Condenser with integral high pressure hose? - Page 2 - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
post #11 of 20 (permalink) Old 03-06-2017, 05:19 AM Thread Starter
BenzWorld Member
 
304065's Avatar
 
Date registered: Jan 2012
Vehicle: 2011 S212, 1978 R107
Location: New Amsterdam
Posts: 222
Mentioned: 1 Post(s)
Quoted: 46 Post(s)
(Thread Starter)
Heh heh heh...
Attached Thumbnails
Click image for larger version

Name:	IMG_8761_1488806379684.jpg
Views:	33
Size:	48.7 KB
ID:	2104442  
304065 is offline  
Sponsored Links
Advertisement
 
post #12 of 20 (permalink) Old 03-10-2017, 04:10 AM Thread Starter
BenzWorld Member
 
304065's Avatar
 
Date registered: Jan 2012
Vehicle: 2011 S212, 1978 R107
Location: New Amsterdam
Posts: 222
Mentioned: 1 Post(s)
Quoted: 46 Post(s)
(Thread Starter)
The beauty of ebay...putting professional tools in the hands of amateurs like me! With this I can not only charge but measure the vacuum in microns and also measure subcooling (and superheat, but this is a txv controlled system). This will allow me to measure the ideal refrigerant charge for a 134a conversion with no guesswork!
Attached Thumbnails
Click image for larger version

Name:	sman3.jpg
Views:	18
Size:	64.6 KB
ID:	2111585  

Last edited by 304065; 03-14-2017 at 04:53 AM.
304065 is offline  
post #13 of 20 (permalink) Old 03-10-2017, 06:09 AM
BenzWorld Member
 
JS5D's Avatar
 
Date registered: Dec 2016
Vehicle: 1983 380SL
Location: Houston Texas, formally UK
Posts: 239
Mentioned: 0 Post(s)
Quoted: 87 Post(s)
Wow that is rather snazzy! I purchased my set from Harborfreight which was cheap. It does the job but I would not want to be a pro with my kit. Point is I maybe regass a car every 2 years so can not really justify going all out on the tools.

The reason I decided to do it myself (the amateur) is because I found the local professionals lacked any form or basic trouble shooting skills and kept coming up with illogical stories which involved me spending more money without receiving any assurance or in fact a working AC. Nowadays there is so much information available you can be a pro in a weekend. I know there are people the completely disagree with me so let's say it this way:

- 3 so called pro's could not (or were not willing to) fix my AC.
- I however could find the leak. I could fix the leak. I could re-gass the system safely and finally the system has been working flawlessly for 2 years+

Anyway - rant over - Good luck with your AC seems you have the situation fully under control!
JS5D is offline  
Sponsored Links
Advertisement
 
post #14 of 20 (permalink) Old 03-12-2017, 10:28 AM Thread Starter
BenzWorld Member
 
304065's Avatar
 
Date registered: Jan 2012
Vehicle: 2011 S212, 1978 R107
Location: New Amsterdam
Posts: 222
Mentioned: 1 Post(s)
Quoted: 46 Post(s)
(Thread Starter)
Thanks J5 I am going to need all the encouragement I can get!

It's a Fieldpiece SMAN3, which is basically a two port digital manifold with an integrated micron gauge and a pair of thermocouples that precisely measure temperature.

I considered going with the basic setup which is fine in 99% of cases. But I want to be sure I get a vacuum of 40 microns before I charge (an old Porsche HVAC mentor, Jim Sims, formerly of the Los Alamos National Laboratory, insisted on that level) which means using a Micron gauge. A decent micron gauge is a couple hundred bucks, so by the time you add that to the manifold and hoses I was money ahead with this eBay purchase.

The really neat thing is the thermocouples and the built-in pressure/temperature database. To measure superheat, which is the temperature beyond the boiling point of the particular refrigerant at a given pressure, you clip one of the thermocouple leads to the outlet of the evaporator, and then set the correct refrigerant using the buttons. You can see in the photo above that I have set it to R134a. The box then automatically measures the difference between the measured temperature and the "ideal" boiling point from the p/t chart. You want the refrigerant to continue to heat up after leaving the evaporator-- if the temperature is too cold you run the risk of slugging the compressor with liquid refrigerant.

Subcooling is similar, except you're measuring how many degrees cooler than the boiling point the refrigerant is as it leaves the condenser. The concern is that if it's too cold, liquid refrigerant could back up into the compressor, destroying it.

So by looking at superheat and subcooling you can tell if the refrigerant charge is too much or too little. Suppose that 10F is the right amount of subcooling-- for measured values below this number refrigerant can added until the target subcooling is stable at that number.

And of course only the subcooling method will work for a system controlled by a TXV, like ours is.

Now I need some REAL HVAC technicians to chime in!
304065 is offline  
post #15 of 20 (permalink) Old 04-17-2017, 06:51 AM Thread Starter
BenzWorld Member
 
304065's Avatar
 
Date registered: Jan 2012
Vehicle: 2011 S212, 1978 R107
Location: New Amsterdam
Posts: 222
Mentioned: 1 Post(s)
Quoted: 46 Post(s)
(Thread Starter)
The resssembly begins...got the manifold back from plating, insulated, compressor mounted to the bracket, and the whole thing in the car.

I have the "third style" bracket so no modifications to the bracket or the compressor were required.

"While I was in there" I determined to change the water pump and thermostat, cheap insurance while the whole front of the motor is accessible.
Attached Thumbnails
Click image for larger version

Name:	IMG_9284_1492436863486.jpg
Views:	20
Size:	33.8 KB
ID:	2143098   Click image for larger version

Name:	IMG_9286_1492436948813.jpg
Views:	19
Size:	34.0 KB
ID:	2143122   Click image for larger version

Name:	IMG_9312_1492437000580.jpg
Views:	21
Size:	52.0 KB
ID:	2143130   Click image for larger version

Name:	IMG_9317_1492437073579.jpg
Views:	19
Size:	58.1 KB
ID:	2143146  

Last edited by 304065; 04-17-2017 at 03:05 PM.
304065 is offline  
post #16 of 20 (permalink) Old 04-23-2017, 06:13 PM Thread Starter
BenzWorld Member
 
304065's Avatar
 
Date registered: Jan 2012
Vehicle: 2011 S212, 1978 R107
Location: New Amsterdam
Posts: 222
Mentioned: 1 Post(s)
Quoted: 46 Post(s)
(Thread Starter)
Got the system assembled this weekend...a very time consuming job.

Starting point was the evaporator core- the TXV mounts to this. I was thankful I had cleaned all the insulation off these parts when I removed the old bits. It made installation easier.

Notice I didn't say "installation a breeze." Any job that requires you to remove the steering wheel and gauge cluster and lay inverted in the car with your head next to the brake pedal is not a "breeze."

The valve went in easily, had to counterhold it to tighten the flare nuts.

I used Nylog blue (HFC-compatible) on everything. Used copper flare washers where I could, but the modern aluminum fittings don't really need them.

I had Griff fabricate a short hose to run from the manifold to the condenser. Remember from the thread title, my original condenser had an integral hose. This was a piece 16" long with 45 degree female flare fittings on the ends, clocked at 6:00. I didn't think I would get it right on the first try but I did.

So...when it was time to pull the vacuum...out comes the new pump, changed the oil to JB black gold (which is transparent) and started it up, connected to the center port of the SMAN3.

Unfortunately when I would pull a vacuum (got down into the 27s) then close a valve on the SMAN, the vacuum wouldn't hold. Now, if the car can hold a vacuum but it goes away when you try to valve it off, that means the valve is bad.

So I ordered a $30 kit to service the valves on the SMAN. It comes with new brass stems, o-rings, seats and knobs. Once that's done I will repeat the test.

I am also going to get a tank of Nitrogen for a pressure test and sweep, this should connect to the manifold directly.

When this is over I will know a bit more about HVAC! It's been fun, but time consuming, so far.
Attached Thumbnails
Click image for larger version

Name:	IMG_9370_1492995541362.jpg
Views:	16
Size:	37.4 KB
ID:	2148946   Click image for larger version

Name:	IMG_9375_1492995742143.jpg
Views:	16
Size:	34.9 KB
ID:	2148954  
304065 is offline  
post #17 of 20 (permalink) Old 05-27-2017, 01:57 PM Thread Starter
BenzWorld Member
 
304065's Avatar
 
Date registered: Jan 2012
Vehicle: 2011 S212, 1978 R107
Location: New Amsterdam
Posts: 222
Mentioned: 1 Post(s)
Quoted: 46 Post(s)
(Thread Starter)
Finally got the system charged.

Found a few leaks- I charged the system with 400psi nitrogen, up to 350psi, then used soapy water to look for leaks. System held pressure, maybe it ticked down a couple tenths, but the gauge hoses aren't perfect.
Attached Thumbnails
Click image for larger version

Name:	IMG_9543.jpg
Views:	10
Size:	106.2 KB
ID:	2175970  

Last edited by 304065; 05-27-2017 at 05:36 PM.
304065 is offline  
post #18 of 20 (permalink) Old 05-27-2017, 02:09 PM Thread Starter
BenzWorld Member
 
304065's Avatar
 
Date registered: Jan 2012
Vehicle: 2011 S212, 1978 R107
Location: New Amsterdam
Posts: 222
Mentioned: 1 Post(s)
Quoted: 46 Post(s)
(Thread Starter)
I used two and a half 12oz cans of 134a.

Original charge with R12 was 1kg or 35.27 oz. R12 molecular weight is 120.91g/mol. R134a is 102.03g/mol. Divide the smaller number by the bigger one, R134a is 84.3% of the density of R12, so you use less mass for the same number of moles of gas. So 35.27oz x 84.3% = 29.731oz of R134a as an equivalent charge.

I rounded it to 30 oz or about 2.5 cans. I used the scale I bought to balance the Porsche pistons and rods to weigh out the refrigerant, this worked fine.

51F vent temp is great, not perfect. I'll see if the charge holds then will start tuning the refrigerant level for coldest temps.
Attached Thumbnails
Click image for larger version

Name:	IMG_9572_1495919308159.jpg
Views:	14
Size:	40.0 KB
ID:	2175842  
304065 is offline  
post #19 of 20 (permalink) Old Yesterday, 10:24 AM Thread Starter
BenzWorld Member
 
304065's Avatar
 
Date registered: Jan 2012
Vehicle: 2011 S212, 1978 R107
Location: New Amsterdam
Posts: 222
Mentioned: 1 Post(s)
Quoted: 46 Post(s)
(Thread Starter)
Still dissatisfied with system performance, can't do better than 60 Degree vent temps

I charged with Envirosafe. Put in two cans

It's NOT R290-- the PT charts are different. They tell you ES is 6 oz for 1 pound of R134A.

R12 MW= 120.9, R134a MW= 102. So 840g of R134a to equvalent 1Kg R12.

6oz = 170g which they say is equiv of 1 pound R134a = 453g. So that's 11.13 oz ES or about two cans once you take into account the purge.

ES PT chart suggests saturation temp of 31psi at 0F and 173PSI at 129F.

Can't measure superheat because it's not easy to get at the evaporator outlet (it's under the dash) and the TXV will continually adjust refrigerant flow to hit target temp. Best place to measure is on the suction line above the manifold, the low side port is right there anyway.

But you can measure subcooling-- and there's a convenient spot where the refrigerant exits the condenser right before the receiver drier.

High side pressure tap is on the manifold before the condenser, not ideal. Ideal would be to have a pressure tap right before the RD in the same spot. But I'll try measuring subcooling there-- about 10 degrees should insure the ES stays liquid all the way through the TXV.

IGNORE the superheat and subcooling readings, this is the internal R134a PT chart, not the one for ES. Which is not the same as R290 by the way.

Will report back.
Attached Thumbnails
Click image for larger version

Name:	IMG_1928 - Copy1.jpg
Views:	2
Size:	2.87 MB
ID:	2534430   Click image for larger version

Name:	IMG_1929 - Copy.jpg
Views:	2
Size:	2.61 MB
ID:	2534432   Click image for larger version

Name:	IMG_1930 - Copy.jpg
Views:	2
Size:	2.76 MB
ID:	2534434  
304065 is offline  
post #20 of 20 (permalink) Old Today, 04:45 PM
BenzWorld Elite
 
cushjbc's Avatar
 
Date registered: Dec 2010
Vehicle: 1973 450 SL
Location: Albuquerque
Posts: 1,668
Mentioned: 15 Post(s)
Quoted: 376 Post(s)
Subscribed - very interested in what you come up with for Envirosafe charge numbers and performance. I also want one of those SMAN3 toys to play with.
cushjbc is online now  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Roadster Forums > R/C107 SL/SLC Class

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome