Then I looked up the AC test section of the service manual and decided to give it a try. Before I could begin though, I wanted to investigate why the vent selector no longer worked. It’s been broken for years and I just left it because the thought of pulling the dash was overwhelming. Turns out all this time the broken part was just next to my foot, and I quickly found the servo and pulled it out of the car.
I tore it down to find that the DC motor inside had a dead spot, but everything else was fine. I tested the motor a few times, cleaned the gears, added new silicone grease, and put it back together.
For a few beautiful seconds I played with the dash buttons and the servo dutifully switched vents… Until it hit the motor’s dead spot again and ceased responding. Oh well, re-winding a motor coil is where I draw the line, so I manually turned the dash vents to the setting for the AC test and proceeded.
… But I didn’t have a thermometer… And the local grocery store didn’t either! Frustrated with the lost time, I pulled out my trusty AMT1001 and made my own thermometer/hygrometer rig.
I jerry rigged up some old gauges to the AC refrigerant lines and then carried out the 10 minute test. At the conclusion I wrote down the results, and then blindly tried filling out the AC chart to the best of my ability.
|High side pressure||195 – 220 psi|
|Low side pressure||13 – 39 psi|
|Ambient Temperature||20 C|
|Vent Temperature||8 C|
|Ambient Humidity||20 %|
|Vent Humidity||49 %|
I’m not sure how to interpret the results, but was surprised to see the temperature actually drop and stay there. I’ve suspected something is wrong with the AC for a long time now, because usually it will blow cold for a few minutes and then give up.