My 1989 XJS still has a dead climate control. my question is ; is the number 36900200 on the ECU a jaguar number and is there anther ECU number that will work.

 

Not a Jaguar number, the Jaguar part number for the ECU depends on your VIN, it's part #1 in the list here: https://parts.jaguarlandroverclassic.../brand/jaguar/

The ECU's in an XJ40 sedan look very similar, but have different part numbers. I suspect the number you are seeing in a Delanair number, as that's the company that made the climate control system. If it's completely dead, replace fuse #11 as a start. The lucas glass fuses can sometime look ok, but not actually conduct sufficiently to work.

 

Not a Jaguar part number. It is probably a serial number or model number, of significance to whoever manufactured the module for Jaguar.

If the last 6 digits of your VIN are 179736 or lower, and I suspect so, the choices are pretty simple.

If you have a red water temperature switch the module is JLM763
If you have a black water temperature switch the module is JLM2121

The water temp switch is under the dash, LH side, located on one of the pipes leading to the heater core. You'll probably have to remove the under-dash trim panel to get a peek at it.

I don't know for sure what the difference is between them so I don't know how well, if at all, they'd interchange. It might have something to do with coupe versus convertible.

Cheers
DD