99 Sierra has no heat

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99 Sierra has no heat

Unread post by Dan » Thu Aug 27, 2015 10:47 pm

99 Sierra pickup has no heat.
I flushed the heater coil and have hot water both sides.
Fuse is ok.
Blower and control for vents, defrost works ok.
Turning the cold to hot control, temp stays the same, although it sounds like something is moving, but not certain what the noise may be.
Just for info, the instrument cluster needs to be replaced, but I can't see where that could be related.

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Re: 99 Sierra has no heat

Unread post by carriedi » Fri Aug 28, 2015 8:50 am

you should take off the air temp door motor and see if you can change the temperature by moving the door manually.the motor could be bad, the door could be stuck or the door could be broken.
air temp door motor.jpg
air temp door motor.jpg (74.85 KiB) Viewed 1989 times
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