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2014 GL450. I have a weird issue with heat. On auto setting with both driver and passenger set to the highest heat level, the drivers side floor duct blows out pretty warm air. Passenger side is cool. If I change the heat direction to vents, the vent closest to the drivers side window is warm, the vent on driver side near radio is a little warm and passenger vents are both cool. If I rev the engine or drive on the highway all vents get a little warmer. I have flushed the coolant system. I have check the temp on both sides of thermostat and they are equally hot. It seems all hoses under the hood get warm. Fan blows strong. AC works well. No leaks of coolant that I have found. Any ideas?
Had a dealer look at it and it is the HVAC Heater Blend Door Actuator or the heater core. Quoted 20 to 25 hours of work because the entire dash has to come out and $600 in parts. Pretty nasty cost for a car with 70,000 miles. Not to mention the other issues Tailgate lift fail, blown rear suspension airbag.
I’m an advanced DIY’er. Took me a full day to tear down and another full day to put back together. I did the tear down one weekend and the put-back the next weekend to give me a break in between. It’s all about being meticulous, labeling everything, and following the steps exactly as laid out in WIS.
I would never paid a dealership to do this out of warranty. Sell the car first. Either DIY the job or take it to an Indy shop.
Oh, and the blown rear suspension airbags are exactly the opposite... SUPER easy! I did both of mine last weekend at 115k mi. Start to finish was about 45 minutes. Very simple DIY job. I got the Arnott brand bags. Half the price of OEM and great quality. Stay away from the other aftermarket brands that are even cheaper, they have bad reviews.
Just thought I'd bump this old thread, because I ran across it in trying to get a handle on my similar problem and it scared the hell out of me. Had the same symptom, pass side cold, driver side warm (but not hot), based on this thread thought I was looking at a new heater core at 68k miles (2014 GL 450). Turned out a simple flush of the heater core completely resolved it, at least for the time being. Just fyi, it's not necessarily a complete teardown of the dashboard, try the simple stuff first.
Just thought I'd bump this old thread, because I ran across it in trying to get a handle on my similar problem and it scared the hell out of me. Had the same symptom, pass side cold, driver side warm (but not hot), based on this thread thought I was looking at a new heater core at 68k miles (2014 GL 450). Turned out a simple flush of the heater core completely resolved it, at least for the time being. Just fyi, it's not necessarily a complete teardown of the dashboard, try the simple stuff first.
Thanks for this. I'll try this. I have the same exact problem.
By all means try a back flush first! Disconnect the inlet and outlet hoses at the firewall and get some tubing and valves from Home Depot to connect a garden hose and regulate flow and pressure. Be careful with the pressure as depending on your area water pressure may be 50-65 psi and could rupture the core. Reduce pressure to about 10-12 psi. I tried and did not work, but my core was severely plugged. I cut it open with a sawzall after I got it out and it was caked solid. Hopefully you have better luck.
2014 GL450. I have a weird issue with heat. On auto setting with both driver and passenger set to the highest heat level, the drivers side floor duct blows out pretty warm air. Passenger side is cool. If I change the heat direction to vents, the vent closest to the drivers side window is warm, the vent on driver side near radio is a little warm and passenger vents are both cool. If I rev the engine or drive on the highway all vents get a little warmer. I have flushed the coolant system. I have check the temp on both sides of thermostat and they are equally hot. It seems all hoses under the hood get warm. Fan blows strong. AC works well. No leaks of coolant that I have found. Any ideas?
Hello, I know this is couple year old thread but wondering if you get to a resolution with this issue?
10-27-2020, 01:38 PM
