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GMC Forum: 2000 GMC Sierra Heater blows cold?
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Old 12-01-2010, 05:48 AM
Sham-Wow Sham-Wow is offline
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Join Date: Dec 2010
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Default 2000 GMC Sierra Heater blows cold?

My 2000 GMC Sierra blows cold air when the heat is on. Engine temp is normal 185-190.The heater core supply hose is warm/hot, the heater core return hose is cool. Is my heater core plugged or is my heater control valve stuck? By the way where is the heater control valve located? I left the truck run for about an hour,no change.
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Old 12-08-2013, 05:40 PM
HutchtheClutch HutchtheClutch is offline
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Join Date: Dec 2013
Location: California
Posts: 1

2000 GMC Sierra Extended Cab K2500

Just had the same problem. All web searches on the problem said the problem was (1) an air bubble in the Heater core that needed to be purged or (2) the temperature control door actuator needed to be replaced.

While watching a few videos on the subject I noticed this one off to the side

My owners manual detailed the "cabin air filter" but, I asked several factory mechanics about them and was told that the filter was an option that was not included in most builds. Since I didn't see it on my factory list of options I figured I did not have it.

After watching the linked video I thought that I would investigate further and found that My truck did infact have the cabin air filters. I picked up some Fram Replacements and swapped them out.

After 13 years of service the originals were PACKED with dirt and dust. I vacuumed all the residual garbage from the housing and now LOTS of warm air actually flows from the vents ! Total time for cleaning and swap was 20 minutes.
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