Factory AC Will Freeze You Out
Since I have a magnum swap, I was just going to use everything from the donor Ram except the evaporator, and connect it all to the factory Dart evaporator using some custom hoses.
Any reason I can't do this?
NONE. You will have to "adjust the charge" because two things.........Going from R12 to 134 charge weight is different, but here you are building a one-off custom system. You need to learn to charge by superheat and subcooling, and to "anticipate" (and or recheck readings) at different conditions of operations
For example........If you charge it up (stationary of course) on a cool day, with plenty of "blower" into the radiator, and if the interior is fairly warm, then on a warmer day the higher head pressure may push more refrigerant back under some conditions and cause a danger of flooding to the compressor.
This can be a real issue, and in the case of bone stock systems, the charts in the manuals have all this (allegedly) thought out for you.
Worst conditions for low side end to cause flooding back is when interior is COOL Depending on the system, the high side contribution can be worse either in cooler conditions or warmer conditions. So you need to check for both Superheat is your friend.
You do this by taking the temperature of the low side line coming back to the compressor. You need to wrap it with something to insulate the temp sensor and avoid erroneous readings from engine heat.
Now you look at the pressure of the low side, and go to a chart, convert that across to temperature. The difference in your two temp figures is the superheat. I would not want to see less than 10-12F superheat under worst conditions.
As superheat drops towards zero, you get more and more liquid droplets going back to the compressor
Subcooling in a case like this is secondary, but gives you an idea of what the condenser is doing. It is similar to superheat. You take the temp of the liquid line leaving the condenser, and read the high side pressure, and convert that to temperature. Again, the difference is subcooling. Generally, the higher the reading, the more efficient the condenser is working. Low readings can mean dirty/ too small condenser, undercharge, or that system is trying to work way above it's capacity (overloaded, hot day)
