When I purchased my MCI 7 1978 the PO told me the road AC worked but had gotten low on freon. Being R12 it took me awhile to find 2 bottles of this liquid gold, but now I'm ready to attemp to revive the system. My question is do I charge the system with some and check for leaks with the sniffer or pull a vacuum and replace as I said PO said it was working just got
Low over the few years he had the bus and he was in northern cal and had little use for it. If charging what pressures show I be looking for manual is all over the place on values.thanks
Pull a vacuum down to 30 and the charge will be all over the map the altitude and outside temperature play a big part in the process. Sometimes I use nitrogen to find the leaks the R12 is like gold and the bus systems have lots of places to leak it may take you awhile to find
Buses are notorious for dirty condensers clean that first and check the motor and fan to get a good charge
good luck
I might have been pricey at one time but since there is almost no call for it anymore R-12 is pretty cheap.
http://www.ebay.com/itm/DUPONT-R12-FREON-50-POUND-CAN-/161344507553?pt=Motors_Car_Truck_Parts_Accessories&hash=item2590e1cea1&vxp=mtr (http://www.ebay.com/itm/DUPONT-R12-FREON-50-POUND-CAN-/161344507553?pt=Motors_Car_Truck_Parts_Accessories&hash=item2590e1cea1&vxp=mtr)
If the system has pressure I don't evacuate, especially if it has 30psi or more on a warm day.
If you have to evacuate that is automatically a leak test, won't show the location of a leak though. Dye is good for that.
Never had any luck with sniffers.
I use Big Blu good stuff for leak detection
FYI,
It might be cheaper to have it converted to 134A rather then purchase R-12.
Many still don't know that R-409A is a direct replacement for R-12 (has been for 15 years) and a 1/16th the price....
Best of luck
Nick-