Howdy Gents, I just had the A/C in my 400i serviced. The shop manual calls for 3.3 pounds of R12 for the dual air set up. With that much in the system the high pressure side exceeded 250 psi on the gauge and cut the compressor off and on. It cycled like this about every 10 seconds. On a hunch we cut the R12 to 2.7 pounds and the system works beautifully with the gauge steady at 250 psi. The exhaust note is also rock steady. Does anyone have a better fix on the maximum R12 in the system? Greg
With the high side at 250 what does the low side read? If it is lower than normal the oriface tube/s could be partially plugged. On the other hand if the system is working why change anything?
I regret that I didn't pay a lot of attention to the low side psi. I think it was above 70 on the evacuation cycle and the last time I looked it was above 50 and climbing on the recharge cycle. It may have been 90 psi while the head pressure was 250 but I am guessing about that number. The manual talks about restrictions but we tried the lower head pressure as the path of least resistance and it worked. The alternative would have been to track down new parts. I do remember the technician saying the final result was within the shop manual's BAR recommendations. Greg
Normally when the compressor goes into an on/off mode every 10 seconds or so the coolant level is to low. BTW, is R12 still available in the US? Or did he use the R413a or R401a?
I had two cars done on the same day with the same machine. The first was 10% low and it cycled. The Ferrari cycled at the recommended charge but calmed down, and fell into the recommended bar numbers at 15% low. This seemed odd and so I asked my question. R12 can be had, installed only, from certified installers here in Missouri for a mere $70.00 a pound.
