Installing air con in air cooled 911

I have decided to chronicle my DIY air conditioning install in my 40 year old 911sc .  So far I have installed the mounting bracket and condenser. It is an original bracket I got for $150 from a Porsche mechanic.  It was very difficult to install and I had to resort to a hammer leaving some divots in the steel.  These will be hidden by another part that sits on top that I still have to get. I was able to install the condenser in the wale tail.  It has no fan but my theory is the engine fan will draw enough air through.  Condenser is a universal 600x300 I got off EBay for $100. After much research I found the Sanden SD5H14 was the best compressor for the car which is sold in many after market kits.  It is used in heaps of different cars and I got a used one from the wreckers for $80. I am planning to use the original fresh air vents which had been disconnected.  I used some plumbing couplings and flex hose to connect them to pipes that go either side to the front trunk.  This was a little tricky because the vents were all seized but I got them working, sans the closing flaps that I will never use anyway.  I had to buy an original replacement centre vent duct which cost $50 on EBay.  Plumbing bits were about $30. Total cost so far is $410 Labour has been about 10 hours. Lots more to do yet. But it not summer for a while.

Any tips from someone who has done it are welcome too

Hi Nevdog A couple of comments/tips from someone who has been down the same route. When I bought my car like yours it was an SC that had previously had AC but was missing quite a few bits and pieces. Maybe you can tell us what bits you do have to see what else you may need. I can see you have the original ac bracket-do you also have the evaporator box/fan assembly in thefront passenger footwell and the front condensor/fan assembly? How about the fan and temp controls? With regard to the compressor and bracket there are a couple of options. One of the things that will limit the use of existing components is whether they have O ring or flange fittings (flange fittings were used up until the 3.2 carrera from memory). Not a deal breaker as you can have custom hoses made with a mix of flange and o rings. You may find the Sanden Sd5h14 a bit too big-from memory it is the newer version of the Sanden 508. The current guides suggest to use either a Sanden sd507 (or one of the cheaper copies-there are chrome plated ones on ebay for less than 200 dollars) or an SD5h11 with the right fittings. If you do want to go with the one you have I would suggest trial fitting it with the belt lined up to see if its going to fit-you may need to grind down the alloy 'shelf' on the rearward intake runner on the right side. Griffith air do sell a bracket that bolts onto the bracket you have to fit one of the sanden style compressors ( https://griffiths.com/product/porsche-911-kuehl-kwick-507-ac-comperssor-adapter-set/ ). This can be used with any of the sanden or sanden copies. The griffiths site has a lot of useful info. Another option that I know will fit is to use a carrera 3.2 compressor and the alloy stand that it fits. This has o ring fittings and needs a bit of modification to the tinwork around the back of the engine but the stand is lighter than the one you have. Griffith recommends this compressor for the 3.2 and later cars-they are meant to be quieter. My SC has exactly this combo-it fitted with grinding back of the intake runner as mentioned. Let us know how you get on. My system uses standard porsche bits with a 'procooler' in the left front footwell and the 3.2 compressor. I filled the system with Hychill-an LPG based refrigerant that is more efficient than R134. The car stays cool on very hot days unless you park it in the sun and sit in traffic without getting much airflow over the front and rear condensors. Ive just fitted carbs to my car-and unfortunately the 3.2 compressor no longer fits. I am looking at going back to the older compressor bracket with one of the sanden options as mentioned above. So I may have a compressor and bracket for sale shortly that may work for you if the existing bits you have dont. Lukas

Why are you going back to the old compressor bracket? I am starting to plan out AC reinstall - thinking about fitting thermo fans to the rear condenser - heat soak on a hot Aussie summer day is massive and I don’t think the engine fan pulls enough fresh air in through the condenser. It seems either that or fit a rear wheel well condenser with fans - but it is so much surface area when 964s and later, as well as the  electric Ac kit use a very small condenser in comparison. I used hychill in my first AC reanimation and it works fine but I wonder on resale (prob selling that car soonish) whether folks might get worried about that.  Hard to find Ac techs that will support it, and not everyone is going to do their own Ac service work.  If you’re keeping the car it’s fine but buying one Porsche always leads to buying another and eventually we sell one we thought we never would.  But it is better than r134. I bought Rob Siegels book on vintage AC DIY - it’s an excellent reference despite being bmw centric.  It spends a lot of pages on various fittings, theory and application.  Prob worth getting when working through a restoration where you’re using a combination of parts and not all oem.

This is what I had when I upgraded the AC system, note the bracket. So I modified it to suit the new compressor.

This is the "old" system in a 930, before I upgraded, with the front and rear condensors.  I thought the 911 had only the rear engine lid condensor, but I could be wrong.  Maybe it's model dependant. The front condenser has a fan from factory. and the shiny new "kit" and I added a fan to the rear condensor

Is it a Griffiths kit? The early 930s with Ac had a ducted condenser that fed directly from the engine fan.  Intercooled cara has to drop that. 911s with factory air from about 77 have a front condenser with fan.

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It’s a Retro Air kit.  I think Rock Browning has sold the business since.

Yes, now part of https://www.classicautoair.com/

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No wonder the original system is crap. Look how long those hoses are!!!! Not to mention the heat soak as mentioned.

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Yep, the whole system is just an add on and they never improved it.

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Hi, I am using  a universal evaporator which is much more efficient than original.   It sits it the trunk.  I got some original control knobs that I attached . Thanks for the advice.

Nev, How are you going to recycle the cabin air back to the evaporator? Or are you just going to supply fresh air to the evaporator by driving with the bonnet propped a little open? 😊 Like what you are doing.  My only advice is make sure you have plenty of vent area.  With the pre' 86 vent cars you really need some under dash vents to get adequate cold volume for comfort.

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I don’t know yet, I am just going to pump some air in, I’ll tell u how it goes. This weekend I fitted the evaporator/head unit in the front trunk.  It has 4 outlets. I blocked one off and the other three were fitted to three fresh air vents in the dash (left, centre & right). I was able to use flexible ducting that fitted around the existing heater/blower system.  I used some plumbing couplings to attach to rear of vents.  The duct is all concealed by a panel I made from aluminium covered with felt to match trunk liner. The fan/evaporator is screwed to floor of the  trunk, forward of the fabricated panel.  It takes up a small amount of room.  The pipe work will come through the smugglers box. I also got a bracket engineered to mount the compressor.  The compressor is mounted.  I used a 1125 v belt. I made up a loom and connected the controls to an original 911 centre console panel I was given including knobs. Total cost this week is $350 including. -concealing panel. $20 -compressor mount. $100 -evaporator unit. $170 -ducting $60 About 10hrs labour this week Total overall cost is $760 Total labour 29hrs

Well done! Can you post some pictures of the compressor bracket? If you have a smugglers box (I presume an LHD conversion) can you create an air path between the cabin and the front hood? As Peter mentioned you ideally want to recirculate cooled cabin air back through the evaporator. It would mean that you may end up cooling under your trunk as well though! Lukas

How did this end up?