I have a 2010 Ford Escape Limited with a 3.0L V6, and I’m dealing with a hissing noise from the AC when it’s set to low. The sound isn’t constant; it comes and goes.
I’ve already replaced pretty much everything: the compressor, condenser, all hoses, expansion core, and valve. The system holds a vacuum, so I’m at a loss for what else could be causing the issue.
One thing I’m wondering about is the orifice tube. I’ve read that it might be relevant, but I couldn’t find any specific information about it for my car model. My friend mentioned that not all models use it, which has left me a bit confused.
Does anyone have any experience with this issue or suggestions on what I might check next? I’m hoping to sell the car soon, but I want to resolve this problem first.
TSB 14-0157
"Water getting into the heater core and evaporator core housing through the cowl may have damaged the blower motor resistor. Vehicles may exhibit abnormally high discharge and low suction pressures, erratic compressor and engine cooling fan operation, suction line frosting, and/or an excessive amount of time for the A/C system pressures to equalize after the vehicle is turned off. These symptoms can lead to a misdiagnosis of the problem as an A/C system restriction.
Your blower resistor has a dead spot that lets the air conditioner run even when the blower motor isn’t pushing air over the evaporator. The symptoms you describe are ultimately caused by it drawing air and moisture into the A/C system and pulling the low side into a vacuum.
It sounds like you’ve covered most bases already. The hissing could indeed be related to the orifice tube, which acts as a metering device in some AC systems. If your Escape has one, it could be partially clogged, causing the noise. If your model uses a thermal expansion valve (TXV) instead, it might be worth checking that component. Additionally, ensure the system isn’t overcharged, as that can also cause hissing noises. If you’re still unsure, consulting a technician who’s familiar with your vehicle’s AC system might be the best next step. Good luck!
