I have a 1990 Camry V6 LE with a slow leak in the A/C. The system ran completely empty over last winter, and is now not cooling. I purchased a RedTek refrigerant refill kit, but I've been told by family members who have recharged the coolant on other vehicles (notably a Jeep Cherokee) that a dual pressure switch may prevent the compressor from running with the coolant empty, and thus the system may not draw in the new coolant. Does anyone have experience recharging a Camry of this vintage from low-to-no pressure? Do I need to disable the dual pressure sensor? (It's noted in the schematic in the back of my Haynes manual, but not pointed out in any of the teardown photos -- where is it?)

 

The 1990 uses R12 Freon which was phased out. The Freon available at stores is R134a.

RedTek has a R12a product which is claimed to be compatible with R12 and supposed to have much better environmental specs then R134a. Have never used the product thus don't know.

If the system is loosing pressure over the winter this is a pretty good leak thus recommend a shop check out the leak. Otherwise the new recharge may last only a few days at best, this is not uncommon. Guessing the seal on the compressor drive shaft is leaking but who knows.

The pressure switch wiring is inline with the compressor magnetic clutch switch solenoid wiring. When the switch is open (low pressure), no power goes to the switch solenoid, the switch does not work and as such the magnetic clutch does not energize.

FYI, when you get the AC fixed suggest operating it at least 15 minutes each week summer and winter if possible. This will keep the seals and other components lubed reducing the chance of seal leaks and compressor problems.