Amateur DIY Porsche 911 SC air conditioning installation

[classicretrofit]

A great thread here by PushinRice on Pelican detailing the installation of his system in a 911 SC. This was his first time working on his car! Amazing.

I have decided to document my install of the Classic Retrofit Electrocooler system into my 81 SC. A couple of disclaimers: I am not a mechanic. I'm a guy with 3 kids with a garage and a basic set of tools. I have no idea if my install will be successful, or how long it will take. I may be doing things the wrong way sometimes, so if anyone sees something that doesn't look right then please let me know. I will not be offended.

My SC was a factory AC car. When I bought it, I knew that the AC didn't work. I wasn't sure that I needed it, but after driving late last summer and fall I realized that it would be nice to have AC. I needed a bunch of work over the winter, so I had the independent that I use remove the factory AC components and lines. They also upgraded the alternator to a 90A unit as required. I ended up buying a new fan housing instead of having the stock one machined to fit the new alternator. I considered having the shop do the install, but the labor cost involved would have been very costly.

I read the directions a bunch of times and tried to get an idea of where everything goes, but it became apparent that I was just going to have to dig in and figure it out as I went.

Unfortunately, I can only work on the car an hour or two here or there when the kids are in bed or everyone is out of the house. I currently have about 8.5 hours into the install over 3 nights. I have never worked on the car before so I'm sure someone with experience will go much faster. I'm also doing a fair amount of cleaning as I go.

[classicretrofit]

First step was to remove the fuel vapor expansion tank and washer bottle tank. The hoses on the fuel vapor tank were crusty, so I ordered new hoses. The washer bottle required removal of the horseshoe bracket which was pretty self explanatory. The headlight also had to be removed which was not difficult. I would recommend emptying the fluid from the washer bottle reservoir. It was heavy even not full.

Once those items were out of the way, I was able to do a test fit of the replacement horseshoe bracket and condenser. The filter dryer is also designed to be connected to the new horseshow bracket. Its a tight fit, but the condenser and dryer fit in there.

With the condenser loosely in place, I spent some time trying to figure out where to run the hoses. The kit is flexible in this regard. As long as everything is in the right order, it doesn't seem to matter where the hoses are run. I messed around with a few options to see what seemed to work best. I decided that I would run both lines on the top of the wheel well. I removed the thick hose for the washer bottle filler from next to the gas filler to where the tank used to be. This gave plenty of room to rough the hoses in. I also decided to put the filter dryer in the original location, under the gas tank filler. To me it seemed that I could have more adjustment of the condenser without the dryer on the bracket. I also bent the bracket so that the sharp corner would not damage the condenser.

Then I removed the condenser to fit the hose connectors. This was not difficult, but I did need to make a decision about which direction to point the connector at the front of the car. I decided to have it point to the outside of the car. I measured approx. length of lines from condenser to filter dryer with a garden hose and used that to cut the line. I connected the hose from the condenser, over the wheel to the filter dryer without the Oetiker clamps. Then I took the remaining length of hose and did a rough routing into the smugglers box. I will be using the brackets from the stock AC to hold the new lines. I was able to get the lines over to under the smugglers box and found an existing hole to bring the hose through. I pulled most of the length through to the frunk, leaving some slack.

[classicretrofit]

Next I ran the hose from the front of the condenser, over the wheel and down past the filter dryer, under the car to the smugglers box. It was more difficult to run this line with the first line being in the way. I was able to use the same hole in the smugglers box with a bit of squeezing. I ran the whole length of line up into the frunk leaving some slack.

I did a good amount of cleaning. Dirt everywhere.

I took the condenser out again, and used the Oetiker clamp tool (which I had to buy beforehand) to do a full connect of the hoses/clamps to the condenser. There were videos online of how to properly do this. I spent some time trying to get the condenser to fit as far in as I could. Once I thought it was as far in as I could get it, I secured the bracket through the headlight. I did not have the bolt for the top, I don't think I misplaced it but its possible. I found another bolt that worked.

[classicretrofit]

With the under car hoses where I think I want them, it was time to work in the frunk. The instructions on how to remove the blower box were good, this was not a problem. Once this was out there was a plastic plenum that came out with some effort. I removed some other air hoses as instructed.

Instructions note things to do while blower is out that can't be accessed. I ran a sense wire from the rear window defroster. My blend valves did not fully shut so I adjusted those.

Then I tried to figure out where all the hoses are supposed to go. I think the instructions are a bit lacking here. A diagram similar to the hose routing would be helpful to visualize IMO.

Next is to place a T where the heater hose comes into the car from the drivers footwell. The instructions have pictures. My hose crumbled on touching. Had to pull back the carpet in the drivers footwell to access. I had a really hard time getting the T down to the hole where its supposed to sit. I have small hands but still couldn't get it down there with the blend valve and wire loom in the way. I ended up disconnecting and moving the blend valve to the side (wasted time adjusting these earlier). After moving some wires to the side I was able to get the T down there and connected the new hose from the footwell to the T. This was a pretty frustrating experience and I cut my hands a bunch, not fun.

With the lower hose connected to the T, I tried to figure out which should connect to the blend valve and which to another hose. It doesn't appear to be a possible fit without cutting the T, which the instructions state.

[classicretrofit]

I've fiddled with getting the T to fit to the blower and the footwell hose a little. I think I'm going to end up removing the blend valve completely, moving aside the wiring loom, and possibly removing the hood strut to make this work. I think I should be able to spend some time Saturday night on this. It's been good to give it a try and take some time to step back. Maybe I'm doing something wrong that has made it harder than it should be. I've trimmed the T at an angle on one port as instructions state and that has helped. I will post up the final configuration once it all fits.

CR: The 'T' pieces are probably the most awkward part of the install. For the sake of two screws underneath, moving the blend valves saves a lot of pain. Getting all those hoses in a tight space was a real challenge from a design perspective as well as catering for left and right hand drive.

[classicretrofit]

Finishing up, I did final connections on both sides of the dryer with Oetiker clamps and did final mounting of the dryer to the original mount. Then I secured lines to the car above the wheelwell, before and after the dryer, under the car, and under the car again before the hoses enter the smugglers box. I replaced the hoses on the vapor tank because mine were very old, then mounted the tank. Put the headlight back on, then the wheel and I was able to drive the car. It was all very straightforward.

 

[classicretrofit]

After a few more nights of trying to get the supplied "T" to fit without luck, I began to look for some alternatives that might work better for my application. I've seen pictures of some of the other installs and they prove that the T can work, but there's just so much in that area in my car that I couldn't get it to fit (blend valve, brake booster, wiring loom, hood strut). I found a Webasto 60mm-60mm-60mm "Y" that I thought might be worth a shot so I gave it a shot and ordered it.

I ran the idea by Jonny, and he said that he did not see any functional issues with using this fitting, but that I might have some clearance issues. With a plan of attack, I installed everything back into the car. To get everything to fit best, I ran the wiring on the outside of the hood strut. It went together relatively easily after this point. There was some minor rubbing on the hood strut which I was able to stop with some minor adjustments.

Installing the passenger side T was really easy, plenty of room. Took about 30 minutes. Using 2 1/2" Aircraft Spruce hose temporarily until more of the other hose arrives. The Aircraft Spruce hose is really nice to work with. Wonder if there is any benefit/downside to its use in this application. I think I prefer the aesthetics of the original hose personally.

 

[classicretrofit]

Tackling the electrical. First, I disconnected the battery. Then, I placed the compressor in the battery box and connected the 2 wiring looms to the compressor. From there I did a mock run of the wiring to get a sense of where everything will be going. There are really a limited number of connections that need to be made, each needing constant 12v or switched 12v. I had some spare powered connections in the smugglers from the uninstalled AC, and also some spare connections from cruise control which is not in use. I utilized those due to their proximity. Some may choose to run to the fusebox which I hope is fine either way. One long wire needs to go from the condenser fan in the wheelwell to the fusebox and one needs to go from the condenser fan to the relay on the compressor in the smugglers box. From there, 3 wires were run from the wiring looms to the fusebox for appropriate switched or constant connections. There were also connections to the cabin switch that was run from the cabin earlier. The orange wire is not connected yet, it will go to the orange on the blower box.

The remaining connections are the big positive connection from compressor to battery positive and the main ground connection. The big positive connection provided was way too short and it needed to be extended by many feet. At the same time I wired in the 80A fuse near the battery (which is nice and small by the way) and put it in a plastic enclosure to keep it from hitting anything.

For the negative, I chose to put the grounds on a single stud junction that I got from Amazon which is hidden behind the airbox. From that junction, I ran 6ga wire to the negative on the battery (actually on the distribution plate next to the battery).

With everything connected, I reconnected the battery and hoped nothing would catch on fire. Thankfully, no fire but I got to see the first sign of life from the system... a light blue glow from the push button in the cabin. I started the car and pushed the button and to my amazement the button immediately became a darker blue. Seeing this as a good sign, I went to the frunk and could hear the compressor running. I felt the ends of the 2 hoses coming off it and one was sucking air and one was blowing air. I believe that the wiring is in good shape and the compressor is working.

Next step will be to mount the blower, which I think I forgot to mention has the expansion block and 2 hoses coming off of it. Connect the ducting, connect the hoses to 2 hoses coming off the compressor and fill valves that I installed earlier. Then pressure test and if all goes well I should be able to have the system filled. Oh and reconnect the cables to the blend valves which I'm not looking forward to.

[classicretrofit]

The last of the install was pretty straightforward. The blower went back in pretty easily and the hoses were able to be connected with a small bit of fuss. I did remove the passenger side duct vent as it didn't appear to go anywhere. Like the instructions state, make sure the center vent stays in place as it can come undone easily. This vent seems to blow the hardest, so you want it as tight as possible.

For the drains, I blocked the passenger side hose and ran a tube from the drivers side of the blower down through the hose originally on the car. I made sure to test it by spraying lots of water in the box to make sure there were no leaks.

A mistake I did make was not hooking back up the bowden cable to the blend valve ahead of time. Now that its all back together I can't get to it. I'll have to put that as a punch list item. The front cables went back on easily. Still need to hook up the front cable, it seems a bit short but I should be able to make it work.

At this point, the vent ducting is tight. The electrical is done. The blower activates properly by the dash dial. The compressor will come on when the blue button in the cabin is pressed. I get heat at my feet with the levers between the seats open and the blower off. Obviously no cooling with no refrigerant, but making progress.

[classicretrofit]

Thought it would be a good time to pull vacuum to see if the system is holding. Connected the vacuum pump and it pulled to 30, but unfortunately it the low side loses vacuum within a few hours. So I have a significant leak somewhere. Will pressure test with Nitrogen to 150psi to see if I can hear any leaks.

[Dr jay]

Holy moly this is a great write-up! Thank you. I’m strongly considering doing the Classic Retrofit to my ‘78 chassis/ ‘89 turbo motor hot rod.  Living in Florida it’s a must! Can’t even drive the car in the summer more than 10 minutes without dying. 
this was a great read and gave me a little more confidence to do it! So thank you. 
my car (chassis) did not come with AC so I’d be starting fresh. I’ll let you know how it goes!

now 2-1/2 years later how’s the AC working?

cheers