Hey guys, I'm Troy.
I just bought a 2010 MKS Ecoboost a couple weeks ago with 27k miles and I've been trying to get it into tip-top shape. Unfortunately, it's already had a few problems I've had to address (first, clogged sunroof drains resulting in flooding and subsequent sunroof motor failure, rear window regulator failure, and then the apparently notorious blend door actuators [recirc and driver blend]) .
Now that those are all taken care of, the heat is setting in and I'm realizing the A/C compressor is not staying on. Sometimes it works more or less okay, and when the compressor is on, the air is nice and cold, but other times the compressor comes on for about 1 second, and then stays off for 9 seconds, and repeats. Obviously this is basically worthless for cooling the car, so I'm trying to figure out what the deal is. The system has a good charge and runs around 45 psi at 80 degrees ambient on the low side when the compressor is engaged, so I think I'm looking at a bad sensor.
After digging around, I found some threads on a Flex forum about bad evaporator temp sensors and a TSB applying to 2009 MKS', but not 2010. I'm inclined to think this temp sensor or one of the pressure sensors is bad.
What sensors does this car have that control when the compressor is engaged? High, low, and evap temp? Are there any common issues I should be looking for? Are there any diagnostic HVAC modes I can access or test procedures available? Like I said, if I could get the compressor to stay on, it would cool the car just fine, but as it is, the <10% duty cycle is pretty worthless.
