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98 Buick LeSabre Heating problems

I have a LeSabre that blows warm air on the floor and cold air at the window defroster. The vent blows very little air and what it does is a mix between warm and cold. After the vent is left on for 20+ mins it may start to blow a bit more air.

It used to be a little colder, I changed the thermostat with the max hottest one they make and since then the floor has gotten a little warmer.

It almost seems like the floor is bringing air from the engine and the defroster area is bringing cold air from outside. Not sure what is going on. For now I have put a towel over the vents on the window to make it tolerable. Yesterday is was a few degrees above 0 and I was not to uncomfortable. It seems like when I switch to floor mid or top defroster or a blend its blows about the same amount from the top and bottom and almost nothing mid vents. Mostly from the top defroster vents and the floor heater vent. Anyone know what this would be?

I read something saying something about a mood actuator and a temperature blend actuator on a similar problem where they only had air from the defroster. Could that be my problem and why the cold and warm air at the same time?

From what you describe, it sounds like you need one of these.

https://www.ebay.com/i/254457607119?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=254457607119&targetid=313776935016&device=c&mktype=pla&googleloc=9019498&poi=&campaignid=1669934603&mkgroupid=65058347419&rlsatarget=pla-313776935016&abcId=1123856&merchantid=6296724&gclid=EAIaIQobChMI5vLztp7D5gIVGJSzCh1kVwXdEAQYASABEgLiSPD_BwE

Tester

Not sure if this matters but mine looks like this one below. It has the style that shows the digital temp inside and out. Not sure if the other kind, cheaper, would work on mine.

Either way, it’s the brains for the HVAC system.

What are the odds of the blend/mode doors failing all at once?

Tester

thank you I will look into this

UPDATE. I was wrong on something or the warmer weather has caused it to work differently. The top drivers side blows warm air, the passenger side blows cold air and on the bottom heater is the same the drivers side blows warm and the passenger blows cooler air. I notice that temp adjuster for the passenger side is always reset to mid temp and I have to manually put it to highest level, but it seems to do little to nothing.

Is that passenger temp setting causing the problem?

HVAC Heater A/C Blend Door Actuator located inside behind glove dept. I believe that is the problem. Blows cold air on the pass side top and bottom and warm air on the drivers side and also no or little air comes in the middle vents.

UPDATE.
REPLACED THE HVAC Heater A/C Blend Door Actuator.

NOW BLOWS HOT AIR ON DRIVERS SIDE AND WARM AIR ON PASS SIDE. EVEN WHEN I PUSH THE PASSENGER CONTROL TO HOTTEST LEVEL, HAVE TO DO EVERY TIME THE CAR IS TURNED BACK ON, IT STILL DOES NOT BLOW HOT AIR.

It also does not turn to vent with put on. Basically its still blows where it wishes. But its a winter car and it has been a warm winter. If nothing else I am satisfied with the way it works now. Driving it here and there on a hot summer day with no vent air could be more bothersome.