only when your truck is having issues.