My 2001 Chevy Blazer was blowing cold air when I had the heat on. My husband flushed the line to the heater core and a bunch of junk came out and now my heat works great. My 2001 Chevy Blazer was blowing cold air when I had the heat on. My husband flushed the line to the heater core and a bunch of junk came out and now my heat works great.
Check the engine thermostat. Its probably stuck open.
A bad engine temp sensor can do that.
Check the 96 Blazer for any vacuum leaks in the system. A vacuum leak can cause the air flow to only come out of the heat vent.
It is located under the AC and Heat instrument panel
Is it blowing cold air only or not blowing any air at all.
Drain the blazer radiator. Refill with water. Open the heat on high, start the engine for a few minutes. Drain the system again Repeat this several times to get all of the old coolant out.
I believe that it is very touchy and you have to do it very gently so that the off lines up with the one on the knob exactly and if your's is as smooth as mine it is very hard to find that line with out going over or under.
If your windows fog up you thermostat may not register because you heater coil may be broken.
possible bad heater control valve?
Need to know if the blower is working or not and if the air coming out is hot, warm or cold.
Heater Airbound? Heater control cable not working? Heater core plugged?