2000 Other Isuzu Models HEATER CORE HOSES STAYING HOT

MCAUTODOC

MEMBER
2000 ISUZU
V8
2WD
AUTOMATIC
162,000 MILES

VIN #4KLC4B1R6YJ805937 / 2000 Isuzu NPR delivery truck.

Did some a/c work and noticed the hoses going to the heater core were the same temp ( approx. 155 deg) with the dash valve set all the way to cold and in recirculation mode. I identified the hose coming out of the water pump as the supply to the core and clamped it off; within a couple min the temps had come down to around 95-100 deg on both hoses and decreased the a/c vent temp a couple degrees. Anyone have a diagram showing the vent/dash controls for the HVAC system on this truck? Would like to have something to check out before I go taking the dash off to see what the problem is.

1 Reply

MERLIN2021

MECHANIC
17,250 POSTS

Sorry I don't have any diagrams for it, but if the A/C compressor is working, and charge is full, the temperature blend door is binding or the actuator /cable to it is defective, heater hoses should be hot! Heat is turned off by the temp blend door for a/c! This is inside the heater plenum assy.