> My van has been to the shop several times in the last six weeks for the
> same problem. The heater blows cold air when idleing. The engine is hot,
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> only flows when the engine is running at a high rpm. Is the water pump
> supposed to circulate at an idle???
Absolutely. I am assuming that this vehicle has an engine driven fan,
can you "wobble" the fan? If so then definitely replace the water
pump. I would replace it anyway; the water pump for a Chevy engine is
cheap and it sounds like you may have an impeller that is slipping or
falling apart. I would take the back cover off of the water pump when
you get it off the engine to see if there is a problem in there; if you
find it then you can be confident that you've fixed the issue by
replacing the water pump.
good luck,
nate