Air conditioner recharge?

Just want to include an example of what one might see when charging with actual two-gauge manifold. Last year, I did it with a minivan. Initial pressure readings were 180 high and 35-40 low. The low-side figure was actually OK for that vehicle (dual evaporators) but since high side was on the low end of the range, I thought cooling can be improved. When adding refrigerant, the pressures changed to 200 and 25-30. This should be typical at least when a system is slightly undercharged: the suction pressure in fact goes down.

As to Interdynamics, I would only buy pure refrigerant under their brand (but then you can buy DuPont). They don't write on their cans exactly what's put in. For instance, in kits with oil, the oil is esther, while factory fill in the system is PAG. The only way to find was from MSDS on their site.