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Discussion Starter · #1 ·
Anybody had this problem ?
My heater will not operate unless on max heat setting for about 30 minutes. After that it operates as normal.
There are no faults stored and it passes the function test fine. The heater matrix is not blocked obviously and the coolant is correct.
 

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Dallas, Texas
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Anybody had this problem ?
My heater will not operate unless on max heat setting for about 30 minutes. After that it operates as normal.
There are no faults stored and it passes the function test fine. The heater matrix is not blocked obviously and the coolant is correct.
Connect scanner. Read temperature sensor vales from AAC, engine, transmission. First reading with vehicle after overnight rest. All sensor values should be about the same. +/-3F.

Now, unless you have vehicle with electric heater booster don't expect heat until engine temperature gets up there.
 

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Discussion Starter · #3 ·
Thanks for the reply.
All sensors OK.
Engine at NOT in 5 Minutes. No control of cabin temperature for about 30 minutes. Then system operates normally.
Heat on max setting. No heat on lower settings. This applies to both temp controls. Strange.
 

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Check circulation pump. If it is open or shorted it will set a fault. But if it just sits there doing nothing you will get delay in heating.
 

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