1998 Chevrolet Blazer No Heat

1998 CHEVROLET TRAILBLAZER
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ALSAM
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I just had my altenator replaced and after work was completed I have no heat...could there be any correlation? Also, if it is just coinciental, how do I determine if it is the thermostat or something else like computer ???? When the enjine is warmed up and you turn on the heat blower you get a second or two of warm air and after that cool air. Any help is appreciated.
Jan 21, 2007 at 1:05 AM
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SERVICE WRITER
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I don't see a relationship. First thought is make sure the coolant level is full. Second thought is a plugged heater core. Backflushing may help if this is the case.
How hot are the hoses at the heater core?
Jan 21, 2007 at 1:16 AM
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ALSAM
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Thanks for the reply. Coolant level is fine. Don't know the exact temp...I'm not the mechanic, a friend is looking at it. He said, I believe, that the top hose was hot and the bottom cool. Also, I recently had the radiator flushed (last month) and a thermostat was replaced in 04. Should I have it flushed again?
alsam
Jan 21, 2007 at 5:25 AM
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SERVICE WRITER
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The hose conditions further condemn the heater core. 2 solutions that I see are: replace the heater core or try to BACK flush it. When you back flush a heater core, you take of the two hose going into it and run water through the core reverse it's normal flow. Sometime this doesn't work and replacement it the only way.
Jan 21, 2007 at 10:43 AM
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ALSAM
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Ill give it a try. Thank you for the help.
alsam
Jan 21, 2007 at 11:34 AM

Suggested Repair

Confirm coolant is full, then backflush the heater core by disconnecting both hoses and running water through it opposite normal flow. If that does not restore heat, replace the heater core. The hot upper hose and cool lower hose point to a restricted core, not the alternator or computer.

Conversation Summary

A 1998 Chevrolet Blazer lost heat after an alternator replacement: the blower briefly blows warm air, then cool air. Coolant level is fine, the upper heater hose is hot, and the lower hose is cool. The expert sees no link to the alternator and recommends backflushing the heater core or replacing it if flushing fails.

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