edit (changed Model Year to 2003 misread the Vin XD
This is one of the strangest things I have ever encountered. when i start my car the climate control system works perfectly and it never has any issues driving around town. however for the past year or so every time i take a long drive over an hour and a half the force of the air coming out of the vents starts to diminish to the point where the only circulation i am getting is from the outside vent. the strange thing is i can hear the fan blowing behind the dashboard and when i hold my hand to the vent the air coming out if very cold / hot depending on where i set the dial so it doesent appear to be an issue with the AC or heater core .
I am thinking there might be some type of obstruction but that doesent explain why the symptoms occur like clockwork on long drives.
I am hoping someone can shed light on this i am bringing my car in for servicing soon and need to be armed with information so they don’t try to sell me a whole new climate control
Offhand, I might suspect the A/C evaporator is icing up. Once it starts thawing out airflow increases.
The evaporator freezing up can have a number of causes but the first thing I would look at would be the A/C system pressures at elevated RPMs (say about 1800)
Sometimes a little refrigerant loss over time can drop the low side pressure to a certain point combined with humidity in the air and turn the evaporator into a block of ice.
Next time it does this take a quick look underneath the passenger side of the car about where a passenger’s feet would rest and note if there is a normal condensation drip from the evaporator.
Hope that helps.
If it was icing up wouldn’t turning off the ac and moving the temperature dial to the middle restore the air flow or does the air always pass over the evaporator
also if there is a refrigerant leak how much does that usually cost to patch?
Air should always pass through the evaporator. That’s how you get defrost…through the evaporator and the heater core. There might be a thermistor to cut off the compressor to prevent icing (like in my Hondas).
I am not sure, but seems your re-circulate gate is somehow closing with long drives. The motor should be behind the glove compartment. I had a '95 with very similar set-up and my vent motor/gate would click and not open. I changed the motor and all was fine. Funny thing is I was buying my part from a junkyard that was also restoring a few of these cars to re-sell and the guy had the same problem on one of the “fixed” cars. He was so happy that I showed him where the problem was that he gave me the part for free.
