69sroadster Posted June 23, 2013 Share Posted June 23, 2013 I did a quick search in our forum but didn't notice any related data. Anyone do a R-134 conversion on their ZX and how does it perform on a hot day? I just did a quick test of mine and it was showing about 69 F on a 92 F day here in Arkansas. Mine is running the SR20 compressor with an unknown amount of life on it and the original condensor/evaporator. I did switch out to a new receiver/drier though. I am tempted to evacuate the system, purge the lines and compressor, change the filter again and swap in a new condensor but it may just all be wasted efforts if I only get a few more degrees cooler. I almost forgot I did upgrade the fan motor and cage to the 300zx one. Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted June 24, 2013 Share Posted June 24, 2013 Did you flush the evaporator and condenser, replace the expansion valve with an r134a unit and replace the dryer? Charge the system with 2-4 oz of pag oil. Pull a good vacuum before charging for 15-30 minutes. Do you have some high and low side pressure readings with the ac on? Quote Link to comment Share on other sites More sharing options...
69sroadster Posted July 3, 2013 Author Share Posted July 3, 2013 Awesome questions. I did flush them as best I could with the lines in the car but disconnected using an air compressor and hose nozzle. I did not have an R-134 expansion valve, but if I can get one to replace the stock R-12 one then I would. Any ideas on that part? That's inside the airbox next to the evaporator right? I did have that entire assembly out at one point to replace the heater core and flushed what little there was on the evaporator off at the same time. I did replace the dryer and charged it with R-134 oil not the R-12 stuff. I pulled a good 24-26 lb vacuum for about an hour (it's been a while since I did this so I forget the exact value it got). After pulling vacuum I let it do a leak down (or up depending on how you look at it) check and it didn't move at all on the gauge after sitting for another hour. My pressure manifold is currently in storage during my house move, but I may be able to get some readings if I borrow my brothers set. Maybe that will give some other good/bad indicators, but off the top of my head and memory I seem to recall low was around 30-40 something and the high was 250-ish. It'd be better if I just check it again. Quote Link to comment Share on other sites More sharing options...
Chris83zxt Posted July 27, 2013 Share Posted July 27, 2013 69 is pretty meh. I recharged my factory system with R12 prior to a long road trip back in June. I also installed a ball valve in the heater hose that goes to the heater core (if you do this I recommend you install it on the return line so you don't have hot coolant recirculating through your motor continuously). With the valve open and coolant running through the heater core, I was getting 52 degrees out of the vents. With the valve closed, I got down to 34.6 out of the vents at one point on the trip. Due to a silly and expensive mistake on my part, my r12 all leaked out, so I have since recharged with enviro-safe 12a (ES-12a) which is a propane blend. With the valve open it will drop down to around 54, closed 66 or so. I've never retrofit R-134a into a datsun, but 69 degrees sounds almost like a waste of time, especially if your car has t-tops. PS - When charging an auto A/C system have the blower on full blast, the windows down, and the car idling at 2,000 rpm. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 28, 2013 Share Posted July 28, 2013 As the previous post points out, HOW you test is very important as it greatly affects the outcome. The FSM has detailed tests to check the performance, based on ambient temperature. I'm recalling "max cool, recirc, windows open" and a minimum temperature of 35F Center register somewhere around 69 or 75F ambient going up linearly from there. So 95 would be around 55F...but CHECK THE FSM! Don't go by my recollection! That said, generally it's said R134 is 10% higher. It didn't seem to matter n my aftermarket setup it returned the same 35F as R12 did under the same conditions. Maybe the compressor made up for the deficit by running 10% more, I don't know...it seemed the same to me. I recently recharged my GM Dually with that "Freeze 12" stuff off E-Bay, and like the cans said the pressures were off 10%, but thermally it performed exactly as the R12 did previously. Yeah, it took the season for it to leak out...but at least I checked it and it worked. Having AC in a Dually when you're loading parts in 110F heat is nice! LOL Quote Link to comment Share on other sites More sharing options...
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