Air Con - upgrading the stock 911 set up?

[Hunaudieres]

Hello. Can anyone help with the age old question of the only under performing piece of engineering on a mid 80s 911: the Air Conditioning.  I've got the original set up in my 3.2 911, but I'll coin the term 'unreliable' to qualify it.

 

Has anyone set up the aftermarket Rennair system from the US, which looks like it replaces the OEM set up with some better parts? Any other suggestions on upgrades that can help the OEM set up perform better? Cheers

 

 

[Peter M]

I'd start here:

[Hunaudieres]

Thanks Peter. Somehow the little search bar thing didn't turn anything up in the forum when i tried. Will go through the existing thread. 

[twood]

I have had a the following 911's over nearly 20 years

'76 2.7

'88 3.2

and now a '91 3.6 964. The A/C nearly works on the current car (as long as it is not a hot day). I have spent many $'s trying to make the A/C work efficiently  on other Porsches.

 

Many years ago I was offered the following advice " If you want good air conditioning go and buy a Toyota"

[au-yt]

If I can add my 2 cents worth. classic cars were all designed to work with the 12a gas which ran a lower pressure was far more efficient.

There is a gas called supercool which is better for older cars.

I owned a late 70s Maserati and managed to get the system to work OK. Others with the same car changed the compressor and the condenser. to get the system to work to a respectable level.

If it was me and I was and might yet as a 911 Hot rod is on my bucket list. the whole system needs to be designed from scratch. biggest hassle is trying to use original parts is they just dont work with 134a gas.

The condenser on some of the early cars was mounted on the underside of engine lids, great as extra heating of the engine.

The Best solution is copy another system like the 993, I found this site a car where they put the condensor in the L/H front guard.

http://www.patrickmotorsports.com/project/1973-911-rs-pro-touring-993-36l-dme-g50-sbh/

The unit for the evaporator needs to go in the frount compartment, and using a late dash or early style underdash vents would be a nice touch.

Graeme

[Coastr]

If I can add my 2 cents worth. classic cars were all designed to work with the 12a gas which ran a lower pressure was far more efficient.

There is a gas called supercool which is better for older cars.

I owned a late 70s Maserati and managed to get the system to work OK. Others with the same car changed the compressor and the condenser. to get the system to work to a respectable level.

If it was me and I was and might yet as a 911 Hot rod is on my bucket list. the whole system needs to be designed from scratch. biggest hassle is trying to use original parts is they just dont work with 134a gas.

The condenser on some of the early cars was mounted on the underside of engine lids, great as extra heating of the engine.

The Best solution is copy another system like the 993, I found this site a car where they put the condensor in the L/H front guard.http://www.patrickmotorsports.com/project/1973-911-rs-pro-touring-993-36l-dme-g50-sbh/

The unit for the evaporator needs to go in the frount compartment, and using a late dash or early style underdash vents would be a nice touch.

Graeme

Is supercool a hydrocarbon based gas like hychill? I'm actually trying to work out where I can get the r12 pulled out and hychill added.

[au-yt]

Terminoigy confusion Supercool is acompany the gas is Hychill yes its a hyrocarbon.

Interesting article

http://www.hychill.com.au/pdf/hcramcac.pdf

 

As far as I know ( read... very little) R12 gas is not leagal to use and needs to be replaced with R134a. and now this stuff is outragesly priced.

 

I googled a few places that say they have 12a but then they say the system needs to be changes to R134a.

 

The EPA here are quite a...l about this.

 

Graeme

[Peter M]

Going 134a isn't a big deal with just a change of receiver/dryer, wiring in a pressure switch and different charging ports on the compressor required.

[Coastr]

Yes r12 is illegal in Oz yet po somehow got compliance with it. Or maybe it was all removed. It definitely is not working lol. Probably why he sold in winter.

Not interested in a r134 conversion - the stuff is expensive and doesn't work as well, and early 911 systems are marginal anyway. I plan to get the hychill r12 equivalent - at least you can keep refilling as needed.

[Peter M]

Coastr,

Please do report back on how you go with Hychill. It certainty gets mentioned enough but I'm yet to hear from a 911 owner who has actually done the conversion to HC.

I've also yet to come across a local service place that uses it.

I guess if I was really keen I could get someone to evacuate and dispose of the 134a, buy myself a set of gauges and a vacuum pump, buy a 300g can or two of Hychill (need a bit more or bit less than 300g depending on which model 911) and do it myself. Certainly doable.

However I think the reality is that many people continue to use 134a because it's convenient and irrespective of the benefits of using a hydrocarbon, it won't make up for the poor condensers (with variable airflow), evaporator, blower fan and often limited vent area in the pre 964 cars. Oh and let's not underestimate the fear mongering from the HFC producers which is still rife! http://www.vasa.org.au/perth-truck-blast-probe-recommends-temporary-hc-refrigerant-ban/

Since I am already getting down to 4 degree vent temperatures, I think the benefits of converting my Retroaire/Kuehl upgraded '85 over to Hychill would be limited to maybe 10% lower line pressure and therefore loads on the compressor and maybe cheaper future regassing only if I could find a local supplier!

So I'm keen to hear how you go!

[Glom1098]

Hi Hunaudieres,

 

For another anecdotal story Im running hychill in my 81 SC, the basic anatomy of my setup is stock although I did replace the lines with barrier hoses in case I ever change over to r134 and have a rennaire pro cooler instead of the stock receiver/dryer which you will need to replace anyway. The only other change from 911 stock is I adapted a carrera pump and pump stand instead of the standard massive york pump, yours may already have it fitted if its a carrera.

 

Your system will have been setup for R12, so if you change it to r134 without changing the hoses to barrier hose it will leak out..

 

I have a dark interior and the AC performs OK, nothing like a modern car but I wanted to avoid the 6k quote I had to install a 964-style additional condenser in the left rear wheel well. Actually my other car is a 10 year old alfa 156 which doesn't do that much better!

 

I found a guy in campsie on the hychill site who charged the system up. 

 

If I had my time again Id probably do the hychill charge first with a stock receiver dryer replacement and then think about replacing the receiver dryer next; theres a fair bit of arguing in the US forums about whether the rennaire pro cooler makes a real difference and acts as an additional condenser like the manufacturer claims.

[Peter M]

Glom,

Thanks for posting your experience with Hychill.

As for a rear wheel well mounted condenser, Griffith/Kuehl do a kit for about $1000 that is all bolt in and involves no irreversible modifications. I think if you want a AC setup that works in heavy traffic, this sort of set up would have to be seriously considered.

Yes, I've noticed there are no fence sitters with the Pro Cooler!

Regards

Peter

[Coastr]

Hi Hunaudieres,

 

For another anecdotal story Im running hychill in my 81 SC, the basic anatomy of my setup is stock although I did replace the lines with barrier hoses in case I ever change over to r134 and have a rennaire pro cooler instead of the stock receiver/dryer which you will need to replace anyway. The only other change from 911 stock is I adapted a carrera pump and pump stand instead of the standard massive york pump, yours may already have it fitted if its a carrera.

 

Your system will have been setup for R12, so if you change it to r134 without changing the hoses to barrier hose it will leak out..

 

I have a dark interior and the AC performs OK, nothing like a modern car but I wanted to avoid the 6k quote I had to install a 964-style additional condenser in the left rear wheel well. Actually my other car is a 10 year old alfa 156 which doesn't do that much better!

 

I found a guy in campsie on the hychill site who charged the system up. 

 

If I had my time again Id probably do the hychill charge first with a stock receiver dryer replacement and then think about replacing the receiver dryer next; theres a fair bit of arguing in the US forums about whether the rennaire pro cooler makes a real difference and acts as an additional condenser like the manufacturer claims.

 

How much were you charged for the hychill fill?  I already have a replacement compressor and the rest of the system is stock.  I'm keen to see how this goes.  No plan to replace the hoses because it doesn't matter if the hychill leaks out given the low replacement cost.

 

As for the AC arguments - these descend into some serious flame wars - which is odd for something which is easily measured.

[Glom1098]

Cost was about 150 from memory. Actually today although it wasn't very warm here I managed to get a few ice flakes out of the ac after running it on coolest setting/low fan and then turning the fan up to max. So it gets cold enough to ice up the evaporator coils.

Hychill is flammable (it's derived from propane) and under pressure, but so is petrol. Like all combustibles it needs the right air mix though (mythbusters taught me that-Remember the scene in the first Bourne film when Matt Damon ripped a gas line out of the wall and then stuck a newspaper in the toaster-turns out it is impossible to recreate in real life.).