themoneypit Posted March 9, 2012 Share Posted March 9, 2012 my 88xt6 loves to run hot when using the a/c thats been converted to r134a. id like to go back to r12. i have recently scored a few cans of r12, and an oil charge. my question is this. i have the guages and evacuation pump to completely evacuate the system. is this good enough, or do i need to somehow flush out the system? let me know, thanks. i had the radiator professionally flushed and didnt help. when it starts to run hot, if i shut off the a/c the temp comes back to normal. thats what has me convinced the r134 is causing it to run hot. Link to comment Share on other sites More sharing options...
desertsubaru Posted March 9, 2012 Share Posted March 9, 2012 Does the secondary fan come on when it starts getting hot? Link to comment Share on other sites More sharing options...
robm Posted March 9, 2012 Share Posted March 9, 2012 Flushing rads has a poor reputation on this board. I would check the rad for cool spots, indicating poor flow through it. Lots of good info here, that might answer your question: http://www.aa1car.com/library/retrofit.htm Link to comment Share on other sites More sharing options...
themoneypit Posted March 10, 2012 Author Share Posted March 10, 2012 (edited) Flushing rads has a poor reputation on this board. I would check the rad for cool spots, indicating poor flow through it. Lots of good info here, that might answer your question: http://www.aa1car.com/library/retrofit.htm maybe my radiator still is the trouble? i just found a NOS replacement, so i guess ill try that first b4 reversing the a/c back. for the xt6 the radiators are dealer only, and discontinued, so i got lucky finding this one. i searched everywhere last year for one and couldnt find one. so i had no choice but to have the stock one flushed.... Edited March 10, 2012 by themoneypit Link to comment Share on other sites More sharing options...
pressingonward Posted March 10, 2012 Share Posted March 10, 2012 Switching refrigerants will NOT solve your problem. Like someone else suggested, make sure that your electric fan kicks on when the AC cycles on. A plugged radiator could definitely be the problem. A thermostat that only opens halfway could do it too. I've also seen water pumps that the impeller is corroded away to nothing that cause vehicles to run hot under heavy loads (running the AC constitutes a heavy load) Link to comment Share on other sites More sharing options...
themoneypit Posted March 10, 2012 Author Share Posted March 10, 2012 Switching refrigerants will NOT solve your problem. Like someone else suggested, make sure that your electric fan kicks on when the AC cycles on. A plugged radiator could definitely be the problem. A thermostat that only opens halfway could do it too. I've also seen water pumps that the impeller is corroded away to nothing that cause vehicles to run hot under heavy loads (running the AC constitutes a heavy load) i beg to differ. r134 runs WAY hotter than r12 does. thats why you can only charge it to @85% capacity in an r12 system. yes, the rad may be PART of the problem, but the 134 is def a major contributor. ive had a dozen xt6's, ALL that have been converted run hot with the a/c on, the ones with r12 dont. if it was a theromostat, then it would do it regardless of the a/c being on or not. timing belts and water pump were done within the last 30k miles, so i highly doubt thats the issue also. at this point, im going to just evacuate the system, install a different dryer that has a clear window, add oil, and charge it up. Link to comment Share on other sites More sharing options...
pressingonward Posted March 10, 2012 Share Posted March 10, 2012 The charge for R134A is less because it is a different refrigerant with different operating characteristics. How are you charging your cars? If you are over-charging them the high-side pressure will go up along with the temperature, which could cause the car to run maybe 10 degrees hotter. Define what you mean by "running hot" anyways. Are we talking at idle, cruising down the road, heavy throttle? How hot does it get? A thermostat that will not open fully can cause the car to overheat under heavy load because it restricts coolant flow. It might flow enough to be ok under normal conditions, but not under heavy load. Regardless I doubt that is your problem, it's a pretty rare thing to happen. Link to comment Share on other sites More sharing options...
pressingonward Posted March 10, 2012 Share Posted March 10, 2012 And just a note on going back to R12: If your R134A conversion used Ester oil you'll be fine. If it used PAG oil, it may or may not be compatible with the R12 (depends on the type of PAG oil). You can get cans of A/C flush from NAPA, but flushing isn't very effective for certain parts of the A/C system, especially the condenser Link to comment Share on other sites More sharing options...
themoneypit Posted March 11, 2012 Author Share Posted March 11, 2012 And just a note on going back to R12: If your R134A conversion used Ester oil you'll be fine. If it used PAG oil, it may or may not be compatible with the R12 (depends on the type of PAG oil). You can get cans of A/C flush from NAPA, but flushing isn't very effective for certain parts of the A/C system, especially the condenser awesome, thats the info i was looking for... it was converted using ester oil (so thats good ) ive swapped t-stats, used lower 180 degree ones, oe temp ones, oem ones, doesnt matter... as far as "running hot" it would get almost to the H marks on the guage. it never boiled over, but was def close to it. i believe the high side like u stated is getting too hot, causing the rest of the cooling system to get hot. thats great then, i will evac the system, and recharge it with r12 then. should i use ester oil again? or should i use the r12 oil charge can i have? i will look into the cans of a/c flush at N.A.P.A. (never any parts available lol) Link to comment Share on other sites More sharing options...
pressingonward Posted March 11, 2012 Share Posted March 11, 2012 Use the R12 oil. Ester Oil is not as good of a lubricant. It is important to add the correct amount of oil. Keep in mind that some of the oil is sucked out when you evacuate the car, but a lot of it is still in the system. If you flush the system you need to take the hoses off and flush each component individually. My A/C service book recommends blowing shop air (non-lubricated obviously) through the component for 30 minutes after flushing to blow out/evaporate all of the flush. Here are my A/C book's recommendations for oil amount: 1. Add the amount that the A/C machine sucks out 2. If the car has a receiver/dryer that you are replacing, add 1 oz. If it has an accumulator that you are replacing, add 2-3 oz. An accumulator is on the low pressure side of orifice tube systems (between evaporator and compressor). A receiver/dryer is on expansion valve systems and is located on the high side of the system. I'm not sure which system Subarus use. 3. Add 1 oz for a replaced or flushed condenser 4. add 2-3 oz for replaced or flushed evaporator 5. If you are draining or replacing a compressor (DO NOT flush the compressor), take it off the car and pour the oil out into a measuring cup while turning the compressor over by hand to drain it fully. Pour the same amount plus one additional oz into the new compressor. If the compressor has a lot of oil in it (say 7 oz and the system oil spec is 8 or 9 oz) the system was probably over-oiled. Guestimate how much oil is in the rest of the system and add the remainder to the compressor (at least a couple oz for startup lubrication) Make sure you evacuate the system and hold it in vacuum for 20-30 minutes to boil off any moisture in the system. Link to comment Share on other sites More sharing options...
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