The more difficult but appreciably quieter route is to disassemble the compressor and suck the whole system of oil. Then use a "proper" R-134 oil and recharge. I've done this twice now, and it was very noticable the change in compressor noise. But it's a tedious job.
The trucks all would cool poorly if the system was low. Be it R-134, or the older R12. Being ever high tech, I would throw a can in, and be satisfied. The wifes car was/is low enough that I might throw a second can into it.
None of them cool as well at idle as they running down the road. The compressor is spinning faster, and it cools better. But set up correctly, all of them were quite cool sitting in traffic, 100+ degrees, baking in the sun.
Is yours idling up the engine enough at idle to compensate for the load? And does yours have that control unit that frequently cuts the compressor out at idle? The earlier Toyota trucks were infamous for having no cooling at idle because of this.
Good points, all, Fox.
does putting a vacuum on the system get all the oil out? or does it leave some in? if so, where is it? in the compressor? the drier?
if I go the long route, I want to make sure I'm putting in the right amount of oil.
also, your note about compressor noise -- that's one of the things I noticed when I did this last using the combo cans of oil & refrigerant -- compressor noise. rattley.
I have a Weber carb, so no dashpot or idle up mechanism except for my foot, which, at stops, I hold it at 1000rpm.
just got a call from the shop. my Mazda's ready. I'll come back and post the results for comparison -- I know it's not an apples to apples, but it's an R-12 to 134 conversion, so if anyone's interested in a "professional" result...
