I know it is late July and its kind of stupid to be asking this question, but it is something i want to take care of.

The heat in my 98 Blazer LT doesn't work, It just blows cool air. My A/C work great and is very cold. What can be causing the heat not to work even in the summer? I would think that it would at least blow air as warm as the outside temp but it stays cool.


Thanks in advance
Brian

 

If all of your modes for the climate control work, then it is quite possible that your heater core is plugged. 1st thing though, make sure that your radiator is full.

If the radiator is full, then I would have to recommend that you pull the lines off that go into the firewall and flush through them with a garden hose. Alternate flushing through one hose and then into the other until you get clear water out of both sides.

 

As Kyle stated, flushing the heater core, if blocked, will restore your heat. A quick simple test to determine core plugging is to grab each hose going to the heater core (with engine temperature up to run temperature). If one hose is really hot (supply from engine) and the other is not (return to engine block), your heater core is plugged. If they are both really hot, the core is not plugged and that points you to the temperature control system, etc.

 

That works to a certain extent... But if the flow is restricted in the core, but not blocked, then you will have equally hot hoses. But since portions of the core are blocked, you won't get the output required to heat the incoming air.

 

Very true, however, I gotta believe that even a partially restricted heater core will still be able to output some "warm" air. Brian's original statement says it only blows cool air, which reinforces the probability that the heater core is plugged rather than partially restricted. Mine was totally plugged when I got my Blazer. I backflushed the system and blew out a 1/2" thick plug of red mud into a catch container. I've had high heat output ever since. Before the back flush I had NO heat whatsoever and my hoses were 1 - HOT, the other NOT hot at all.