The aftermarket parallel-flow condenser that I installed a few months ago in my car is a drop-in replacement for the stock condenser. However, this is currently only available for 5-speed cars '87 and newer. The automatic cars have a smaller condenser due to the ATF cooler across the top in front of the radiator. Like I mentioned before, since the 928 has a very small interior volume in comparison to its condenser size, even the stock condenser should do well with R134a as long as your shrouds/fans are in good working order.

Dan
'91 928GT S/C 475hp/460lb.ft

 

Lack of cooling on hot days, (Atlanta gets hot) reduced life of compressors due to higher systems pressures, are the main ones.

One of the biggest issues is that there is no high pressure cut offs in most R12 systems like there are in most factory 134a systems, on a hundred degree day you can see VERY high pressures with 134a on a converted system.

Lets face it, there really is zero reasons to convert a 928 to 134a as long as you can get R12, and many reasons not to.

 

5 speed GTS also have the smaller condensers.

 

Sorry, you are correct. The 5-speed GTS has the transmission fluid cooler there. So the aftermarket condenser I am using will only work with '87 - '91 5-speed 928s as a drop-in replacement.

Dan
'91 928GT S/C 475hp/460lb.ft

 

So, on a 100 F day, with your shark converted to R134a, what was the
high side pressure at idle?

 

Depends on the airflow past the condenser and IF it had the correct charge in it, but I have hooked up to cars that others have converted and seen around 400 on the high side.

Mine is not converted to 134.

 

Oh. Ok.
Just a suggestion: with R134a on 100F ambient day, in your shark, I'd try to shoot for no higher than 276 (mean) psi on the high side, at idle.

 

Thanks, but I am going to stick with R12.