Looking for a heater / a/c climate controle switch for a 89 ford tempo, all local stores wont carry and when im online it says the part never existed, so i guess i need the actual name and ford pa

Sometimes you have to bite the bullet and go to the Dealer. The Dealer has a book called an OSI book. Obsolete, Superceded, and Interchange are the way it is organized.

For used parts try Carparts.com. For a better understanding of Ford parts-they carry 2 types of part numbers. There is a Service number and an Engineering number.

The Service number is the over-the counter part number. The part numbers have a middle BASE number and the numbers and letters before the BASE number are Prefixes. The Prefix tells the Year and Model of vehicle. If a part is a D8AZ it is for a 1978 full size Ford, a D9 is for a 1979 full size. A D8MY is for a full size Mercury, D8LY is for a Lincoln.

These first numbers can be important, but if they interchange there are 2 things to know. A Ford part is usually cheaper than a Lincoln part and you can't go by the Prefix. That is why the BASE number is referenced. This is not to say the Suffix is not important, as the suffix can notate Engineering changes when looking at an Engineering number.

For instance, The first run part has an "A" Engineering suffix. Improvements could end with "B" or "AA". Perhaps the "A" suffix fits only the Mercury, but a modified "B" or "AA" could fit both Mercury and Ford sister cars.

This is why you need to know what each part of the Engineering number means.or have the Service number. Ford usually stamps or labels, or moulds only the engineering number on components.