mlkmgr

It was the actuator. Got it all hooked up and now switches between hot n cold air. Anyone help on which connectors go to the power outlets in the dash? Putting it back together but no more power.

Quick update. Heater blend door actuator not working. Going to get new part. Can manually turn door and have heat. If actuator not the problem, then it has to be hvac controls. Will follow up.

Have a 98 Sierra 5.7L and heat stopped working the other day. Vents blow on all speeds but only cold air. -coolant is full with no bubbles coming out when rad cap is off BUT also looks like fluid is motionless (maybe lack of circulation?) -upper radiator hose warm to touch. Can hold for quite awhile. -lower radiator hose cold. -lines in/out of heater core very hot (can only hold a few seconds). -temp gauge holding steady just below half way mark. -assumption is HVAC controls work but cannot verify. All functions appear to work. -no difference in heat if truck is in motion or sitting idling. I cannot locate blend door actuator nor hear it when switching between hot/cold on HVAC controls. Any help or suggestions would be greatly appreciated!!

Just to close this out...code was P0174 only with the occassional flashing engine light (P0300) when i accelerated hard. Changed plugs, plug wires, fuel filter, cleaned MAF, and the upstream O2 sensor on passenger side. See the pic but this thing was caked in black soot also. Idk when the last time any of the O2 sensors were changed but this definitely was bad. Going to order the remaining 3 and swap em out to be safe. Can accelerate without issues, no engine shake, and all is good again.

Sorry I typed the wrong number which I know changes everything.......the code i P0174!! Fuel Trim System Lean Bank 2

My scanner shows short n long term fuel trims. Just not sure what to look for or how to interpret reading. Would this b what i am after?

Any way to be certain? Guy has limited funding to fix this and he cant afford to throw money at parts. Thanks for the reply!

Have a 2003 Silverado LS with 5.3 @ 149K miles. Engine running sluggish and flashes check engine light once you try to accelerate above 50mph. Pulled codes. P0174 and P0300 r codes. Changed plugs, wires, and fuel filter. No change. Plugs on passenger bank all black and sooty (see image). Drivers side showed sm wear but nothing like bank 2. Fuel is 48psi idling and bumps to 53psi when revving. Fuel pressure regulator is not leaking and shows no sign of wetness anywhere in hose connected. Reading all over web about possibilities from fuel pump to upper intake gasket to EGR to MAF. But those are all usually accompanied with P0171 also. Any thoughts??