kung may separate switch yan A/C mo yun muna pa check mo... secondary switch lang kasi yung thermostat... as i have said sa setup ng kotse ko.. kahit naka manual t-stat ako eh controlled pa din ng ECU yung A/C... although i have a separate switch for the A/C the relay for the compressor is still controlled by the ECU so pag na sense nung ECU na nahihirapan yung engine ko momentarily switch-off nya yung A/C to allow the engine build up power...

also have the pressure switch (located sa drier or near the drier) checked... nag ice yan A/C mo kasi hindi nag automatic cut off yung compressor plus madumi na yung cooling coil mo kaya nag stay yung tubig in between the fins na nag ice kapag sobra na lamig... actually pag nag ice yan mawawala ang lamig sa air vents kasi na block nung ice yung daanan ng hangin