2013 four door 2.8L diesel (no-turbo), 4x4, manual, made in Thailand, sold in Indonesia (no heat in climate controls).
I am having trouble figuring out my air-conditioning and the auto repair people at the small-town Mitsubishi service center and private repair shops are not very helpful. We have confirmed the compressor is engaging, the condenser is clean, and the coolant is charged.
When I first start the vehicle the AC blows strong and cold, the wind on 3 or 4 easily felt from 30-40cm away. After about 15 minutes the air flow out of the vents is greatly reduced, even at 3 and 4 it is barely felt from 10cm away. However, the blower seems to be working just as hard, which I have confirmed with a multimeter clamp on the blower wires, it's pulling about 12 amps on speed 4 whether earlier when the air is strong out of the vents or later when it is hardly felt. Output from dash and floor vents is similarly weak, fresh and recirc.
If the vehicle has not been used, then I start it with only the fan blowing and AC turned off, the strength of the airflow out of the vents remains strong for at least the 30 minutes I tested this.
One mechanic suggested the interior ambient air sensor is often a problem, and I have ordered one to try that, but I have confirmed that neither the compressor nor blower is turning off.
So my question is, is there any physical diversion on obstruction mechanism in the ventilation system which could be causing this based on faulty sensors?
My other suspicion is that perhaps all the air must go through the evaporator and perhaps it is icing up and all but stopping the airflow?
If anyone has experience with a problem like this, or has opened their ventilation system, or has schematics of the ventilation system, your insight would be greatly appreciated.