18 Degrees at Center Vents!!!

[DRACO A5OG]

Hey All!

First, I want to thank Steve Wong aka www.911chips.com for helping me re-charge my AC system. Steve a Million Thanks Brother, You the Man!!!

I read alot about the controversy of using ES12, but damn I never imagined getting 18 degrees at the center vents.

Repairs:

Replaced the driver side long hose from rear condensor to front condensor with a custom order 16' hose (original length was 15'8", better longer than shorter) with a R134a rated 500 PSI and new 5/8" & 3/4" fittings, Green O rings. (note, removing the hose from the engine bay is a BIOCTH, so i cut at the leak and pulled it out from the engine bay)

Rewelded cracked male fitting with a new one at the front condensor and pressure tested at 200 PSI. (Warning, you will crack the weld if you do not have a tight enough grip, I had to resort to a vise grip, the 17MM closed wrench strip the fitting)

Replaced Receiver/Dryer with a Cheapo China made one.

Refrigerant:

2 Cans of Industrial ES12 (Only used 1 & 1/4 can, advertised at 5 degrees cooler than the regular ES12, I was a bit insecure, actually bought 6 cans)

1 Can of 4 Oz Re-Charge Oil (System Leaked out all the oil, verified by opening the OEM Denso compressor and Removing the OEM R/D also dry)

Procedure:

Placed a Vacumm at -30 degrees for about 20+ minutes, and system held! I followed torque specs on the fittings and compressor, it seemed very light but it was dead on.

Charged 4 ounces of oil

Charged 1 can of Industrial ES12 and read for the 1st time 47 degrees at center.

Charged 1/2 a can of the 2nd one but temperature went up appeared too much so we bled it out until we reached 45-47 degrees. Engine was extremely hot.

Drove on the freeway while the engine cooled down to normal temps and got a reading of 25-27 degrees. We were in disbelief Something must be wrong with our infrared temperature guage. But both of our guages were reading this craziness

Reading going home off the freeway, took another reading for the heck of it and wholy smokes 18 degrees! I had to turn her down for the first time

History:

About a month ago my system was not cooling at all and suspected my refrigerant must be low or gone.

My system had the dreaded R12 and I really did not want to go R134. So I did research and found PatrickB used ES12 and thought I give a try.

The stop leak did not stop the leak because I had a 1/4" hair line crack right where the 16' long hose bends near the driver side torsion bar end cap. I found a puddle of pine scented oil right where the crack was and also found a leak at the rear condensor fitting.

The refrigerant only lasted 1 week but it cooled nicely at 55 degress, more than I could ask for. Had a 1/2 a can left so I charged it and it cooled for another week.

Needless to say I did not catch on fire as others speculated with a volitile mix.

Finally got around to replacing the hose and R/D. Then Steve came to the rescue, vacummed and charged her.

Thanks PatrickB for the Es12 Lead and Steve especially for helping a brother out.

I may have been lucky but I am telling you even with a bad leak I had near my Extremely Hot Pre-Muffler, the ES12 was absolutely safe and so easy to work with. My contibution to keep our enviroment clean . OK, that last line was just a bonus not my intention, at $10 a can it was more financial friendly

[ischmitz]

Funny, I too worked on my A/C today albeit not in the Porsche but the ML430. The thing just stopped working this week. I went out and bought a pressure gauge and two cans of R-134a. The pressure gauge read zero on the low-pressure side. This is why the compressor did not come on. The ML has a brain that switches the compressor off when the pressure is too low or too high.

Once I filled in the two cans of R-134a (one regular and one with UV-dye) the A/C started blowing cold air again. Nothing close to your 18 degrees but I am down to 34 degrees. I also got myself one of these dual-wavelength UV light sources from work to chase leaks. So far nothing has shown up.

Ingo

[DRACO A5OG]

34 Degrees, that's Cool sorry for the pund

BTW, I also removed the lower center Bow Tie, Wow the volume of air in the cab is Great. Now my rear passanger gets cools air

[Jack Olsen]

You can't measure the temperature of moving air with an IR gauge. (Why? I don't know.) But I got 16 degree readings when I pointed my IR guage at my vent -- then I switched to a probe type thermometer and got readings that were actually credible (mid-to-upper thirties).

If it were below 32 degrees, your evaporator would ice over with the moisture in the air. The system has some kind of switch inside it to cycle off when it gets too cold.

[rnln]

Jack makes sense. My thermometer is the probe type right? We'll do it again on your car to make sure.
Below 40 is amazing already.

[Jack Olsen]

Still, it sounds like your AC is doing really well.

[fintstone]

Originally Posted by Jack Olsen

You can't measure the temperature of moving air with an IR gauge. (Why? I don't know.) But I got 16 degree readings when I pointed my IR guage at my vent -- then I switched to a probe type thermometer and got readings that were actually credible (mid-to-upper thirties).

If it were below 32 degrees, your evaporator would ice over with the moisture in the air. The system has some kind of switch inside it to cycle off when it gets too cold.

Yep. Low to mid 30s is good...18 degrees is broken. Use a thermometer. If you have plenty of cold air and it doesnt freeze-up and cut out...you are probably in good shape...and just not getting a good read.

[DRACO A5OG]

Originally Posted by rnln

Jack makes sense. My thermometer is the probe type right? We'll do it again on your car to make sure.
Below 40 is amazing already.

Sounds good, but my IR guage hit the vent housing so I hope is just an error and not too cold to freeze the evaporator

Thanks Jack for the heads up.

[efhughes3]

What Jack said. You're simply measuring the temp of the vent material. If you want to measure air temp accurately (and as importantly, quickly), get a foodservice-type digital themometer. I've got a $200 Accutemp model that we used to rep, and it has a nice delicate probe for instantaneous readings of air, liquid or solid.

I agree that anything below 40 degrees airtemp is phenom.

[rnln]

then maybe it's 18 degree. Be carefull on ice blowing to you

Originally Posted by DRACO A5OG

Sounds good, but my IR guage hit the vent housing so I hope is just an error and not too cold to freeze the evaporator

Thanks Jack for the heads up.

[MattKellett]

Originally Posted by efhughes3

I agree that anything below 40 degrees airtemp is phenom.

Ed, when you mention 40 degs, are you assuming car sitting idling or driving with lets say 2500 - 3000 rpm

I ask because I just replcaed my compressor and dryer after 2 years of no a/c, and after recharging I'm managing 39 - 40 degs when driving 40 - 70 mph. Air temp outside was 85deg. When idling in garage after driving, temp increased to about 50deg.

I have no idea what is good, because obviously it's night and day compared to no a/c.

Matt

[Jack Olsen]

It's very hard to be specific with these numbers. Even if we all agreed on 85 degrees ambient, whether the car's been sitting in the sun or has just driven out from a cool garage will make a huge difference in initial vent temps. Whether the car is moving or not is also going to be a factor in how well some condensers will work. And in modified systems, the interior fan setting can mean wildly different things in terms of how much air is being moved. The faster air moves through the evaporator, the less heat it's going to shed.

There are a lot of variables.

[3.2 CAB]

Movement of the car will be a large factor in how well the A/C will function... to a point, combined with all of the other factors already mentioned.

[T77911S]

not to burst you bubble, but 1 can of freon into a system designed for almost 4? what was your low side pressure? you also want to do all measurements with the fan on hi.

[mppickett]

Originally Posted by T77911S

not to burst you bubble, but 1 can of freon into a system designed for almost 4? what was your low side pressure? you also want to do all measurements with the fan on hi.

Actually he's not using freon, he's using ES12 http://autorefrigerants.com/co00033.htm

[kuehl]

As Jack pointed out, using an IR thermometer is not always reliable; the general problem is distortion and/or the radiance of the surface measured. For air measurements the normal practice is to use a digital thermometer. There is a range of makes and models of digital thermometers and if you want a reasonable value instrument that is accurate you may want to review a Control Corp model 4339, noted here:
http://www.control3.com/4039p.htm
This tool comes in handy for many other types of temp measurements too.

If you are getting down near or below 32F you will want to insure the thermostat is shutting off the ac compressor circuit. Here is a brief write up on the thermostat's function:

The left hand knob thermostat switch in the console functions in this manner (typical of this design for this application; no defrost function in the circuit):

How The Thermostat Switch Works
The switch has a "bellow" filled with refrigerant. The bellow has a capillary tube attached to it, open to the bellow side, closed at the other end that is inserted in the evaporator coil. As the temperature in the evaporator coil increases (warm air being drawn upward into the coil), the refrigerant expands in the capillary tube. The expansion of the gas in the capillary tube moves the bellow against a set of contacts that make or break depending upon the location of the bellow with respect to the switch, thus turning on the compressor or shutting it off.

How AC Vent Temperature is Regulated
As you turn the knob on the switch you are increasing or decreasing the distance between the bellow thus changing the min or max temperature of the evaporator coil which in turn changes the a/c vent air temperature coming into the cockpit.

Switch Temperature Ranges
The switch/bellow design "usually" has a max. cold setting of 26F (the tolerance is +/- 2) ; all numbers are in "F". At maximum cold position, fully CW - clockwise, in theory what should happen is the contacts would break and the compressor would turn off when the capillary tube sees 26F nominal. As the evaporator coil temperature rises to 33F (with a tolerance of +/- 2) the contacts would make and the compressor would turn on. As you turn the switch knob CCW - counter clock wise, you are raising the temperature at which the contacts will make and break. In the maximum cold, fully CW knob position, you can see you have potential of 24F. In that same knob position (fully CW) the compressor would then turn on when at the cap tube sees 35F. The low of 24F and the high of 35F include the tolerance noted above. As a side note altitude can affect the point at which the switch makes and breaks, meaning if you set the position of the knob at one point at a given altitude at sea level and the drove up to a higher elevation the make and break point in switch/below would change. And depending upon the year your capillary tube (or thermostatic tube) was built, it may have R12 refrigerant or it may have R134a refrigerant as its gas.

Capillary Tube Position and Contact
The end of the aluminum capillary tube, inserted into the evaporator, is sealed and crimped to form a closed gas circuit to the bellow. This is where most failures (breakage) occur from handling of the tube. The OEM incorporated into the design two protective items to help protect the aluminum capillary tube. The first is plastic like sleeve (white in appearance) which extends from the switch in the center console to near the end of the tube in the evaporator box location. The plastic sleeve protects against abrasion. And, a brass tube to help protect the aluminum tube. The brass tube, which is crimped closed at one end and has a flare opening at the entrance, is inserted into an existing hole near the front support bracket on the top case half of the evaporator box. The brass tube is inserted at a diagonal through OEM stock tube and fin design evaporator coils or vertically through serpentine design coils. The insertion depth should be to "near bottom" of the coil, however not clearly through the entire coil such as to expose the tubing to incoming "warm air". The aluminum capillary tube is then inserted into this brass tube to its bottom. The aluminum capillary tube excess coil is then secured to the top of the evaporator box using a tie wrap and positioned such that the steering shaft connecting to the steering rack will not make contact.

If you are using an alternative R12 refrigerant you will want to insure that the vehicle is labeled properly so that anyone who may work on the vehicle's ac system, or possibly the next owner, knows what refrigerant type was installed.
There are more details on this subject here:
http://www.epa.gov/Ozone/snap/refrigerants/macssubs.html

[DRACO A5OG]

Whoa! great info, Thanks Keuhl!

The ES12 works with the R12 so the OEM Denso setup will imply to any future owner that they need to use at minimum R12 if available. If one decides to go R134 it too is compatible but the valves will need to be updated and label placed by an A/C servicer. my 2 cents

[JeremyD]

is there an easy way to make sure the thermostat probe goes all the way through the evaporator core? I'm worried about jamming it too far ... (and it looks like it is not cutting off the compressor - my system freezes up on long drives

[kuehl]

Originally Posted by DRACO A5OG

Whoa! great info, Thanks Keuhl!

The ES12 works with the R12 so the OEM Denso setup will imply to any future owner that they need to use at minimum R12 if available. If one decides to go R134 it too is compatible but the valves will need to be updated and label placed by an A/C servicer. my 2 cents

Droca,

There are more than a few two potential problems you will create if you do not follow the proper procedure when doing a refrigerant conversion. This comment is not about whether or not you or any user feels ES12 works better than another refrigerant; it is not about your observations of the thermodynamic performance you may have thought you experienced. Its not about whether ES12 will ignite sooner or later than petrol. And its not about whether or not the EPA's policies are correct. It is about following protocol for a reason:

If you did not use a unique service port adapter (what you would replace with or secure onto the old R12 service port) and you added a refrigerant other than CFC (R12) or you completely replaced the CFC12, an unknowing mechanic servicing the air conditioning system on the car will assume the refrigerant in the car is CFC12. If he recovers the "other than CFC12" refrigerant into his CFC12 recovering cylinder attached to his machine the unknown refrigerant will contaminate his cylinder. If he then unknowingly uses the recovered CFC12 cylinder to recharge another customers car then he has passed along the mixed gas to that car. The point is about whether you intend to be the only person servicing your car, its about can happen and it does happen.

Mixing different refrigerant gases can adversely affect the vehicle's ac performance because mixtures can behave differently in terms of temperatures/pressures. For a technician servicing a car, with the assumption that the refrigerant is pure CFC12, who notes unusual pressures he might assume the problem is related to a component or air in the system. The time he spends troubleshooting the problem can be costly for the customer as well as frustrating for him.

Recovering unknown refrigerants can be costly for the repair shop because his dedicated CFC12 recovery cylinder is now contaminated with an unknown refrigerant; it is not pure CFC12. Today the cost of portable refrigerant identification equipment is less costly but not all service shops own them and not all recovery machines have them built in.

There is a list of protocols that should be followed to insure that: A) whomever works on the car knows what they are working with, and B) potential problems are avoided.

Two easy markers to identifying what type of refrigerant is contained in the automotive system are the service ports and the refrigerant label. Here is a link to guide you:
http://www.epa.gov/Ozone/snap/refrigerants/fittlist.html

So, on the Rennlist cousin post noted your vent temps were not 18F but rather 38F. "I used my Rnln's Food Service probe thermometer and it read 38 Degrees." What would be interesting is if you let us know the following:
1) What is the IR thermometer reading and probe thermometer reading at the same time.
2) What is the ambient (outside temperature) relative temperature when you take those readings.
3) What fan speed is used when you take the readings.
4) Are the readings taken when driving the car or sitting at idle.

Keep the change.

[kuehl]

Originally Posted by JeremyD

is there an easy way to make sure the thermostat probe goes all the way through the evaporator core? I'm worried about jamming it too far ... (and it looks like it is not cutting off the compressor - my system freezes up on long drives

This was discussed a while ago in a book written about the 911, however if you know the thickness of your evaporator core and you know the distance from the top of the evaporator box to the top of the core.... you want to be halfway into the core and not "through the core". If you are still freezin up and the thermostat side is not malfunctioning (switch side bellow and its contacts), try this:
Remove the aluminum capillary tube, coating it with thermal grease (heat transfer compound, such as something you use between your cpu and its heat sink; a trip to Radio Shack), pack the brass protective sleeve with the grease and reinsert the probe.