Second Condenser for Classic Retrofit Electric AC

Classic Retrofit's electric air conditioning system has become the number one option for Porsche 911 enthusiasts keen to improve the usability of their cars. While many clients report huge improvements in overall comfort, even in fairly average climates, many of our customers use their air-cooled 911s in climates where summer temperatures and usual humidity are anything but average.

Good product design includes a certain amount of redundancy and over-engineering, so we've been looking at ways to further improve the performance of our air-conditioning systems for those living in extreme climates. Enter the second air-conditioning condenser.

Since the start of 2020, we've been testing and developing a quiet revolution in 911 cooling system and HVAC design. On our 'test mule' 1982 911 SC, this involved the relocation of the oil cooler from its standard position under the right front wing to a new location, with a brand new modern-tech cooler and high efficiency fan installation, mounted behind the left rear wheel.

Note that some 911s can run both an oil cooler and a second condenser together - this is just how we are tackling the development for now. Relocating and optimising the original oil cooler is part of a multi-layered product plan that incorporates our designs for the latest evolution of the electric heating project, but more of that later.

For the purposes of achieving ultimate 911 air conditioning, relocating the oil cooler left a big empty space for a second A/C condenser, which we have since fitted.

While Jonny's initial testing has been extremely interesting on the oil cooler side, the upgrade has truly revolutionised the results for our electric A/C system, with the air conditioning running so cold (-1.5°C at the vents) that we had to implement evaporator anti-freeze protection in the firmware.

Keen to see how the system performed in a more extreme climate than the UK could offer, we sent a prototype kit to our friend in Florida, Chris Bolton. Jonny and Chris met at Daytona last year. Chris runs several hot rods, one being a ratty 1975 911 S fitted with a 3.6 and many performance improvements. The pair had a good discussion on potential A/C upgrades.

Florida weather is a real test for air conditioning, with ambient temperatures into the mid to high 30s Celsius and humidity of 65%. Chris' initial testing of his upgraded installation with second condenser is a real eye-opener.

"Last weekend, I added a second condenser to the passenger front fender to help the system face the humidity in my Florida climate. Running on one condenser last summer, the system was very good. But, as the photo shows, the second condenser has greatly improved the electric A/C system's performance; particularly its ability to quickly cool the car off after it's been heat soaked (sitting in the sun in a parking lot for hours).

"These numbers should blow (the minds of) those in the know," says Chris. "To translate, in this pic you see a 96°F (36C) ambient outside air temperature with 65% humidity, 26.4°F (-3.1°C) evaporator temperature, and a 40.7°F (4.8°C) centre vent temperature. That's with all of the vents open and the blower running full power.

"Continued testing and development shows that the Classic Retrofit setup is by far the best system for an old 911. If you do not live in a very hot and very humid climate, get the one-condenser set up. For those of us in the tropics, the two-condenser system is absolutely stunning.

"I am not sure you can get better A/C for these cars, especially when you consider that this photo was taken with all the vents open, and with the fan on full power. And remember I think the Classic Retrofit blowers probably blows slightly more air on #2 then anyone else’s blowers blow at full power. I know as my ‘89 Carrera has a trick factory style system in it, and this blows that away."

"I can't thank Chris enough for his amazing help in supporting Electrocooler," says Jonny. "It's no surprise that the UK climate does not always lend itself to testing: we simply don't get the hot and humid conditions experienced in Florida.

"Chris and I met up at Daytona last November (pic above with Jonny just off the red-eye flight) and hatched a plan to trial the second condenser in his '75 hot rod this summer. His initial results are pretty amazing. Chris has also gone the extra mile to record logging data from our ECU and send it to us for analysis: another great example of the air-cooled community pulling together."

Note that the second condenser should be mounted in a separate location: sandwiching over the existing condenser is not as effective due to airflow and heat dissipation. Chris's car has a nose-mounted oil cooler, so both front arches were free.

The second A/C condenser is now available for purchase - kits are ready to be shipped to customers in all 911 danger zones from Texas to Thailand! Contact us with any questions.