Start another Air Conditioner Debate

[speedman]

I have been working on my 79SC A/C unit. I want to keep it stock until I have got all the cooling I can out of the system. I done the following stuff:
1) replaced the piston York compressor with a Nippon Denso rotatory compressor
2) Replaced the hoses with new barrier hoses
3) Replaced the receiver dryer
4) Added 3 127CFM SPAL fans to the rear condenser
5) Added a 300CFM centrifugal fan to the front condenser and enlarged the
opening and added a baffled dust work to spread the air flow over the coil
6) Charged the system with enviro-safe R12 replacement

I am getting 48-50 degree F at the vent. I want to get suggestions on what I can do to improve the system without too much more expense.

[wwest]

Originally Posted by speedman

I have been working on my 79SC A/C unit. I want to keep it stock until I have got all the cooling I can out of the system. I done the following stuff:
1) replaced the piston York compressor with a Nippon Denso rotatory compressor
2) Replaced the hoses with new barrier hoses
3) Replaced the receiver dryer
4) Added 3 127CFM SPAL fans to the rear condenser

127 CFM seems low, Spal P/N?

5) Added a 300CFM centrifugal fan to the front condenser and enlarged the
opening and added a baffled dust work to spread the air flow over the coil

6) Charged the system with enviro-safe R12 replacement

I am getting 48-50 degree F at the vent. I want to get suggestions on what I can do to improve the system without too much more expense.

Pictures..??

1.) Window tint.

2.) Trinary pressure switch, Red Dot, to power the fan(s), front included, ONLY in the optimal heat transfer range.

3.) Add the cabin heater blower to the "mix"...

[Algernon]

Sounds good, Speedman.
How about some more information and pictures about #5, the improvements to front condenser?

[wwest]

Kuehl could best answer this, but the below implies to me that you may need a TXV calibrated for the new refrigerant. Speaking of which, why did you not use R-134a..?

Enviro-Safe FAQ - Can I lower “head pressure” in my air conditioning system by using Enviro-Safe™ Refrigerant?

[wwest]

This bit of "double-speak" REEKS of Snake Oil...

Enviro-Safe FAQ - Is it legal to use Enviro-Safe™ Refrigerant in automotive applications?

[GH85Carrera]

They best way to get the air to be colder is more condensing. Did you pill the evaporator and clean it? My original one was filthy and gross. I just replaced it with the Griffith's unit when I did my upgrade.

Any additional condensers you add will help a lot.

[NathanR]

My plan is to stuff another condenser in the rear left wheel well, either in front of, or behind the wheel. If that doesn't get it, I'll do both!

Oh, and, make sure the PO hasn't stuffed a stereo amp under the passenger floorboard, right on top of the cabin blower inlet. I was poking around under the dash of my 911 today and pulled the floorboard out. There was an amp sitting there. I've owned this car for 5 years now and always wondered why the airflow volume at the vents was so crappy. Maybe now, slightly less crappy...

[Jack Stands]

In addition to the Porsche, I also play with a 1975 GMC Motorhome. They also have issues with an inadequate AC system from the factory. I and many others have replaced the original R-12 with a refrigerant called Duracool, which is a propane based product from what I've been told. It seems to cool much better than the R134a, and works in the motorhomes quite well.

I have no knowledge of the issues or legality of changing out the refrigerants, but it may be another possibility. Hopefully someone with more knowledge can chime in as we all like cool air in the hot, humid summers!

[Bob Kontak]

Originally Posted by Jack Stands

Duracool, which is a propane based product from what I've been told. It seems to cool much better than the R134a.......

I have no knowledge of the issues or legality of changing out the refrigerants,

Wow - it is not legal. hydrocarbon base/flammable. EPA is pretty serious in their write-up.

Legal Status of HC-12a ®, DURACOOL 12a ®, and OZ-12 ® | Alternatives / SNAP | US EPA

Must be cooler because it has a low boiling point like R12. Not sure.

R-134 is legal to put in but not legal to remove (without EPA certification)

R12 can be purchased (Ebay has plenty for sale) with a MACs 609 certification - an on-line, open book test - probably under $100 for the test. Never expires. The MACs 609 certificate allows you to put R12 in but not take it out (recover).

To recover refrigerant there is another test that is a bit more real and I believe you have to prove you have acceptable recovery equipment.

FWIW - I just bought a 30 pound jug of R134 for under $100 at Advance Auto. It was a rate for a commercial account. I just asked them for the discount. That takes the $14.99 per 12 oz individual can down to $2.50 per 12 oz can.

R12 can be had for $25-40 per individual can or up to $500 for a 30 pound jug. Now ain't the time to buy yourself the big stash. October maybe prices will soften but I am not sure. I got a "new" tank of DuPont Igloo R12 two years ago for $350 but had to pick it up as the seller did not want to hassle with shipping docs.

[JAR0023]

How hot is the ambient temp when you measure 50* at the vents. If it's 100* out and you are getting a 50 drop in vent temps you are doing pretty good. I'm running ES12a in my mostly stock '86 and I see a quick 45-50* drop from ambient. On a long highway run vent temps will creep down colder given enough time.

+1 on cleaning the bottom of your evap core. Mine was nasty. Also make sure you have something to seal the sides of the evap core to the box. You want to force all the air through the core and not around it.

With the tiny vents in your car you'd probably notice a difference either pulling the bowtie vent or adding a directional vent. The way the hoses run in the trunk mean the bowtie gets the best shot of cold air straight off the blower. Once you've maxmized the cooling of your system start looking at increasing airflow.

If you are running ES12a I'm assuming you did some homework. Ignore the naysayers. It works as well or better than R12 and keeps overall system pressures at or below R12 pressures. It's cheap and DIY friendly. You can try Industrial 12a which is supposed to cool a little better at the expense of slightly raised pressures.

The rear condenser fans work at idle and low speeds, but don't do much at higher RPMs when the engine fan has overpowered them. You can use foam to seal your rear condenser to the engine lid. This will force all the air coming through the grill to pass over the condenser and not around it. Be careful with this one. I found this caused my engine temps to increase and ended up removing the foam seal. The couple of degrees lower vent temps weren't worth the trade off.

One thing that bugs me and I don't have an answer for is that with the evap box and long air hoses in the trunk you lose efficiency and end up cooling the trunk to an extent. If you come in after a drive with the A/C and pop the trunk and pull the carpet you notice the evap box and a/c hoses will all be very cold and wet with condensation. You trunk will be cool as well. Some folks insulate the evap box. I think insulating the air hoses would help as well but you have to deal with the condensation. -J

[speedman]

Sorry for not responding sooner. To address te issue of the enviro-safe. The website is Environmentally Friendly Refrigerant and Automotive Fluid Products - Enviro-Safe, Inc. You can check it out for yourself. I wenl to the EPA website to check it out

[Chuck.H]

>>> I want to keep it stock; so far I've changed A,B,C... X,Y,Z :-)

I greatly increased the airflow in my '89 A/C by fiberglassing a blower motor and housing from a 2000 chevy blazer to the airbox cover I got at the parts heaven swap meet a few months ago. Not pretty but the airflow is incredible.

Chuck.H
'89 TurboLookTarga, 360k miles

[ljowdy]

A few years ago, I bought everything,,,,, condenser, receiver/dryer, barrier hose, compressor,evaporator, variable speed fan etc etc. from Kuehl including a 2nd condenser with a fan that mounts in the left rear wheel well and I"m using R12. The air in my 1973 is cold and works well.

[GH85Carrera]

Originally Posted by ljowdy

A few years ago, I bought everything,,,,, condenser, receiver/dryer, barrier hose, compressor,evaporator, variable speed fan etc etc. from Kuehl including a 2nd condenser with a fan that mounts in the left rear wheel well and I"m using R12. The air in my 1973 is cold and works well.

Yep, Griffith's stuff works just as advertised. No snake oil, no buyers remorse. Just cold air. Not cheap, but neither is owning a Porsche.

[Jdub]

You might send a note to Rob Siegel via a PM on this 'Board (RSiegel) or contact him via http://www.robsiegel.com. He went through this process on his '82 SC and has a lot of background in fixing AC.

[speedman]

here are the pictures of the front fan unit

[speedman]

here is another picture