1998 Blazer - no heat


tokes
02-14-2005, 10:25 AM
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
02-14-2005, 12:35 PM
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
02-14-2005, 12:41 PM
They actually did a chemical flush/backflush and the both lines are hot and the system seems to be circulating just fine.

Rick Norwood
02-14-2005, 02:00 PM
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. :naughty:

BlazerLT
02-14-2005, 10:09 PM
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
02-14-2005, 10:11 PM
Does this have the electronic climate control? Or the manual system?

tokes
02-14-2005, 11:50 PM
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
02-14-2005, 11:52 PM
manual control

BlazerLT
02-15-2005, 12:42 AM
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
02-15-2005, 09:03 AM
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
02-15-2005, 03:38 PM
it is near the heater core.

tokes
02-17-2005, 12:40 PM
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
02-17-2005, 04:10 PM
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
02-17-2005, 04:16 PM
The whole system has been flushed and now the core has been backflushed. What kind of cap should I get?

Rick Norwood
02-17-2005, 04:21 PM
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.:naughty:

BlazerLT
02-17-2005, 04:40 PM
"Stant" Brand or anything else but AC Delco. I thought it was the Heater Core all along.:naughty:

Yip, Stant is the best.

Also, I made the mistake about the heater core too, seeing it was flushed I thought they did the job right.

Guess I shouldn't assume this from now on.

Rick Norwood
02-18-2005, 12:11 AM
Yip, Stant is the best.

Also, I made the mistake about the heater core too, seeing it was flushed I thought they did the job right.

Guess I shouldn't assume this from now on.

I agree, you know what they say about the word "Assume"! I still swear by my Do it yourself Garden Hose Flush, next to a reverse power flush, you can't beat it! :smokin:

chcknugget
02-18-2005, 12:18 AM
I agree, you know what they say about the word "Assume"! I still swear by my Do it yourself Garden Hose Flush, next to a reverse power flush, you can't beat it! :smokin:

I know, I flushed mine at a car wash and it really did the trick... Thank goodness!

I plan on doing a proper flush when it heats up outside.

bjaymo3
02-23-2005, 03:25 AM
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.

I had/have the same problem. I went to my mechanic who was going to flush it but found that I was more than a gallon short of coolant. He added coolant to normal level and heater worked fine.........for about 3 weeks. Just today, I had the problem re-occur and found my coolant level very low once again. I do not find coolant in the driveway so I'm wondering where it's going??

BlazerLT
02-23-2005, 03:27 AM
Check your oil and see if it is mily white from coolant.

Also, install a new rad cap.

bjaymo3
02-23-2005, 06:44 PM
Check your oil and see if it is mily white from coolant.

Also, install a new rad cap.

The oil is fine. I replaced the rad cap as you suggested. Now, I'll just hide and watch.

Thanks for tips!

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