2006 Mercury Marquis atc malfunction

[quote:bab803d6f5="SkinnyVinny"]Air Conditioning problem
2006 Mercury Marquis V8 Two Wheel Drive Automatic 93000 miles

When the AC compressor engages, engine RPM drops about 250. No cool air comes from the vents, only defroster and floor openings. Lately, there is no condensate on the driveway after 5 minutes of AC in ON position in 78º climate, PLUS the engine cooling fan is not operational AND the engine overheats so I had to turn it off when it reached high and the warning light came on in addition to the gauge reading at the highest level. All this latter sequence happened within about 5-6 minutes of idle in Park.[/quote:bab803d6f5]

Hello, It sounds like you could have multiple problems, First the engine should automatically adjust the idle, so check the idle air control motor, and check for vacuum leaks.

https://www.2carpros.com/first_things/why_does_my_engine_idle_low.htm

Next the vent operation, go here:


https://www.2carpros.com/first_things/why_does_my_vents_stay_on_defrost.htm

Engine overheating engine


https://www.2carpros.com/first_things/engine_over_heats.htm


and finally:


https://www.2carpros.com/first_things/air_conditioner_not_working.htm


Once these basics are covered please get back to me so we can continue. Thanks for using 2carpros.com