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Got the AC system in and now driving it. The air is cool, not bitter cold with 24oz of R134 and 5oz oil, but it's pretty good for now. I'll let it cruise for a bit, then work on fixing the climate control computer and figuring out why the vacuum servos aren't working for the recirc air and heat line (manually bypassed for now)
Got the AC system in and now driving it. The air is cool, not bitter cold with 24oz of R134 and 5oz oil, but it's pretty good for now. I'll let it cruise for a bit, then work on fixing the climate control computer and figuring out why the vacuum servos aren't working for the recirc air and heat line (manually bypassed for now)
What is the temp at the center vent? I keep a $10 ac temp probe in my vents all the time. My 944 has never had the air working.
In 95°F Texas heat, 50% humidity, I was getting 41°F from my 08 Civic at highway speed, just under 50° at stoplights in the heat of the day.
In my 00 Silverado, it has a slow leak and is a little low on R134a, and it was blowing a steady 60°F in 95° Texas heat, both at highway speed and at idle.
I am learning more about how to work on AC. When I get the 944 going, I am fixing the AC. Texas is just too damn hot.
What is the temp at the center vent? I keep a $10 ac temp probe in my vents all the time. My 944 has never had the air working.
I was curious how my AC systems worked, so I grabbed a digital meat thermometer, popped it into the center vent and tried 3 cars:
Test conditions:
85 degrees, 80% humidity typical crummy Maryland day.
Fans at full speed (4)
Readings read with AC off, AC on at 2k RPM, AC on at 60mph on highway, AC on at idle at end of drive
Observations:
The Insight is pretty much the "reference" car. Small compressor but very big condenser (2x size of 944S) and built for R134a. Works great, slow as dirt, 48F is probably what I am looking for.
944S: Not bad, blows cooler at highway speeds, at idle the compressor is probably spinning a bit too slow.
928S: Bigger condenser if I recall but once again not much airflow at idle. I think the front super fan isn't that great, wish there was something better. Maybe I can build a 12v-18v boost converter and run the fan at higher RPMs.
So.... Interesting. Not sure if adding R134 will make a difference in either case, they are both "cool enough for me" and comfortable when temps are in the 90's and I'm on a long distance drive.
Note that results will vary based on outside temp, humidity, pretty much everything.
In 95°F Texas heat, 50% humidity, I was getting 41°F from my 08 Civic at highway speed, just under 50° at stoplights in the heat of the day.
In my 00 Silverado, it has a slow leak and is a little low on R134a, and it was blowing a steady 60°F in 95° Texas heat, both at highway speed and at idle.
I am learning more about how to work on AC. When I get the 944 going, I am fixing the AC. Texas is just too damn hot.[/QUOTE]
I was curious how my AC systems worked, so I grabbed a digital meat thermometer, popped it into the center vent and tried 3 cars:
Test conditions:
85 degrees, 80% humidity typical crummy Maryland day.
Fans at full speed (4)
Readings read with AC off, AC on at 2k RPM, AC on at 60mph on highway, AC on at idle at end of drive
Observations:
The Insight is pretty much the "reference" car. Small compressor but very big condenser (2x size of 944S) and built for R134a. Works great, slow as dirt, 48F is probably what I am looking for.
944S: Not bad, blows cooler at highway speeds, at idle the compressor is probably spinning a bit too slow.
928S: Bigger condenser if I recall but once again not much airflow at idle. I think the front super fan isn't that great, wish there was something better. Maybe I can build a 12v-18v boost converter and run the fan at higher RPMs.
So.... Interesting. Not sure if adding R134 will make a difference in either case, they are both "cool enough for me" and comfortable when temps are in the 90's and I'm on a long distance drive.
If you are comfortable, then all is good. Last few summers in Texas we have had 103°-105° F, and that is the temp, not the heat index. So down here, my AC needs to work well or we burn up in July and August. The sweet spot on my AC thermometer is a green highlighted section from about 38°–42° F. The heat load here is tremendous.
If you are comfortable, then all is good. Last few summers in Texas we have had 103°-105° F, and that is the temp, not the heat index. So down here, my AC needs to work well or we burn up in July and August. The sweet spot on my AC thermometer is a green highlighted section from about 38°–42° F. The heat load here is tremendous.
Interesting. If I might ask what are your high/low pressures, and how much R134 do you have in the system?
I always wonder if I have too little, too much, or if this is just the limits of a stock 944S/928 that is running a converted system with the original R12 expansion valve.
Interesting. If I might ask what are your high/low pressures, and how much R134 do you have in the system?
I always wonder if I have too little, too much, or if this is just the limits of a stock 944S/928 that is running a converted system with the original R12 expansion valve.
I have read from numerous sources that the tube and fin condensers that were stock for 80s Porsches, don't perform as well with R-134a as they did with R-12. People who have changed to a parallel flow condenser in 944/928 have gotten better heat transfer from the condenser and therefore colder temps at the vent. You asked what my readings are. I have not fixed my 944 AC, and it hasn't worked since before I bought it. So here are my recent readings of my truck and car:
2008 Honda Civic 1.8L (4 door) EX-L (I don't know how much R-134a is in it, as I had the service station top it off about a year ago.) And the crazy thing with that... drumroll, the blend door was sticking partially open. I figured that out by turning it all the way to hot, then back to cold.
Anyway, Civic readings from 7/4/23:
And here is my 2000 Silverado, which definitely has a leak in the AC system. Service station added R134a about three weeks ago, it was low on refrigerant, they added one 12 oz can. The compressor was short-cycling and not staying on. They added R134a at the beginning of the (2022) summer and my truck was cold AC all last summer. So some R-134a leaked out since the end of last summer. The system wasn't completely empty, just low. Silverado readings on 6/18/23 – Before they added refrigerant. (Ac wasn't working)
2000 Silverado Readings 6/30/23 — After Grimes added R-134a:
I am cutting my teeth learning to work on these other truck's AC systems, so that maybe before this summer is over, I can change my 944 from R-12 to R-134. I plan on switching to a parallel flow condenser, repairing any leaks, and starting with a new compressor, probably from Griffith's as they have good reviews from people in the community. FYI, I am not a mechanic by trade, but I want to learn to work on auto AC, partly to save money, but more so because I like working on my own stuff, and AC work is my next Everest to conquer.
I researched how to convert my a/c system to 134a and wrote a post in this thread years ago. I remembered getting temps in the 40s F from the dash vents, measured with a meat thermometer.
I researched how to convert my a/c system to 134a and wrote a post in this thread years ago. I remembered getting temps in the 40s F from the dash vents, measured with a meat thermometer.
Drove the 924S I Need to get the center console back in. Trying to get all things electric working on this car which included rear window wiper, mirrors and possibly sunroof. Also drove 944S yesterday have pretty good drive but need to figure out slow start after sitting 20 min, thinking bad pressure regulator or leaking injectors. Always something but enjoying the ride. The journey is it's own reward. With the 924S every time I get in that car, even if it's a sleepy need more coffee morning by the time I drive it a few miles I swear I'm the incarnation of Steve McQueen driving around LeMans.... it just makes me want to drive faster and faster. I love it.
Working in the preventative maintenance mode these days. I installed the only944 shifter with thrust bearings. There was no measurable wear on the transmission linkage or the shifter cross rod. Plating was worn a little thin, but the white lithium grease was still present and soft. Should be no wear going forward.
07-07-2023, 02:20 PM
