My heater is blowing cold air, I have done a radiator flush, replaced
fluids, replaced thermostat. Still no heat. Checked the top radiator
hose and also the heater core hoses could not feel much liquids going
through or any at all. Could the water pump not be pumping enough?
Any help would really be appreciated.

blazer99 wrote:
If the engine is running normally, it's most likely one of the "doors"
in the ventilation system. The one that moves to allow more of less air
to blow across the heater core is the mostly likely culprit. See if the
actuator is trying to move it. It might be a fuse or the control head.
If your water pump was not working properly you would have other issues.

In article
<61042fdb-51b7-4a4a-8a12-f61de6402f8d (AT) f40g2000pri (DOT) googlegroups.com>,
blazer99 <rcano99 (AT) gmail (DOT) com> wrote:

The heater core is plugged.

Go to the FLAPS and buy (two) 5/8" x 3/4" heater hose adaptors and (one)
each 6" length of 5/8" and 3/4" heater hose (two) #10 hose clamps,
(two) #12 hose clamps.
Put one 6" length of heater hose on each adaptor.
Disconnect the heater hoses from the heater core, using the new hose
clamps, install the adaptor/hose assemblies in between the heater hoses
and the core so that the hoses are now reversed from their original
position. This will reverse the flow thru the heater core.
Drive the truck. Higher RPM will help dislodge the blockage. You should
begin to feel hotter temperature from the heater.
Restore the heater hoses to their original positions.
(time spent so far should be no more than 20 minutes)

Repeat the radiator flush procedure making sure that you open the block
drains to allow all crud to exit the block.

I've had 100% success with this procedure.

The core is plugging because there may be air intrusion into the cooling
system, check the intake manifold gaskets and make sure that you are
using the updated radiator cap per GM TSB, if the radiator cap you have
now is the black plastic one the truck came with originally, it's the
wrong one.
Overflow bottle should be cold filled to the "HOT" level.

If the water pump was defective, the truck would over heat. Do the smaller
hoses to the heater core remain cold, even after the truck is driven?

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"blazer99" <rcano99 (AT) gmail (DOT) com> wrote

My heater is blowing cold air, I have done a radiator flush, replaced
fluids, replaced thermostat. Still no heat. Checked the top radiator
hose and also the heater core hoses could not feel much liquids going
through or any at all. Could the water pump not be pumping enough?
Any help would really be appreciated.