Not getting any heat in cabin

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Camperbob

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I have been fighting this problem for a little while now on my 2003 expy trying to figure out why I am not getting any cabin heat from either heater core. I have read a number of posts and performed a number of tests. I get a little bit of slightly warm air at times. I do not have any clicking in the cabin so I have ruled out the blend door actuator. I rigged up a Compressed Air connection and blew out the front Heater Core. Neither heater cable is getting very hot. The restrictor for this system is in the intake hose just after the front manifold connection. I visually checked it and it is open. I don't have any issues with overheating in the summer so I don't think the fins on the Water pump are bad. I replaced the Thermostat. I have manually opened the valve on the inlet heater hose with my hand but it made no difference. I figure I have to have a blockage somewhere, but just don't know where to look next or if I am even on the right path. The return hose tees off just after the front heater core and actually runs down behind the firewall. Not sure how it routes around back to the water pump.

Any help on this would be appreciated.
Thanks
 

Habbibie

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could you possibly have an air bubble in the coolant system? With the heater core being the highest part of the cooling system air might be trapped inside.

Some cars have a bleeder valve for the air, some do the parking on an incline so the heater core is no longer the highest part of the cooling system and either open up the radiator cap or something of that nature...

Can you verify if theres coolant in the radiator and that it's full to the brim? Do you have a radiator cap or only the resviour has a cap?
 
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Camperbob

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I have actually drained the fluid a few times of the last year trying to get to the bottom of this problem. The last time I drained it I installed one of those Prestone Flush and Fill adapters into the return side heater hose. I allowed me to hook a air connection up to blow out the heater core. After refilling the coolant I verified that coolant was indeed traveling through the circuit. I have also done the trick of parking on an incline and running the heat after refilling the coolant.
 

Trainmaster

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If you haven't got a bubble in the system, the thermostat is correct and the heater core is full, the heater core is restricted and should be changed or you have a head gasket leak that's causing the fluid level to leak down.

Pressure test the cooling system to assure it's not a head gasket problem. Or pull the hoses and loop them to see if they heat up and you have good flow.

With what you're saying, I'd bet on the heater core.
 
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Camperbob

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Update. I disconnected the intake heater hose at the front manifold and blew out the line into the manifold until water started coming out of the hose. I then hooked it back up. After that I manually manipulated the built in valve in the intake a little bit and started getting heat. Not sure what step actually fixed it.
 

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