I didn't go off pressure. I went off of a lot of research and performance. You can have the pressure as high as you want and it won't make a difference. Our systems have a high pressure burst disk if you got that high but propane at 30psi or 300 is still the same
Basing this off of 2 things:
1) I did these conversions back in the 90s, a lot of us shade-trees learned the hard way with it.
2) Apparently you didn't put in enough research, what's the boiling point of the isobutane at sea level? And at 3 bar? How about your blend?
I'm going to give a quick synopsis of the proper way to do this, and it will explain why you're very wrong, and did this improperly.
It will also show you how to fix this.
Steps:
1) Fix your system, draw vacuum, make sure it will hold a vacuum, add oil and keep system under vacuum.
2) Take an EMPTY 1lb propane canister, draw vacuum in canister.
3) Add isobutane to empty propane canister that is under vacuum.
*
4) Top off propane canister with pure propane from 1-lb canister.
*
5) Add propane/isobutane mix to system.
6) Add pure propane to top off system, bringing low side pressure to 30-35 PSI while running.
*Mixing the isobutane and propane in this fashion allows them to mix at low pressure. The isobutane has much HIGHER boiling point than the propane, if you add the isobutane to the propane, it will not mix, it will actually remain in it's liquid form in your system since the boiling point of isobutane is over 70°F at 30psi. The boiling point of a 70/30 propane/isobutane blend at 30psi is actually 0°C, which is 32°F.
The fact that your system was putting out such low temps should have been a severe warning if you were to heed it, you thought it was a good thing.
Oh, and any chemistry student in junior high would call that line I put in red either stupid or ignorant. Pressure raises boiling point, why do you think your cooling system is pressurized?
Draw vacuum, remix the right way, set pressures PROPERLY, and see how it performs.+
EDIT: The reason to use pure propane from a 1lb bottle, is the bulk propane in a 20lb is wet and impure. You don't want water in your system do you?