I’ve been having a vexing problem on my 2001 LS with 160,680 miles. I’ve had several winters where I’ve had little to no heat. What’s weird is that when it’s warm (50+), my heat is usually pretty good (not as good as it should be though). When it drops into the 30’s and below, it’s anemic and sometimes is absolutely zero.
Things that have been done to the car that relate to the HVAC system recently:
Flushed heater core several times (mostly clean, no rust and good flow) - hoses are warm (not hot like radiator hoses) Replaced top Quick-Lock hose connector to heater core (old one cracked when taking off hose) New water pump (changed at 158k miles a month ago) - new GM rotor vane style New serpentine belt (Goodyear Gator) New radiator hoses New s-bend hose at top engine by bleeder valve Checked for air in system at bleeder valve Thermostat changed at 60k miles during intake manifold gasket change Flush of system (twice over the last 3 years) - filled with DexCool
If I do get any heat, it’s only when I’m on low fan, and maybe an outlet temp of 60-65. At higher fan speeds, the heat is sucked out of the heater core faster than it goes in so it blows cold.
I visually checked the heater blend door actuator and it’s working (at least the shaft is turning - I didn’t remove it).
One odd symptom is that when the heater knob is all the way on hot, the air flow is about 1/2 that when it’s all the way on cold (one reason I checked the actuator).
Of note, first time I noticed it was when I had a flush at 100k miles (done by a mechanic at work). I checked for air in the system and also flushed my heater core and it got better for a bit.
This is really no fun. I live in the northeast and when it’s 10 degrees out, it’s like driving a freezer to work (45 minutes). Driving to VA last weekend was even worse - 6 hours with it being about 45 degrees in the car.
Help heat me up! Thanks.