2008 Ford Focus AC Cycle At High RPM
Posted in Air Conditioning | Asked on Jan 28, 2012
I have a 2008 Ford Focus that when at idle the ac compressor runs constant with a steady low side pressure of 50PSI at an ambient temperature of about 90-95 degrees. It is ice cold at idle, but as soon as I get it above 2500rpm on the highway, it starts cycling on and off. Is this a refrigerant problem, or could it be the pressure sensor on the car? Regardless of outside ambient air temperature, it tends to cycle under a high RPM. I have read that this is a normal function of some Fords, but I am not buying it. Opinions anyone?
There are 3 Answers
DON”T buy a DIY refrigerant kit, they’re worthless, You belong in a certified A/C shop if you want to save time and money.
Might be low in freon, though, if fan speed is low, it will cycle off and on
This is normal. The Focus, along with many Fords, uses a fixed orifice tube, rather than an variable expansion valve to meter the flow of refrigerant. The AC is designed to cycle to keep the Evaporator from freezing. Cycling the compressor is how the AC controls the flow of refrigerant through the system. At idle, the compressor spins just fast enough to keep a constant flow of refrigerant without freezing the evaporator (blower on high), but off idle the Compressor pumps more refrigerant than needed, so the engine computer cycles the compressor to prevent evaporator icing.