AC compressor & clutch dimensions

1989 XJ6 3.6 liter
Factory came with Sanden SD510 compressor (5 piston 10 cubic inch) (latter XJ40s came with SD709 compressor)
Connections on back single bolt and metal bar holding in 2 original AC hoses

Low charge caused the compressor to overheat clutch burnt out and compressor shaft is frozen.
Too bad the old SD510 did not cut OFF on low charge and has no THERMAL cut off switch to turn off an overheating compressor.

Will likely replace with a new compressor seems dicey to go with an old salvage unit… new model is SD7H15 new Sanden compressor but not sure if the mounting ears will align…

I have the dimensions for the new Sanden compressor (see PDF below) but cant find any mounting ear dimensions for the old original SD4510 model and V belt magnetic clutch

page 13 gives SD7H15 ear dimensions…

1__WIll the SD7 mount onto the old brackets for the old SD510 model?
2__Anyone have the tech dimensions of the old SD510?
3__Will new compressor SD7H15 have a thermal cutoff switch?
4__New SD7H15 has plenty of OPTIONS for the END CAP anyone have any thoughts to which one to get?
I have access to a AC hose crimping tool and could make new hoses though I don’t have the tool hoses or fittings yet.
Thanks to all,
Brad K — black and gray 1989 XJ6

And some further questions for my knowledge; my 1990 XJ40 has been converted to R134 which is somewhat less efficient than the original R12. In the event I ever need a replacement compressor is there an easy replacement that can increase the AC efficiency? Or is the limiting factor not the compressor at all but the evaporator?

John …

Actually R134a in a system designed for it is slightly MORE efficient than an R12 system. But you’re correct in stating that R134a is not as efficient as R12 in an R12 designed system.

One of the problems is the size of the condenser and the higher pressures that R134a operate at. Also R134a molecules are smaller and will slowly leak out of the hoses unless they are changed to R134a type “barrier” hoses. Additionally R12 systems use mineral oil and R134a systems use PAG (Polyalkylene Glycol) oil. These 2 oils don’t work with each other.

A properly converted R12 system will work just fine (new reciever/dryer, new hoses, new o rings, and a complete oil flush) but it’s not just a drop in replacement.

My system was converted by a Jaguar dealer per the tech service bulletin ten years ago. As I recall the PAG oil was used, a new dryer fitted and some O rings changed but no hoses were replaced. Maybe I should get the 29 year old R12 type hoses changed to barrier ones although it is still putting out cold…

John …

If your converted system is working fine, no need to change the hoses if the refrigerant loss is only about a 12oz can a year or less. It’s more cost effective to just top it off.

But remember that if you only have say 75% of the required charge you are not going to get 75% of the cooling. That’s not the way it works :smiley:

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