are these pressures at idle or are you reving the engine up.

2 condensers or 1

stock system

have you driven it to see how it does.

" 88911coupe"

2 condenser min.

I have both original condensers plus an additional large one with a fan in the rear wheel well. Charge was done at idle with large fan on rear condenser. After they charged it up I drove around a while but vent temp never dropped much below 60. Also have new upgraded evaporator, all hoses new as well.

^^^

You should have ballfreezing a/c given your setup - mine is very similar, I just serviced the system yesterday (upper 90s in my garage) and got vent temps of 27.6 degrees with evaporator blower on max (pressures of 28 and 220) - seat back temps in the 50s, etc, . . . temp and pressure readings at idle and with windows closed (the Griff method for charging that works perfectly). The cabin was so cold and dehumidified, relative to the outside air, that it was shocking.

I know this is very frustrating, but your system has a problem, likely simple, that just needs to be found. Have you tried a new expansion valve, just for shiits and giggles?

Before you start replacing parts and writing a 100 page thread.....

Stick a digital thermometer in the evap core to observe what its temperature is.

In general terms, with a normal operating system your evaporator outlet hose fitting will be sweating or frosted on a good system.

If your evaporator core is near freezing and you are seeing much higher vent temps then inspect for air leaks between the plastic evaporator outlet tube and the center vent.

Well I've already replaced pretty much every part already...LOL. However I did just do as you suggested and I'm getting 55-56 degree core temp which seems to be in line with 60 degree vent temps. The inlet pipe to the evaporator it very warm to the touch and the outlet is very cold and sweating a lot, but it's definitely not frosty. And thanks for taking to time to help.

88991,

I'm reading alot of your observations, yet can not see all the data from one session, reading bits and pieces from multiple sessions.

Ideally, what I'd like to see is the following:

1) Proper evacuation. And, advise how you did it, and how many microns you got down to immediately before charging, not the night before.
2) Amount of R134a in the system measured in ounces or grams, not cans.
3) What is the ambient temperature average around the car (not on weather channel).
4) What is the low and high side pressure at idle, and without any fans on condensers that are not on the car when you are driving.
5) What is the evap core temperature.
6) What is the center vent temperature on fan speed 2 or half fan speed
7) Windows up, fresh air controls to the left, heater boxes closed,
deck lid down resting on the service hose.
8) Which evaporator do you have and did it come with a new TEV attached.
9) How much of what type of refrigerant oil is in the system, in ounces.
10) Is the front condenser blower motor running when the compressor clutch is engaged, and if you have rear fender condenser and it has a fan is the fan running as well.
11) Post a picture of your rear fender condenser so we can see which way the tubes run and how it is plumbed.

what are your pressures at 2k

Ok, will try to get Kuehl answers to all those questions. I think I can address them all except the Micron gauge reading. However, when I did this same process last year I had a functioning micron gauge and the reading, IIRC, were where they needed to be. The issue is the gauge died at some point over the winter and had been returned to be replaced. One thing I need to point out is that even when I took it to a good AC shop they mysteriously got the same end result as me. I will get all the details and post them as soon as possible.

Make sure the hose routing or flow through the condenser is correct.
the flow out of the compressor should go into the top of condenser to condense the 134 into a liquid coming out of the bottom of the condenser. I did a car backwards once and had a similar experience.

OK, saw comment about orientation of new/additional condenser, here is a pic of how it's installed. Do I have in set up wrong? The "tubes" are a little hard to see but they are at the top. The smaller aluminum line is coming from the rear deck lid condenser.

http://forums.pelicanparts.com/uploa...1531585095.jpg

"11) Post a picture of your rear fender condenser so we can see which way the tubes run and how it is plumbed."

Appears you have a piccolo tube and fin design, more efficient than a standard tube and fin (alike what is stock on a deck lid condenser), we used them years back and they can do well, if you orientate them properly.

Looks like your 'tubes' are running vertical, up and down. Ideally the condenser should be orientated so the tubes are horizontal, left to right or right to left, with the inlet from the deck lid condenser at the top and the outlet at the bottom. This is not to say the way you have it... you could achieve some cooling performance, however currently it is not ideal.

When the refrigerant leaves the compressor it is a high pressure 'gas' and as the condenser removes the heat from the gas the change of state is from a gas to liquid.
With the refrigerant tubes in the condenser, as you have them, vertical (up and down) its difficult for the liquid to move through the tubes; takes more energy to move it up and down rather than left to right or right to left like going down a set of stairs in simple terms.

http://forums.pelicanparts.com/uploa...1531737222.jpg


I can't see the size of your fittings, however the largest fitting (usually a #8) is the inlet and the smallest is the outlet (a #6). If they are both #8 then you just need a transition fitting from 8 to 6 on the bottom outlet manifold.


http://forums.pelicanparts.com/uploa...1531737636.jpg


I won't say your issue of a warm evaporator core is related to above just yet, however you got a lot of non kosher stuff going on. Might as well get your ducks in order in addition to providing observations (data) from one evac, charge and test session.

Thanks for the instruction on correct orientation. I'll tackle that and see what happens with the performance once that's done. I guess too much to hope that will solve my issues but at least I'll know it's installed correctly and works efficiently.

Is the fan pushing or pulling?
Coolest air should meet the leaving refrigerant.

It is "pushing" the air into the condenser.

Ok...was planning to start ripping the condenser out to reposition it and decided to make sure and provide Kuehl the requested items. I know I need to re orient the condenser but I suspect that may not be the root cause of my issue, which is excessive high and low side pressures with a way undercharged system. However, if this condenser position is likely the cause I'll get right on that.

OK...I know everyone has been waiting breathlessly for my annual/summer AC meltdown so here we go...LOL! I wanted to check one thing before I moved ahead. I've vacuumed my system down several times and regularly get to low 300's Microns which I "THINK" is sufficient. It holds vacuum for hours. I have some pics to show the results and set up. Note that the vacuum gauge shows -27.50 at 290 Microns. I have not adjusted to needle to re zero. Here is my question. I hooked up one can of R134, purged the line completely, and let if flow slowly into the low side. IIRC Griff said my static pressures were too high when doing this in the past, indicating ambient air in system and I'm get about 95-100 psi again. I've attached some pic to see if I've done anything wrong and to get opinions. I have not started the car yet to add more cans, wanted to get opinions if this indicates I ALREADY have ambient air in system.
Can't upload pics!? Will try to add in separate post.

Here are the pics I was unable to add before. Its the gauge set up, Micron gauge and vacuum level that only goes to 27.5 even at 330 microns (have had it below 300). The static pressure after using a single can of R134 emptied into low side (after purging line) is 90-100 PSI depending on ambient temp. Does this pressure indicate ambient air in system? Not sure how that's possible considering the level of evactuation and purging the line before adding the can.
http://forums.pelicanparts.com/uploa...1596570291.jpg
http://forums.pelicanparts.com/uploa...1596570291.jpg
http://forums.pelicanparts.com/uploa...1596570291.jpg

1) Connect your micron gauge directly to the pump. Run the pump for about 10 minutes. Record the micron level.

2) Disconnect the service set hoses from the car. Leave the micron gauge attached to the service set as you have it in the picture. Run the pump for about 10 minutes.
Record the micron level noted on the micron gauge, and the inches of mercury noted on the low side analog gauge.

3) Disconnect the blue low side service hose from the low side connection port of the service set. Attach the micron gauge to the low side connection port on the service set. Attach the yellow hose from your vacuum pump directly to the 2 purpose port on the center of the service set manifold. Run the pump for about 10 minutes.
Record the micron level noted on the micron gauge.

4) Disconnect the micron gauge from the low side connection port of the service set.
Re-attach the blue low side service hose on the low side connection port of the service set. Leave the yellow hose from your pump connected directly to the 2 purpose port on the center of the service set manifold.
Make before you turn on your pump again be sure the gauge is 'seeing' the ambient pressure around the gauge, meaning you have allowed air to enter the gauge to reset the gauge to its current "zero". Document if the low side needle is pointing on the center of the zero or how much north or south of zero. Then, run the pump for about 30 minutes. Using a 5x magnifier, closely look a the needle on the low side gauge and provide your best estimate as to which 'hash' line scale the needle is most directly over. Record what you noted.

Could it be just a defective new exp valve?

Thank,s Griff, I was able to do the first 3 so far. Here are results;
1. 59 microns
2. 290 microns and gauge was dead in middle between 25-30 so 27.5.
3. 270 microns
4. Will try to get tomorrow

I would make sure that the condenser is not dirty and plugged, so that your removing the heat, and getting a full column of liquid back to the expansion valve before it enters the evaporator. there is so much to this refrigeration stuff.

Thanks for the suggestion, the condenser has been removed, cleaned up and reoriented Last summer based on Griff’s guidance. Unfortunately the results were the same. As far as Ganum's suggestion regarding the expansion valve, I have wondered that as well but the symptoms seem to indicate ambient air in the system. I'm quite willing to replace the TXV at this point since I cannot imagine how I've gotten air in the system after doing this carefully so many times over the years.

If you go and do that, then while the valve is out disconnect the lines at the comp and flush the lines out with freon. Helps get air out and verify there is flow.

I have practically never seen a new expansion valve fail straight out of the box .. I have had to adjust a few, when they weren’t feeding properly, but that is rare also. What does your evaporator look like when you think your fully charged . Also make sure and purge your refrigerant line, before adding liquid refrigerant after a good vacuum below perhaps 400 microns .. if your not purging refrigerant line before adding refrigerant, you will introduce moisture. You might want to triple evacuate with nitrogen .. I realize you may not have nitrogen .. but that would be the best action . Do these systems have a receiver and a sight glass ..

Yea, when I recharge my 911 I do the belts, suspenders, staples and glue total overkill to be 100% certain there is zero moisture in there. I have a four valve manifold gauge set. Obvious high and low connection, one to the vacuum pump, one to the refrigerant tank or nitrogen tank. All lines are purged or vacuumed.

I start with a two hour vacuum pump run, shut it off, and let is sit overnight. Next day is pressurize with dry nitrogen (instead of the refrigerant tank) to 200 PSI, and check for bubbles in the connections using soapy water. Pull a two hour vacuum, pressurize with nitrogen to 200 psi. Leave that overnight. Check to see the pressure is the same. Vacuum again.

Then I change the oil in my vacuum pump, pressurize with nitrogen, then vacuum one last time down to the 300 microns if possible, then fill slowly with gas refrigerant. until it stops going up in pressure. Then I start the car, and pressurize to the proper pressures with a pressure chart and ambient air temps. I have four condensers, and all new hoses and the Griffith's evaporator. I really have no clue how much to add by weight. I get the pressures to my optimum numbers. Unhook, and go for drive.

Ahhh COLD air.

If you look around on YouTube you can see a guy use a bell jar to put water in a little container, pull a vacuum and most of the water boils off, but there is a large hunk of ice left. It sits in there for a long time before it sublimates, and puts moisture in the system. I am just paranoid that with the miles of rubber hoses ice is lurking. I kill it dead with my overkill system. A nitrogen regulator and rented tank of nitrogen is not very expensive, and beats wondering if there is moisture left behind.

One simple question ... is there a sight glass and a receiver on these systems .. I have an 82 sc.. and I can see the sight glass on my driver side fender ..

Glen you may be right. I vacuumed this thing down, let it sit for hours/days, vacuumed again and again. No leaks that I can find and could regularly get to low 300 micron range. It seems odd that there would STILL be water or ambient air in the system after all that, but what do I know. What's strange is it seems that several owners have been able to successfully recharge their systems without going to extremes as far as the evacuation process. I don't want to rehash things but I also had a setup where I could vacuum all hoses between cans and got same result. Finally, I highly regarded AC shop here in Dallas did a vacuum and recharge with the identical results as me. I still need to get Griff #4 on the list and will do that after work.

There is a sight glass, it is not easy to see. It is on the receiver dryer, and often rotated back against the body. Mine had a plastic cap on it to cover it. It is really not that useful of a tool on the 911. The pressures or the weight of the refrigerant is a much better way to charge it.

On my car I have to loosen the clamps that hold the receiver dryer in place, and physically rotate the unit. And remove the front tire to get my head in there to see the sight glass. And all I see is liquid and some bubbles flowing through.

I don't know if you got to watch the shop do the AC work. Even long time pros just can't grasp how many feet of rubber hoses there are. One of my friends is a pro that works at the local dealer. He helped me do it the first time. He though I was nuts to go through my many steps. But he is paid by the job, and speed is most important. Three days to do a recharge is just a possibility in the real world or professionals.

I don't think its a leak.... there is so much to check. I am a refrigeration mechanic by trade and have been working with all types of systems for over 20 years . you could have a bad compressor , who knows. you need a full system check. There is ways to check all of this? there is a lot of wrong information out there? anyways good luck!

Just quick overview, compressor is new and problem is same before and after new compressor. AC was decent before but decided to go full R134 conversion and has been PITA ever since. All parts brand new, hoses, evaporator, R/D, compressor, extra condenser with fan, all connections. Decklid and front condenser are only original parts and were flushed and dried thoroughly.

It does make me wonder if one of the hoses is pinched or restricted somehow. The route from front to back does go through some tight places.

Anything is possible.... but a restriction or a pinched hose would create no suction pressure and you would run in a vacuum .. he has suction pressure ..

Ok great so it sounds like it’s a refrigeration issue and not a part that is potentially defective , I wouldn’t change anymore parts until it’s fully confirmed that it is a defective part .. there is some things I have in mind to check.. but not sure if it’s possible to advise here ? ✌️

Was the liquid line filter drier changed

What do the vent temps get to when you drive it? What about at 2,000 RPM?

1) Wow, that is a good pump. By the way, what is your altitude above sea level?

2) Hhmmm, well 290 microns equals 29.91 inches of mercury.

Are you using any hoses that have one way check valves ?

Yes it will be interesting to read what item "4" above is.

Sorry for delay, have part 4 data.
when the gauge is at rest "zero" it is on about plus 2 1/2 lbs, maybe a TINY amount less. After running for about 30 minutes it is just shy of dead in the middle of the 24 and 25 lb hashmarks. If I let it run 3-4 hours is is perfectly centered between 24 and 25 (24.5 lbs) and never goes further regardless of how long it's run. It will hold that for hours.
Regarding other questions the r/d has been changed and the vent temps in prior vacuum recharge attempts it never got below the upper 50's then would climd to low 60s. Out of curiosity I ran it after only putting 1 can in and am getting mid 70s at upper 90's ambient. Core temps always a couple degrees cooler, which makes sense. I noted the pressures when I ran it the other day and was as follows
30 seconds 12/130
60 seconds 15/148
90 seconds 20/150
2 mins 20/150
3 mins 22.5/175
4 mins 22.5/180
5 mins 24.5/190
6 mins. 26/200
note that this was with 1 12oz can in the system. I have not added any more R134 yet.

I think next step is to add 2nd can of R134 to see what happens. Was just curious to see if any of the above results indicate ambient air ALREADY in system, in spite of what appears to be very well vacuumed system and careful recharge process. If this fails...again...will try a new TXV. They are not expensive and maybe I'll see something when doing that work that will indicate what's wrong.

OK...didn't want to start ANOTHER "my ac sucks" thread. Some have said its helpful (critical?) to purge ac system with nitrogen so I went out and got a tank and regulator. Only problem is I can't find detailed instructions on how to do it. I have a pretty good idea but wanted to make sure I was on the right track. I found this video and it seems pretty straightforward https://www.youtube.com/watch?v=E_UF7XtW8qI. He's got a very high end 4 hose gauge so I'm going to just use two hoses with shut off valves on the yellow/common line. I like this since its moving through the system as opposed to just emptying into the vacuum. Hopefully this addresses my ongoing issue...just in time for fall weather...