Camperbob
New Member
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
Any help on this would be appreciated.
Thanks