A/C upgrades (R134) - Operation Chill
- Thread starter Satan
- Start date
Satan;1295023 said:
I assume everyone does the wrong thing on this forum unless they indicate otherwise.
After searching this thread over I see my lapse in judgment in this case.
Although this post was nowhere near the end of the thread.
My point was a system charged without being evacuated can't possibly attain vent temps of 42 degrees...
^^I pulled vacuum for about 50 minutes and then let it hold for another hour, before adding the freon. I screwed up tho and forgot to close the low-side valve when switching to the 2nd can of freon.
I've heard that once it runs through the system a bit, it's supposed to get better (maybe colder)? Did not see anything substantiating the statement, so don't believe it to be true. At the next oppty I have to refill, I will certainly pay attention to closing the valves when I am supposed to.
I'll post the product specifics in a bit, so that others can order and installl successfully. I am also doing a last-ditch effort towards volume pricing.
I've heard that once it runs through the system a bit, it's supposed to get better (maybe colder)? Did not see anything substantiating the statement, so don't believe it to be true. At the next oppty I have to refill, I will certainly pay attention to closing the valves when I am supposed to.
I'll post the product specifics in a bit, so that others can order and installl successfully. I am also doing a last-ditch effort towards volume pricing.
How did you come up with that charge amount? What blower speed was the 42 at? What vent? Recirc or fresh? High and low side pressures after stabilization? Coolant valve on there and working?
At 75 ambient (what RH?) you're not asking much of the system. I'm not saying it won't work when warmer but there are ways to tweak it if it doesn't.
At 75 ambient (what RH?) you're not asking much of the system. I'm not saying it won't work when warmer but there are ways to tweak it if it doesn't.
rmjsupra;1313081 said:
Nope, used the Aristo 2JZ compressor with the 7M top plate and lines. The P/S bracket had to be notched slightly to clear the lines, but it worked out very well.
jetjock;1313347 said:
How can you know that it is heatsoak that is affecting the H/L pressures? and not an overfill issue?
Should the pressures sit stable at idle? I have a huge floor fan i can stick in front of it but that seems like cheating to get accurate readings. 95 degree ambient measured at 2" in front of condenser. High side will rise (225psi) until the ac fans kick on and drop it down some (idle). Low side sits around 28-30psi.
r12, vent temps at 42 with recirc on after 10-15 minutes of city driving, measured at medium fan speed at the left center vent.
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Those numbers look OK. Since R12's temp/pressure curve is fairly flat a suction pressure of 30 psi means the stuff is close to 30 F which is what it should be with a working expansion valve. Keep in mind the evap isn't allowed to go below freezing or it'll ice up. Add the typical 10 degree or so drop across the evap (after all shouldering a heat load is it's job) and you get around 40-45. I'd say your system is working well.
Pressures should be stable at a fast idle/2000 rpm which is where systems are usually checked. The fan is a good thing...techs will use one to stabilize a system for performance tests. High side will change and is less important than low side as long as the system is working. A general rule of thumb for R12 is high side should be about 2.2 times ambient measured near the condenser face.
There are better ways to determine optimum charge than weight especially in a converted system. Superheat for example. There's a point where picking things apart isn't worth it though. Remember, in spite of the technical minutiae one can get into about this stuff, all that matters is "cold"
Pressures should be stable at a fast idle/2000 rpm which is where systems are usually checked. The fan is a good thing...techs will use one to stabilize a system for performance tests. High side will change and is less important than low side as long as the system is working. A general rule of thumb for R12 is high side should be about 2.2 times ambient measured near the condenser face.
There are better ways to determine optimum charge than weight especially in a converted system. Superheat for example. There's a point where picking things apart isn't worth it though. Remember, in spite of the technical minutiae one can get into about this stuff, all that matters is "cold"
When charging, I just went by guage readings and low was sitting at about 28psi and high was at ~230psi... I kept filling 'til I got to as close to "normal" settings as described in the TRSM, for an R12 system.
When I added the next new cans, I purged the line, so am sure that I did not entirely use the 26 or so ounces of freon in the system. That's just how many ounces I used in the process (about 26oz). My target/intent was near 24oz, since that's what the Toyota retrofit instructions called for (650 grams of freon).
EDIT lubricant info:
I used PAG 46. I had drained the compressor before and did it again (turning the insides about 20 times, to allow more oil to drain).
I am using an Aristo A/C compressor, which already used R134, so I did not have much incompatible oil. I used the PAG 46 instead of Ester, in case there is some leftover old lubricant in the evaporator or other areas of the system.
As tested:
R134, vent temps at 41.8 with recirc on after 10-15 minutes of city/hwy driving, measured at high fan speed at the left center vent.
In addition, I am missing the lower A/C pipe that takes air to the left-most vent on the driver's side. So, I was losing a large volume of air which was flowing directly to my feet and it felt very cold too :biglaugh:
I should have another vent-pipe thing arriving soon and will retest when I have it on, to see if there's any difference.
Overall, I am VERY pleased with the results. I think that those who are seeing good temps from their R134 converted stock/serpentine condensors may be because they are newer or in extremely good shape. Whereas a beat-up, opened-up system may have taken it's toll on the efficiency of the condensor and therefore poor results when a R134conversion is done. Unfortunately, the 2 times I've had mine done (2 diff. MKIIIs), the results were poor and unpleasing.
So, before you go R134, either KNOW that your condensor is perfect, or replace with a parallel-flow condensor for "guaranteed" results (cold-@$$ air).
When I added the next new cans, I purged the line, so am sure that I did not entirely use the 26 or so ounces of freon in the system. That's just how many ounces I used in the process (about 26oz). My target/intent was near 24oz, since that's what the Toyota retrofit instructions called for (650 grams of freon).
EDIT lubricant info:
I used PAG 46. I had drained the compressor before and did it again (turning the insides about 20 times, to allow more oil to drain).
I am using an Aristo A/C compressor, which already used R134, so I did not have much incompatible oil. I used the PAG 46 instead of Ester, in case there is some leftover old lubricant in the evaporator or other areas of the system.
As tested:
R134, vent temps at 41.8 with recirc on after 10-15 minutes of city/hwy driving, measured at high fan speed at the left center vent.
In addition, I am missing the lower A/C pipe that takes air to the left-most vent on the driver's side. So, I was losing a large volume of air which was flowing directly to my feet and it felt very cold too :biglaugh:
I should have another vent-pipe thing arriving soon and will retest when I have it on, to see if there's any difference.
Overall, I am VERY pleased with the results. I think that those who are seeing good temps from their R134 converted stock/serpentine condensors may be because they are newer or in extremely good shape. Whereas a beat-up, opened-up system may have taken it's toll on the efficiency of the condensor and therefore poor results when a R134conversion is done. Unfortunately, the 2 times I've had mine done (2 diff. MKIIIs), the results were poor and unpleasing.
So, before you go R134, either KNOW that your condensor is perfect, or replace with a parallel-flow condensor for "guaranteed" results (cold-@$$ air).
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jetjock;1313436 said:Those numbers look OK. Since R12's temp/pressure curve is fairly flat a suction pressure of 30 psi means the stuff is close to 30 F which is what it should be with a working expansion valve. Keep in mind the evap isn't allowed to go below freezing or it'll ice up. Add the typical 10 degree or so drop across the evap (after all shouldering a heat load is it's job) and you get around 40-45. I'd say your system is working well.
Pressures should be stable at a fast idle/2000 rpm which is where systems are usually checked. The fan is a good thing...techs will use one to stabilize a system for performance tests. High side will change and is less important than low side as long as the system is working. A general rule of thumb for R12 is high side should be about 2.2 times ambient measured near the condenser face.
There are better ways to determine optimum charge than weight especially in a converted system. Superheat for example. There's a point where picking things apart isn't worth it though. Remember, in spite of the technical minutiae one can get into about this stuff, all that matters is "cold"
cool, thank you jj!
Welcome Grim. Note what I said is for a TXV system. CCOT (orifice tube) systems will be different. And it's funny how the AC questions pop up every year about this time
Satan: Once the car cools down try it on low fan. I'll bet the longer residence time puts it into the 30s...
Satan: Once the car cools down try it on low fan. I'll bet the longer residence time puts it into the 30s...
Of course a lower fan setting is going to give you lower temps... all you are doing is extracting less hot air from the cab. Thats not a real test though. According to all the reading i have done you should have proper vent temps at high fan speed, upper vents only, recirculate, idle, and measure the temp at the center vents. Hell with my serpentine condenser idling on a hot day i could probably achieve close to 35 degree vent temps on low fan setting.
I never said it was a good test, just making a point. And maybe my memory is slipping but I seem to recall your system doesn't work well. Considering your frequent proffering of advice on the subject I find that strange...
I never said any of it was good advice, always just making a point.. lol.. jk. It seems almost every time i comment on something you said you take it personally, i don't know why, but im not trying to say that what you said is wrong, inaccurate, or anything like that so please don't take it as such.
Something I did when i was testing out my AC, is i took a temperature thermocouple and stuck the end of it through the foam insulation directly after the evaporator core and used that as a temperature readout. That way I could see exactly what the evaporator temps were doing and anything affecting temp downstream such as the heater core or vent doors would not show up. Just an idea if you think you could have a problem elsewhere.
Something I did when i was testing out my AC, is i took a temperature thermocouple and stuck the end of it through the foam insulation directly after the evaporator core and used that as a temperature readout. That way I could see exactly what the evaporator temps were doing and anything affecting temp downstream such as the heater core or vent doors would not show up. Just an idea if you think you could have a problem elsewhere.
Finally got some pricing, but still not as good as I'd hoped.
They did offer free freight (to 1 location) if 30 units are ordered. Cost is $125 each condensor, which would tie up almost $4K and a bit of my time for shipping. I could have it shipped to someone else with more time. Still a decent price, considering not having to change lines or other fabrication to make 'em fit.
I am still getting more details and trying to bring that price down a bit. I will also need to get with the admins of the different forums to make sure I get approvals and stay within whatever the guidelines are out there.
They did offer free freight (to 1 location) if 30 units are ordered. Cost is $125 each condensor, which would tie up almost $4K and a bit of my time for shipping. I could have it shipped to someone else with more time. Still a decent price, considering not having to change lines or other fabrication to make 'em fit.
I am still getting more details and trying to bring that price down a bit. I will also need to get with the admins of the different forums to make sure I get approvals and stay within whatever the guidelines are out there.
Satan
what type of vacuum pump did you use?
41.9, that is nice and chilly but the real test is during the hot weather. If it cools that good during, say a 90+ degree day. Then you are GOLDEN!
what type of vacuum pump did you use?
41.9, that is nice and chilly but the real test is during the hot weather. If it cools that good during, say a 90+ degree day. Then you are GOLDEN!
My A/C is completly rebuilt and converted.. except the previous owner bought a used condenser and it leaked, Wouldnt mind replacing that and getting it recharged. Anyone know where to get one for cheap? I dont want to throw a wack of money at it only to find out it leaks somewhere else.