1998 Blazer - no heat

[tokes]

I have a 1998 Blazer LT with a 4.3 liter engine, I have changed the thermostat and I had the coolant changed and a complete system flush done. I have checked the lines in and out of the heater core and they seem to be at the correct tempature. My engine temp is gauge reads a consistant 92 deg celcius. The fan blows like it should on all settings and everything seems to be functioning properly except for the lack of hot air. The A/C also works fine.

[swalt]

Are both heater core lines hot/warm? Even with a flush and fill, your heater core can become clogged. In fact, often a flush can cause your heater core to become partially clogged, then its time for a backflush.

[tokes]

They actually did a chemical flush/backflush and the both lines are hot and the system seems to be circulating just fine.

[Rick Norwood]

Originally Posted by tokes

They actually did a chemical flush/backflush and the both lines are hot and the system seems to be circulating just fine.

I have heard mention of a BLENDING DOOR that is not vacuum operated. Not sure of where it is, but possibly it is stuck and/or the fan isn't blowing air over the heater core. Other than that, I'd still say your heater core is the culprit.

[BlazerLT]

Originally Posted by tokes

I have a 1998 Blazer LT with a 4.3 liter engine, I have changed the thermostat and I had the coolant changed and a complete system flush done. I have checked the lines in and out of the heater core and they seem to be at the correct tempature. My engine temp is gauge reads a consistant 92 deg celcius. The fan blows like it should on all settings and everything seems to be functioning properly except for the lack of hot air. The A/C also works fine.

Did you reverse flush the heater core?

[Turbocpe]

Does this have the electronic climate control? Or the manual system?

[tokes]

As stated in the previous reply, I did a chemical flush/backflush of the entire system. Yes the heater core had a chemical clean and backflush done to it.

On my way home from work today the heat seemed to be working pretty good and then it suddenly went cold. I adjusted the temp control from hot to cold and then back to hot and the hot air came back. This happened a few more time before reaching home and every time the air turned cold I would turn the heat control to cold and then back to hot and the heat would return.

[tokes]

manual control

[BlazerLT]

Originally Posted by tokes

As stated in the previous reply, I did a chemical flush/backflush of the entire system. Yes the heater core had a chemical clean and backflush done to it.

On my way home from work today the heat seemed to be working pretty good and then it suddenly went cold. I adjusted the temp control from hot to cold and then back to hot and the hot air came back. This happened a few more time before reaching home and every time the air turned cold I would turn the heat control to cold and then back to hot and the heat would return.

I'm sorry, was just making sure.

Sounds like a bad temperature control or the electrical connection to the blending door is loose or the blending door itself is faulty.

[tokes]

What is the "blending door" and where is it located? I have only owned the Blazer a few monnths so I'm not real familiar with it yet.

Is there a test I can perform on my own to confirm if it's the blending door? As for the temp control I guess it's just one of those things you change out and hope for the best.

Thanks for the help, I really appreciate it.

[BlazerLT]

it is near the heater core.

[tokes]

So I found out that the place who said they did a backflush actually didn't do it. I took the Blazer to a reputable radiator company and they did a proper back flush and now I got some serious heat. I'm talking melt you shoes kinda heat....

Lessons learned.....deal with the right people and ask the right questions....

Thanks for all the advise and pointers.

[BlazerLT]

aha, so it was the heater core.

Do yourself a favor and replace the rad cap with something not AC delco and I hope you flushed your whole engine and not just the core.

All that will happen is the heater core will block up again.

[tokes]

The whole system has been flushed and now the core has been backflushed. What kind of cap should I get?

[Rick Norwood]

Originally Posted by tokes

The whole system has been flushed and now the core has been backflushed. What kind of cap should I get?

"Stant" Brand or anything else but AC Delco. I thought it was the Heater Core all along.