Started some time in the winter. The heater started blowing air that felt like the air outside. Fortunately the winter was coming to an end and it wasn't a pressing matter, but as the weather warmed up and I began to use the AC, I got the same air I was getting with the heater.
Some notes about operation, and what I've checked thus far:
-Engine runs at normal operating temperature. Comes up to temperature quickly and NEVER overheats (thus ruling out thermostat).
-Both hoses going from the Heater Core through the firewall heat up normally.
-Compressor engages correctly when AC is on max.
-Both high and low pressure readings were normal; refrigerant and anti-freeze are both clean and full.
-Recently performed radiator flush & fill.
-Used the UV crap to locate leaks. Found none.
-Air blows normally from all ducts, and responds to adjustments in fan speed.
-This particular Taurus has the automated/push-button temperature control, not the dials.
My last 3 oil changes and tire rotations were performed at 3 different garages (on purpose). I had all 3 run diagnostics, and none pulled any codes. Each suggested completely different solutions, but none were different than the ones I, or someone else had already ruled out.
I am getting exceedingly frustrated. I have to drive long distances on occasion, sometimes with my two very young children, and I hate trying to improvise climate control. I also have no interest in letting some mechanic tear apart my dash for 6 hours, charge me $800, and then potentially not fix the problem or find it could have been much simpler.
I have yet to find anyone who can explain why both the heater and AC blow the same air, despite them being independent units.
Can anyone help?!?! Thank you!