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Where is your probe in the evaporator core? I initially had it close to the edge and it would freeze up causing warm temps. I would have to turn the thermostat to full warm, let the ice melt for about 10 minutes and then crank it back up. Once I moved the probe (inside the sheath) more to the middle, it worked perfectly. I think Charlie's instruction talks about pulling a vacuum for much longer than 10 minutes. You need to get in touch with him and he will walk you through it. If you have a vacuum pump, then no need for a shop other than to evaluate the charge to start over. I have continuously gotten low 30s for more than 13 years with my four condenser system in FL/AL summers. Good luck.
Pavegeno, I am extremely jealous of your results. I feel like the probe is in the correct place but no harm in trying to locate it further from the edge. Do you recall performing the thermostat Ice test before installing it? Charlie explains that you can hear the thermostat click on and off as it registers freezing and that is the point to mark and maintain as your "high" point to prevent the evaporator from freezing up. My click in the thermostat occurs just a few ticks past the ON position. I can't tell you if my evap is freezing or not but I do know when I first start the car and run the AC it performs well but if I stop at a store and shut it down for 5 minutes the AC struggles to get my lowest vent temps again. Not sure what to make of that.
I think your right about the vacuum being too short a duration, The shop I went to was not overly concerned about the instructions because they already know everything. I'm going to reach out to another shop with a good reputation and see if I can get them to cooperate a little better. I have spoken to Charlie many times but I think I have worn out my welcome a bit and I'm going to keep working through my issues as best I can.
Pavegeno, I am extremely jealous of your results. I feel like the probe is in the correct place but no harm in trying to locate it further from the edge. Do you recall performing the thermostat Ice test before installing it? Charlie explains that you can hear the thermostat click on and off as it registers freezing and that is the point to mark and maintain as your "high" point to prevent the evaporator from freezing up. My click in the thermostat occurs just a few ticks past the ON position. I can't tell you if my evap is freezing or not but I do know when I first start the car and run the AC it performs well but if I stop at a store and shut it down for 5 minutes the AC struggles to get my lowest vent temps again. Not sure what to make of that.
I think your right about the vacuum being too short a duration, The shop I went to was not overly concerned about the instructions because they already know everything. I'm going to reach out to another shop with a good reputation and see if I can get them to cooperate a little better. I have spoken to Charlie many times but I think I have worn out my welcome a bit and I'm going to keep working through my issues as best I can.
My dealer installed so not sure if they did the ice test. They did place the probe to close to the edge of the core. When I opened the evaporator case, I saw the probe right near the edge so moved it in where the directions said to place it.
Pavegeno, I am extremely jealous of your results. I feel like the probe is in the correct place but no harm in trying to locate it further from the edge. Do you recall performing the thermostat Ice test before installing it? Charlie explains that you can hear the thermostat click on and off as it registers freezing and that is the point to mark and maintain as your "high" point to prevent the evaporator from freezing up. My click in the thermostat occurs just a few ticks past the ON position. I can't tell you if my evap is freezing or not but I do know when I first start the car and run the AC it performs well but if I stop at a store and shut it down for 5 minutes the AC struggles to get my lowest vent temps again. Not sure what to make of that.
I think your right about the vacuum being too short a duration, The shop I went to was not overly concerned about the instructions because they already know everything. I'm going to reach out to another shop with a good reputation and see if I can get them to cooperate a little better. I have spoken to Charlie many times but I think I have worn out my welcome a bit and I'm going to keep working through my issues as best I can.
Contact the local PCA and Porsche dealers/mechanics. A good chance someone in your area has done the Griff's project and may be able to help. That's what I did.
Thank you, thank you, thank you for this write-up. I am seriously considering adding the extra condensers and replacing the existing evaporator & condenser and this write-up is a huge help. My 911 is black/black so it needs all the help it can get. When outside air is 85°F or below, the car is tolerable (vent temp 46°F after 10-15 minutes), but about that the system just can't keep up - the vent temps have to be mid-50s or lower to keep up with the heat load of a black/black car, even with the window tinting. To take the first steps, I just finished a compressor rebuild and installed new barrier hoses (all parts from Griffiths) in my '87 3.2 and I have a few potentially useful comments:
To anyone considering a different approach: Charlie Griffiths is a great guy to work with and he is ready, willing and able to give you as much tech support as you need. (Note: Charlie's facility is just a bit north of me, and small world that it is, he worked for the same company as I did many years ago.)
When evacuating & charging the system, be extremely careful that you don't get air into the system, especially if you are charging from 12 oz cans. My low-side pressure is fine, but the high-side pressure is much too high for the R134a charge, a obvious sign that either a condenser is blocked (which doesn't appear to be the case) or that I screwed up charging the system (much more likely).
Thank you, thank you, thank you for this write-up. I am seriously considering adding the extra condensers and replacing the existing evaporator & condenser and this write-up is a huge help. My 911 is black/black so it needs all the help it can get. When outside air is 85°F or below, the car is tolerable (vent temp 46°F after 10-15 minutes), but about that the system just can't keep up - the vent temps have to be mid-50s or lower to keep up with the heat load of a black/black car, even with the window tinting. To take the first steps, I just finished a compressor rebuild and installed new barrier hoses (all parts from Griffiths) in my '87 3.2 and I have a few potentially useful comments:
To anyone considering a different approach: Charlie Griffiths is a great guy to work with and he is ready, willing and able to give you as much tech support as you need. (Disclaimer: Charlie's facility is just a bit north of me, and small world that it is, he worked for the same company as I did many years ago.)
When evacuating & charging the system, be extremely careful that you don't get air into the system, especially if you are charging from 12 oz cans. My low-side pressure is fine, but the high-side pressure is much too high for the R134a charge, a obvious sign that either a condenser is blocked (which doesn't appear to be the case) or that I screwed up charging the system (much more likely).
I did the all or nothing approach: Replaced the two stock condensers with Griff's new ones and added the two condensers in the LR wheel well, variable speed controller, hurricane blower, new evaporator, rcvr/dryer, hoses, pressure switch, compressor. Good luck.
I would love to get the same results your getting Pav! I'm thinking it may be as simple as finding the right shop to really put an extensive vacuum on it and then re-charge the system. I have reached out to my local PCA chapter Chairmen to see if they can help. I may also have some blockage issues and perhaps just draining and flushing the system will help. I asked the first guy who looked at it to do it and they never did.
I would love to get the same results your getting Pav! I'm thinking it may be as simple as finding the right shop to really put an extensive vacuum on it and then re-charge the system. I have reached out to my local PCA chapter Chairmen to see if they can help. I may also have some blockage issues and perhaps just draining and flushing the system will help. I asked the first guy who looked at it to do it and they never did.
I did my own on my previous car, I found it cheaper to buy a vacuum pump and a set of gauges than to pay some shop to do the work.
I ran the vacuum pump for 24 hours, let it sit, ran it for another 8 hours and confirmed there was no leaks. Then I put in the full charge of refrigerant, using the weight rather than pressures.....I think it was 3 large cans. System worked from day one and while not Griffin temperatures (Retroaire) I easily got sub-40 degree cold air out with a few degrees lower once the system had stabilized. System had a single condenser with no electric fan support and the Retroair fan of course
Ok Folks, here's an update as my AC journey is coming to a close. I brought my SC back to my favorite shop to do some work on things I just didn't have time for and as it turns out, he is familiar with the Griffith's system and is also a perfectionist so I knew I could count on him to spend the time and do it right! We decided to start the charge process over from scratch with a system evacuation and an extended vacuum. After placing the system under vacuum for 24 hours my technician recharged the system with 36 ounces of R-134A. Previously the AC specific shop I took it to first was only able to get about 24 ounces in and we all figured it was undercharged but Hi and Low side pressures dictated it was full so they stopped. There are so many miles of hose in the car, it's easy to understand how unwanted air can get into the system that a 10 minute vacuum just doesn't do it. All of sudden the system is producing vent temps in the low 40's! Holy cow, it works!! I almost fell over in my chair! My tech held on to it for a few more days for some other items and did tell me that it struggles to reach those vent temps again if the car is sitting parked in direct Florida sun all day and has a full heat soak. He hasn't given up on trying to improve the performance but he had other customer commitment and I hadn't driven the car in two weeks so I was eager to pick it up and get behind the wheel again.
Picked it up on the way home from work yesterday afternoon and with ambient temperatures around 95 degrees and 100% humidity I was getting those low 40's vent temps and I couldn't have been happier! Vent temps in traffic will rise in to the high 40's low 50's but that is to be expected. What I didn't expect and what I now have to figure out is this little quandary. The vent temps seem to stay steady in the low 40's and then they will start to rise and in 30 seconds the vent temps hit 60 degrees only to start dropping back down into the low 40's again. It takes a minute or two to go from 40's to 60 and back down into the 40's again. This cycle seemed to happen about every 10 minutes or so for the last 30 minutes of my drive home. All while speed and RPM stayed relatively consistent. I am wondering if anyone has an opinion on what might be causing that or what it might indicate?
I will say this. I am still so pleased with how much more comfortable it is with the Kuehl system then without it and I'm very glad I spent the time and money to install it. Remember I am a novice who wanted to install a very complicated after market AC system in a 42 year old car and my experience in no way should deter someone from going the Griffiths route. I may still have some trouble shooting to do but I know this thing works and it's the best option out there to keep these car's cool in the summer. I live in tropical jungle under the worst conditions for an AC system and I couldn't be happier. If anyone has suggestions on troubleshooting my quandary please feel free to chime in
I thought that a possibility as well but that quickly? It literally goes from 40's to 60 and right back down again in a matter of 1-1/2 to 2 minutes. The more I think about it the more I think it might be the high low pressure switch. I think what I need to do is when it starts, pull over, jump out and see if the clutch is spinning or not? Then perhaps it has too much or too little refrigerant?
I just took my to a quality shop and have been paying the bill. Vent temps will get into the 40's for a bit then system freezes up. The temps go up quick. Added the fender evaporator. The jury is stil out. Temps only got to 60 then headed up.
If your system is charged with 36oz. of R134 it is not undercharged or overcharged. I would investigate the thermostat and the location of the probe. In my 1988 I found the freezing point at the mark next to the coldest setting. When I set the thermostat at a warmer setting (counterclockwise) because the cabin is too cold I can hear the system go on and off. The vent temps never fluctuate as you describe because air is always flowing through the evaporator. You describe a condition where the air flow through the evaporator is blocked by ice.
Crracab, I appreciate the advice. I didn't get a chance to dig into it this weekend. I'll dig into it this weekend and we'll see what happens. I am skeptical that it's freezing and then thawing so quickly but it's absolutely worth looking at.
07-26-2021, 05:11 PM
