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Heat & defrost issues


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I have a 2007.5 Lmm GMC 3500. When I start my truck in the morning most of the time my heat won’t work and my defrost won’t work. No matter what setting I try to put it too it’ll only blow cold air out of the regular vents. Sometimes later in the day when I start it I won’t have this issue anymore. What should I look for? Thanks 

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At the very least your Mode Actuator probably needs replacing.  All four of my actuators have thrown codes and three have been replaced so far up front.  Our rigs are getting old!

 

I learned today from my daughter, that the Foseal OBDII adapter I gave her can read BCM codes with the Apple Car Scanner app.  If you can access the BCM codes, they will tell you right away what's wrong.

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6 hours ago, swathdiver said:

At the very least your Mode Actuator probably needs replacing.  All four of my actuators have thrown codes and three have been replaced so far up front.  Our rigs are getting old!

 

I learned today from my daughter, that the Foseal OBDII adapter I gave her can read BCM codes with the Apple Car Scanner app.  If you can access the BCM codes, they will tell you right away what's wrong.

I will check that out. Thanks 

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