How do I recover/evacuate the R12 in my system so I can....

white99c2 · 01-27-2010, 10:20 AM

Install a new Kuehl evaporator in it. The replacement of the evaporator looks pretty straight forward. I'll play it safe here, if anyone can could you write up a step by step on how I should tackle this project. I think that this is the key to get colder temps in the cabin with my R12 system?

Kemo · 01-27-2010, 12:20 PM

Might be best to have a local A/C shop evacuate for you. you will need to have it vacumed down and refilled anyway since replacing the evaporator will most likely introduce some moisture in the system.

white99c2 · 01-27-2010, 03:16 PM

I know that, the guy that does the work for me wants $650 to do it for labor I have the new evaporator. I know I can do this, what tools, equipment do I need and how do I do it? Please post.

supernovatx · 01-27-2010, 04:29 PM

The advice Kemo gave is good unless you plan on investing in a/c gauge set, vac pump, oil, suggest a new dryer since your in there, R12, seals, household fan, and several hours for a proper evacuation. You're looking at quite the initial investment. I considered all this when I was about to install my system. I had all the parts, just not the tools. In the end it was cheaper and easier to take it to the shop and have them do the evac.

Understanding your desire to do this (as I did) I would suggest searching the internet as a/c systems are a/c systems. I also think you should call a couple of different places as that sounds really high unless the shop is replacing your seals and dryer.

Know this isn't what you wanted but I'm bored.

Barrpete · 01-27-2010, 05:04 PM

The $650 includes replacing the evaporator? Or just evacuating the system?

If it's just to evac the system that's outrageous. You should be able to find someplace that will just evac the system for you. Then you can do the replacement and take it back to have the system recharged. You probably can't recharge it yourself unless you have a license to buy more R12 or know someone with a license who can buy it for you.

Since you have a Keuhl evaporator you've seen Griffiths site which has a lot of good info. Also check here, these guys are in Phoenix. Automotive Air Conditioning Parts & Equipment - WWW.ACKITS.COM
Not Porsche specific but lots of good general info.

80-911SC · 80-911SC's Garage

if i am reading this right he already bought the evaporator .

the 650 is probably to do the job.

just go to another shop and ask them to evac your system , you may be able to talk them into letting you bank your freon with them for a bit (use some charm) run home swap it out and go back , thats the best advise.

Home evac , good luck equipment not cheap and its not legal without a license in most states. I know last i heard in Cali freon was running in excess of 60 a lb and i think our cars if fully depleted are over 3 lbs.

Best of luck with this , aslo of note it does not take a Porsche certified mechanic to evac and fill , just a standard GED carrying ASE a/c tech can do it, try a smaller shop and try the charm thing ..............

budge96 · 01-27-2010, 08:18 PM

Rob unless your system is pristine and airtight (most original '79 SC units are not) you likely
have little if any freon/R12 to speak of in your system.
The important point of course is the ability to hold a vacuum or charge for any extended period
of time. Earlier systems were meant to breath and had pourous lines to allow for this..
Vacuuming the system down does require guages and lines and a cxompressor pulling not
pushing ( I've seen small used refrigerator compressors used in reverse work fine) Once you've
determined you have sufficient vaccuum held it can be charged again with R32a.
it may be the best policy to get advice from a trained mechanic versed in the working of
foreign car a/c systems but it can be done with some research and reasonable knowledge , Bert

mthomas58 · 01-28-2010, 04:57 AM

Quote:

Originally Posted by azrob226

Install a new Kuehl evaporator in it. The replacement of the evaporator looks pretty straight forward. I'll play it safe here, if anyone can could you write up a step by step on how I should tackle this project. I think that this is the key to get colder temps in the cabin with my R12 system?

Rob, what is the condition of your A/C system now and what are you attempting to acomplish? If your system is properly charged and functional, changing the evap to a higher efficiency serp unit will improve performance, but if you are looking for sustained lower vent temps in your extreme climate in AZ you're not going to get there with an evap swap only. The key to better performance to the stock system is addl condenser capacity.

If your project is limited to replacement of the evaporator only, I'll echo what has been recommended. Find a shop that will charge the system for you with R12, have them evacuate the system, take the car home and do the evap job and then have them recharge if for you. They might give you a break on the recharge cost due to the recovered R12 but I wouldn't count on it. To do the entire job yourself, you are looking at a substantial investment in tools & equipment on top of exorbitant cost of R12.

You'll find all of the evap replacement DIY info you are asking for and more in this thread. Get comfortable first, it's a long thread!

A/C Upgrade Project starts tomorrow!

white99c2 · 07:01 AM

1- My system was fully recharged with 48 oz of R12 in July of '09. I've run it all winter to keep the seals from drying out and the sight glass in the dryer still shows the ball floating on top so if any R12 leaked hopefully it was not a lot.

2-In the heat of the summer on 110 degree days my car would drop the vent temp to 60 degrees, shedding a 50 degrees differential.

3-I added a 9 inch fan/relay under the rear condenser that is sucking into the engine compartment, works like a charm.

4-I replaced the front condenser fan motor and bolstered it with 3 additional small computer fans sitting right on top of the condenser, I can really feel it pushing air through the condenser now.

5-I added a 125 CFM fan/relay under the passenger floor board to assist with return air back to the evaporator.

6-I manufactured a duct/vent from a 911 center dash vent I picked up on eBay for $9.00 and installed it out of the location of the bow tie.

I can get 60 degree air out of a shady garage. Heaven forbid I go out, park the car with a sunshade behind the windshield and my dark 25% tinted windows. The car heats up like an inferno and it will now blow 70 degrees until it cools off maybe after driving on the freeway for 30 minutes or so. In the cool Arizona 100 degree dark evening hours I can get a delivery temp of 55 degrees.

My wrench has assured me a serpentine evaporator will knock off 5 to 10 degrees of temperature, is he right?

To answer your question, yes my A/C system is in good shape, as good as possible in my 31 year old beauty.

donald · 01-28-2010, 07:08 AM

Recently, I needed to remove the evaporator on my wife's Acura to replace the blower motor.
The local A/C shop evacuated the A/C system. Now that the evaporator is back in place I will return to the A/C shop and they will recharge the system. I told the shop it would take about 2 weeks for me to return and they were okay with the timing.

When they evacuated the system, they measured the amount of "freon" in the system. When I return, they will recharge the system with whatever freon they have on hand. I found out that the Acura will need an additional 5 ounces of freon when they recharge it.

They told me the total bill would be $100. So for this price, my system was evacuated and fully recharged. Of course, I did all of the remaining labor (20+ hours of work).

Good luck.

white99c2 · 01-28-2010, 07:13 AM

911pcars · 01-28-2010, 09:14 AM

Looks "cool". Best wishes on the project.

Sherwood

mthomas58 · 01-28-2010, 09:18 AM

"My wrench has assured me a serpentine evaporator will knock off 5 to 10 degrees of temperature, is he right?"

Check out the test results here:

Porsche 911 evaporators, Kuehl 911 930 Serpentine Evaporator comparison tests.

BTW, very nice looking car!

mthomas58 · 01-28-2010, 09:23 AM

Quote:

Originally Posted by donald

Recently, I needed to remove the evaporator on my wife's Acura to replace the blower motor.
The local A/C shop evacuated the A/C system. Now that the evaporator is back in place I will return to the A/C shop and they will recharge the system. I told the shop it would take about 2 weeks for me to return and they were okay with the timing.

When they evacuated the system, they measured the amount of "freon" in the system. When I return, they will recharge the system with whatever freon they have on hand. I found out that the Acura will need an additional 5 ounces of freon when they recharge it.

They told me the total bill would be $100. So for this price, my system was evacuated and fully recharged. Of course, I did all of the remaining labor (20+ hours of work).

Good luck.

And, there are no guarantees on what they put back in - could have been other type of refrigerant evacuated in the recovery machine and your R12 may now be contaminated which will degrade performance. A/C purists favor virgin refrigerant. Sound like a real A-hole, don't I?

white99c2 · 01-28-2010, 10:27 AM

Mark,
I've looked at that chart... do you buy into it is my question.

Here is something I noticed this winter, when driving I can feel the cold outside air coming out of the A/C center vents. I closed them using the slide regulator on the side of the vents.
If cold comes through in winter than hot must come though in summer and heat up the cool air.

mthomas58 · 01-28-2010, 01:23 PM

Quote:

Originally Posted by azrob226

Mark,
I've looked at that chart... do you buy into it is my question.

Here is something I noticed this winter, when driving I can feel the cold outside air coming out of the A/C center vents. I closed them using the slide regulator on the side of the vents.
If cold comes through in winter than hot must come though in summer and heat up the cool air.

Yes I buy into the notion that (1) a serpentine unit is more efficient than a tube and fin technology and (2) that a larger serp unit with more surface area compared to the OEM unit is more efficient. In terms of measureable lower vent temps, I don't know (too technical for me) but "more efficient heat transfer" which is what A/C is all about - definately!

Regarding your air flow in your center vents with the slide regulator closed, I don't think this is normal. You should check to see if the fresh air flappers are properly adjusted.

Welcome to the obsession!

Joeaksa · 07-31-2010, 02:11 PM

Rob,

How did this ever turn out?

Regarding the referral to AC Kits, this is run by AZ Mobile Air, down off of I-17 and Clarenden here in Phoenix. They are a pretty good shop and have had them do lots of work on my cars in the past. That said, years ago I gave in and bought my own vacuum pump (already had the gauges) and just started doing most if not all of my A/C work.

They are very good for making hoses for you, parts and so on.

They are telling me that one of the new smaller serpentine condensors with a fan will take the place of both the nose and engine hood mounted stock condensor. Not sure that I would do that but would feel a lot better putting two of the new smaller condensors in replacing the stock older style units these days. Putting a modern Evaporator unit IMHO is mandatory these days as the improvements in these systems are massive.

Joe A