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Roy
Roy, import/domestic specialest
Category: Chevy
Satisfied Customers: 5603
Experience:  ASE master tech for 40 years
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I have a 2002 Chevy Astro Van 4.3L AWD. I have no Front

Customer Question

Hello, I have a 2002 Chevy Astro Van 4.3L AWD. I have no Front heat. So far, I have replaced the thermostat. Replaced the 6 way valve, replaced the Heater control solenoid?. I have checked the heater core itself for blockage by running water through it
OK. I ran the van with heat on and took off the top hose to heater core and there was no flow at all. It seems like there is either something else preventing the flow from going into the heater core. Blockage or something vacuum or electrical. Need some support
to diagnose and correct. This is Monday and I will be wanting to do the work this Saturday to correct, but I will probably need parts ahead of that. Need some diagnosis help.
Submitted: 1 year ago.
Category: Chevy
Expert:  Roy replied 1 year ago.

good afternoon my name is ***** ***** I will assist

when the van runs and is hot are both heater hoses hot?? if they are then the heater core is ok. if you have one hot and one colder, then it is clogged internally.

Roy

Customer: replied 1 year ago.
I did check the heater hoses. Both are cold. As I said earlier I did a flow check of the heater core by itself and it flowed well. Also when the van was running, I pulled off the top heater core hose. There was no flow through that hose.
Expert:  Roy replied 1 year ago.

ok, 2 possibilities, one is the water pump. it is responsible for water flow. the other is a restriction in the heater hoses.

Roy

Customer: replied 1 year ago.
Yeah, I was thinking about the water pump. This is driven by the fan belt, but can I tell if it is not working somehow? If there is a restriction in the hose, what would be the most likely hose? Also, could there be a problem with the radiator itself? I do have rear heat working, I realize it has a separate circuit, thought I would throw that in.
Expert:  Roy replied 1 year ago.

if you have rear heat, the water pump has to work. if you pull off both hoses, is there any circulation???

Roy

Customer: replied 1 year ago.
Pull both hoses from the heater core? Which way does the flow go? does it come in the bottom first and then it the top or top and then bottom? like I said, there is flow through the heater core itself. I am wanting to see where it is stopped, which item to check next. I would have suspected the 6 way valve, but I replaced this recently so I do not think it is that, but if I need to check this is there a method. this was a pain to replace that one. Also, I wanted to mention that I do have source vacuum as I pulled off the supply hose and confirmed this. The HVAC control moves the air wherever I need it. What else am I missing?
Expert:  Roy replied 1 year ago.

the hose attached to the heater control valve is the feed line to the heater core. the other is the return.

roy

Customer: replied 1 year ago.
if they both go through the valve, can I bypass this to see if I get flow?
Expert:  Roy replied 1 year ago.

yes, you need to remove the feed lines from the valve and check for flow.

Roy

Customer: replied 1 year ago.
Can you send a picture of what hoses to use for bypass?
Expert:  Roy replied 1 year ago.

I dont have a diagram but you have the 2 hoses for the front heater, 2 hoses for the rear heater and the remaining 2 are the ones you need to hook to. they will trace back to the motor.

Roy

Customer: replied 1 year ago.
Can you explain the complete path of the coolant path?
Expert:  Roy replied 1 year ago.

the water pump sends coolant to the heater control valve which distributes the coolant to the front and rear heater core. the return lines go back to the intake manifold. so you have 2 lines from the motor to the heater valve, 2 lines to the rear heater and 2 to the front heater.

Roy

Customer: replied 1 year ago.
Grand river closed howell
Customer: replied 1 year ago.
Sorry don't answer that.
Customer: replied 1 year ago.
Where is the radiator in the process? Could you tell me the entire path?
Expert:  Roy replied 1 year ago.

lower hose to pump, pump out to the heaters and the block up to the thermostat and back to the radiator.

Customer: replied 1 year ago.
what would be the best way to test this? Can I bypass the 6 way valve with some connectors and just isolate the front heater core? How would be the best way to do this?
Expert:  Roy replied 1 year ago.

you need to take the hoses from the motor off the heater valve and use joiners to the front heater core. you can get the joiners at a parts store.

Roy

Customer: replied 1 year ago.
Thanks, ***** ***** going to try this. I will let you know how this works. I may have more questions. Stay tuned
Expert:  Roy replied 1 year ago.

ok

Customer: replied 1 year ago.
If I am getting rear heat that means my thermostat is working correct?
Expert:  Roy replied 1 year ago.

that is correct

Roy