I would go with DuraCool if I were to try a retail option. Right now, I am trying to figure out if I can get some off the shelf, cheap alternatives to work. Like I said, I have plenty of R12 if I want it. This is more of an exploratory project.

I added 16OZ of MSR IsoPro stove fuel. I hear it is 80% butane and 20% propane. What I put in is probably close to if not over an efficient charge to fill the evap. The problem is that the ratio is too far in favor of Butane. I did get nominal cooling with just the MSR but not near what I should be getting. I added several ounces of propane and started to get slightly cooler temps but the low and high side pressures started to climb. I need to bleed the system down to a reasonable ratio between high and low pressures, then bump it with some more propane and see if I hit a sweet spot. The ideal ratio is somewhere between 40-70% butane but it really depends on the OAT.

 

Need a restriction in your suction line to keep your low pressure up and highressure lower I used vicegrips to pinch the hose off lol but is very cold now. 32 at the vents, I have my thermometer set at 35,36 in a glass of ice water, hope this helps

 

Your low side should be 60-70 psi. Use the smallest oriface possible. The variable one doesnt work as well with propane. I had to figure out the hard way. What you need is restriction in the suction line to raise your low side pressure and lower your high side pressure. TRUST ME

 

Does your truck have valves behind the compressor? You can close off the suction valve 3/4 or so and that will do the trick

 

I'll get back to this thread in the summer. Right now it is too cold to get readings from the A/C.