Jim Muise

2016 Express 2500 4.8 No heat, New blend door Actuator, New blower motor Resistor, New thermostat and New heater control( not done by me). Still no FN heat. Lower radiator hose does not get hot. Haven’t flushed system yet. What else am I missing.... Please help

oilcanhenry

Well your upper radiator hose is the hose that is supposed to get hot, not the lower one. But my guess, assuming that no heat is getting into the passenger compartment, is that the valve that controls the heat has gone bad on you,.or a on your fuse or relay is not operable. Back in the day there used to be a heater control valve in the heater hose, but those are long gone these days, with all the electronic controls, ruling over the operation of newer vehicles..

mountainmanjoe

so it's blowing cold, or not blowing at all?

what is the temp of the in & out heater hoses?

@oilcanhenry
there is no separate heater valve. Coolant flow through the heater gradually increases as the thermostat opens.

oilcanhenry

Are you sure of that Mountain Man Joe? When the heater on my 1998 Chevy K-1500 is off there is no conductive heat from the heater core at all. It's stone-cold cold as can be on the climate control housing until I activate the heater controls.

Don't know about my 15" Chevy Malibu as I've never checked for that. Might be different on the newer vehicles of course.

Speaking of heaters and climate controls, the minus -30 PSI is still holding on my A/C system after three days, so I charge it up tomorrow. (I am a perfectionist with my own vehicles. ) it was a real b***ch to get that valve out of the low-side A/C charging port.

You are correct about the fact that I've never seen a heater control valve on my K-1500, but it's likely in the climate control box I am guessing, so who knows?

mountainmanjoe

My 2013 is valveless. The flow is controlled by the thermostat.
Your 1998 would have had the old simple thermostat design with no bypass. Valves were all under the hood. (and failed often)
I'm fairly sure that Jim's 2016 will have the new bypass design which gets the engine up to operating temp quicker, thus improving emissions and fuel economy.

oilcanhenry

MMJ: when my Chevy K-1500 goes in for smog, it's _way_ below the allowed limits on every level. It's not had one catalytic converter changed, nor any have any O2 sensors been replaced.in its lifetime. It's still running the original fuel pump at 22 years of age for Pete's sake. Yes, I am currently repairing the A.C system on it, as the intake port valve was leaking.after 22 years of service.

They just simply built the GMT-400 series better back then the newer models, as most of the parts.were not manufactured overseas, as in China or Taiwan.or Mexico. She was built at GM's Fort Wayne, Indiana's Full-Sized truck assembly plant in 1998 by union workers. The original paint job in Forest Green Metallic has had up well and the clutch is still original as well. You just can't beat that kind of quality with a stick these days.

Edit: I did find the heater control valve. It's in the engine compartment hidden underneath the air-cleaner hose to the throttle body. NO leaks at all but it explains why my heater never puts out heat unless I use the heater controls.

mountainmanjoe

lol no need to get defensive. I'm not judging your truck. I'm just explaining what's been changed and why.

My Astro had valves for front and rear heat. The valves were actuated by vacuum, which was in turn controlled with solenoids. They were notorious for burning out and vacuum leaks.
So if you ask me, the new system is simpler, more reliable, and gets the engine warmed up quicker.

oilcanhenry

I never meant to be defensive at all, In all these years I've never paid any attention to the heater system. except to change the coolant on time. MY apologies are extended if you believe I am mad about it. I rarely get mad, and not about something like a heater valve. Now I know something I didn't before, and I always learn from my mistakes, MMJ.

mountainmanjoe

ok glad to hear it