1. Leak in your A/C line, kaya biglang nawala ang lamig malamang ubos na ang freon. My primary suspect is your evaporator.
2. One probable cause is the vaccum switch which automatically adjusts rpm when compressor is charging. Another case is an IC inside your hood (which I forgot what that name is), that controls your engine's rpm if it's an EFI.
3. Sunong na motor, pinapalitan ng either surplus or brand new motor.
Dalhin mo sa mga aircon experts they know what to do, expect to shell out 3-5K for an evaporator, 800 freon refill, blower cleaning, fan motor is around 350 for surplus to 800 for a rebuild unit. And other plus plus...
Dinala ko kanina sa Sprint sa may shaw tapat ng cherry fudurama.
Una akala nila sira yung "magnetic wire daw" also known as compressor clutch. May short daw, kasi pag pinapalitan yung fuse nasisira kaagad, nung kinakalas na nakita nung repairman na may wire na naipit sa itaas ng compressor inayos lang yung wire and palit ng fuse, ok na. Buti nalang yun lang =)