I had a the same issue on my 2002 Nissan Altima. The only thing that worked for me was to install a dedicated water pump for the heater. A DIY kit can be found at amazon by searching for vehicle heat pump.
I had a the same issue on my 2002 Nissan Altima. The only thing that worked for me was to install a dedicated water pump for the heater. A DIY kit can be found at amazon by searching for vehicle heat pump.