Dual 993 a/c condenser system

[Canada Kev]

Originally Posted by Pazuzu

I'm working off the assumption that we all know that the giant windshield washer bottle needs to GO for this to work. Once that is moved out and replaced or deleted, then there is all sorts of room up front, and that area has lots of airflow from around and under the bumper.`

Giant washer bottle? What are you talking about? It can barely even hold an entire keg of beer!

[Pazuzu]

Originally Posted by Canada Kev

Giant washer bottle? What are you talking about? It can barely even hold an entire keg of beer!

Dude...the keg of beer goes in the giant back seats. If you're carrying and drinking your beer through the washer system you're doing it wrong...

Rear seat keg with NACA ducting to a helmet is how us professionals do it.

[Pazuzu]

Time for an update, since I finally got to put a bit of effort into this...

Started mounting the 2 condensers. Rear was pretty easy, the mounting design is well established from others (like I said, shoulders of giants...).

Rear wheelwell condenser:


Rear wheel clearance (I set my condenser sideways, which makes it shorter but deeper):


Front wheelwell horsecollar mount (need to connect to this now):


Enough work for today, time for a break

[Rawknees'Turbo]

^^^

Good progress there, Mike! I bet you'll have a big smile on your face once you get the system operational - really heating up here in Norf TexAss (grossly humid, too), and probably even worse down thar in Houston!

PS - maybe you've mentioned this previously, butt what was your reason for placing the rear condenser behind the wheel (as opposed to in the space in front of it)? Not passing judgement, just wondering . . .

[Pato911]

Nice work. I finally got mine fully installed and charged. For the first time, I have cold air out of the vents. Just in time for summer.

[robcf]

Im interested to see how your front mount compares to the patrick motorsport version. Are you going to use more than one attachment point to the condensor?

1973 911 RS Pro Touring | 993 3.6L DME | G50 SBH By Patrick Motorsports Porsche & Mid Engine Performance Specialists

[Pazuzu]

Originally Posted by Rawknees'Turbo

PS - maybe you've mentioned this previously, butt what was your reason for placing the rear condenser behind the wheel (as opposed to in the space in front of it)? Not passing judgement, just wondering . . .

Honestly, I'm not sure how well it will fit. The torsion bar assembly would make it pretty close. I think that the Zim's unit as well as the Duel Keuhl unit is a smaller, proprietary condenser that fits in there better. I know the Zim's one actually uses the torsion bar cover as the primary mount, it has a U-bolt that goes around it and the condenser is locked in place. I thought about doing that, but the one time that you want to do any t-bar work and have deal with a condenser that barely fits there to begin with? No way, that would make it too much work.

Originally Posted by robcf

Im interested to see how your front mount compares to the patrick motorsport version. Are you going to use more than one attachment point to the condensor?

It's hard to tell how they did the final mounting, but mine will be hung from that horsecollar, which is mounted in 3 locations and designed to carry, what, 20-ish pounds of water all day long? I think I will tie the condenser to the horsecollar, then the horsecollar to the body in those 3 locations, and let the whole thing hang there.
They have theirs turned 90 degrees from mine, I know that is how the factory did it (with the primary lines running vertically), but I was trying to avoid that, especially with the second condenser. I'm not sure how much system pressure there is by that point to make sure that everything is flowing well against gravity. I will have to run a #6 fitting on the outlet of the first condenser and a #8 fitting on the inlet of the second, I will run #8 hose for that, I just need to pick a proper #6-#8 fitting. I hope the short section of #6 fitting (maybe 1 inch of steel line in the fitting itself) doesn't adversely affect the pressure there.

[Jonny H]

Hi Mike and Pato,

Am following your front install with interest as I am doing the same on my SC. Annoyingly, the Boxster PFC condenser is just an inch and a half too long to fit in the front. Shame as it weighs about half as much. You might get one in the rear fender though and they are half the cost of the 964 item.

Got any ideas on stone guards?

[Pato911]

I looked at the Boxster and a Honda Civic condenser and either the dimensions weren't right or they had different connections. As I mentioned, I finally got my install completed. This is not my thread but I thought that combining results and information would be better than starting another.

Photos are worth a 1000 words:


The space available with the windshield washer reservoir removed/ relocated. The fender-valance bracket takes up too much room. Remove as I did or replace as the OP did.


I had to cut the fog light bracket on my valance to get the additional space required and keep the condinser oriented with the loops horizontal.


First trial fit with cardboard mockups of shrouds.


My attempt to re-use the hose that connected the compressor to the rear condenser. There was too much length to tuck in and it hit the tire.


Final install with a new, custom hose. Fits perfectly with the top supported by the headlight bucket and the bottom supported on the support/ shroud that bolts to the valance with the bottom sploiler strip. I consider extending the support over to the A-arm front mount but it all seems pretty secure.

[Pato911]

In addition to the front fender condenser, I also replaced my resistor pack blower speed control with a PWM board from ebay.

PWM Controller


My sketch and some notes.


I cleaned up the routing and tucked the wires into some tubing for cosmetics and protection.

Originally, I had planned to mount the control knobs in the original box bolted to the ashtray support but the new thermostat which came with my new serpentine cevaporator didn't fit in the box. I fabbed a quick one up with ABS sheet and PVC glue. No picture as its funtion/ form ratio is too high for the public.

Everything works perfectly and I have full speed control over the blower fan for <$30.

[Pazuzu]

Got the chance this weekend to finish mounting the rear condenser for sure, and the front is 90% complete. I might want to add a single locator strap still, we'll see...

I was able to inventory the hoses I had from before, and put together a list of fittings needed, got that order in and will see them before this weekend. If I get some time during this week I will start to measure hoses and cut the old fittings off. Still need to do some wiring (front fan will take the existing front condenser blower power, rear will tap off of my relay box in the back).
Make some stone guards, mount the lines, clean everything inside and out, and hope to have working A/C by July 4th!

[Pazuzu]

Both condensers mounted. both fans wired. All hoses completed and mounted.
Dryer opened and connected, system evacuated then backflushed to 85ish psi with R134...thrice. found a poor crimp the first time, but all is good now.

I have the system under static pressure with refrigerant to check integrity. I SOOOO wanted to just finish this, but i have no compressor oil and the system was dry, so I have to wait. Once it arrives, I'll evacuate again, put some oil in, then do a final fill.

It will be so nice...

[Pazuzu]

So...
On 6/19, I filled to 85 psi static charge to keep the system dry. There was no compressor oil, so I couldn't go any further.

Ob 6/25, I was able to get back to work. The system had dropped to 15psi but at least it wasn't zero, so there wasn't any moisture entrance, and I wouldn't have to mess with the dryer. I know the only way to find the leak would be to get some pressure on it.

"Recovered" the refrigerant that was in there, opened the compressor and put 5 ounce of pag 100 oil. closed it up and immediately pulled the system down for 2 hours.
Backfilled to 90psi static pressure (OAT about 93 degrees). Started a full fill.
at 30 total ounces, I was at 30/210 with a vent differential of 17 degrees (80/63). Not very good
Went to 40 total ounces, above 30 the low side went from 30-34, the high side went from 210 to 240, sometimes 250. Raw vent temp never went below 58 degrees, even as the interior temp dropped below 80.
Car was sitting in the sun for all of this, lots of radiant heat being soaked up.

Drove out to a BBQ, highway speeds for 30 minutes, car was, eh, acceptable. By the time the BBQ ended several hours later, I had no cooling.

[Pazuzu]

6/26
Checked the static pressure, there was some (25ish pounds).
Evacuated the system, charged back up. Went straight to 25 ounces before I started taking measurements.
Car was NOT heat soaked, it was in the shade after being in the garage, so it had a good stable temp right around 90 degrees.
25 ounces gave me 30-31 low, 205-210 high. High fan doors closed, internal temp was 88 degrees, with 60 degree vent temps. Evaporator had a core temp of 49 degrees. Added 5 more ounces, went to a 47 degree core, 32/210, 60 degree vent.

Drove to store, was happy! Nice temps.
Car sat in direct sunlight, 95 degree OAT on a hot parking lot, for 45 minutes.
Got back to car, and could see and hear the leak! Weeeee! Back crimp on one fitting.

Drove home with 70 degree vent temps, and got to work on the crimp. Fortunately, it was on a SPLICE so that I was able to get the hose pulled away from the car enough to crimp in place, with pressure in the lines. Gave it the beans, leak stopped.

Rather than evacuate, I decided to fill based on evaporator core temp. I didn't know how much was still in the car, so I don't know what the final fill was.

HOT car, very heat soaked. Final numbers 31/210, evap core temp 47 degrees at highest fan setting. When fan was set to low, core temp dropped to 38 degrees, maybe 37.

Drove car at highway speeds for 45 minutes, high fan speed, car was super hot and the highways was a 18 lane ribbon of burning radiant heat. Vent temp hovered around 58, temp at my head dropped to 79 eventually.

Seemed eh at best, but it's hard to tell when the car is that hot.

[Pazuzu]

6/27 (today)

Car was in garage all night, very stable temps. 88 degrees in and out.
Pull out of garage, vent on high, neighborhood speeds.

3 minutes, I had 55 degree vent temps, which is a 33 degree delta. 20 minutes into surface street trip, the interior air temp was 70 degrees.
If I set the fan to low, I got vent temps around 40 degrees.

Pressure held, and car will produce 40 degree vent temps with low fan speed, as long as it's not completely heat soaked. Remember, when I say heat soaked, here in Southern Texas, after 30 minutes sitting in the sun, the interior surfaces are 140-150 degrees. Even if you open the windows and vent the air, the actual car interior keeps things very hot. I had a dash temp (not driving into the sun!) of 109 degrees. That was the heat coming through the window, from the road surface. So, vent temps of 55 degrees when the dash just an inch above it is 109 seems pretty good!

[Pazuzu]

OK, did 2 final things which have made a difference.

I didn't know how much charge I actually had, so, I evacuated and ran 23 ounces in. At that point, I expected that I could add 2 ounces at a time over the next few weeks, and have an accurate measurement. I haven't added any in over a week, still at 23 ounces total.

Also, found out that the front condenser fan had an intermittent connection at the fuse, so it was either running at under 12 volts, or maybe was cutting in and out quickly all of the time. Fixed that. I learned that when that fuse blows, my vent temps skyrocket to 75ish degrees

Now, I have 35-40 degree delta at high fan speed all the time. I've been turning the temp down to cycle the compressor on the drive to work in the morning (88ish degree ambient). The actual interior temp drops by 10 degrees in the 20 minute drive to work. Vent hit 53 degrees at high fan speed, within 10 minutes, from an interior temp of 89 degrees.

53 degree vent temps is surprisingly cold...like, make my hand cramp while sitting on the shifter cold.

I guess 23 ounces is good enough.

[Pazuzu]

So, some updates and some info...

Sometime over the winter, the front condenser started slipping down and eventually wore a hole in the serpentine freon line, which meant lost of freon. So sad
Also, I redid a bunch of wiring (http://forums.pelicanparts.com/porsche-911-technical-forum/923794-new-front-fuse-relay-panel-using-busbar.html) and new that I wanted to update the a/c wiring, but hadn't decided at that point what to do.
So, the past few weekends I tackled this. Replaced the condenser and used a much sturdier mount (took a cue from Pato911 and ran a bar laterally between the condenser mount and the bolt holding the front a-arm mount). The system is now incredibly sturdy, and won't be a problem anymore.

So, since my wiring updates were driven by putting all of the amperage into relays and bussbars, I continued that design with the A/C. A fuse powered [acc/run] feeds the fan switch. The RED/WHT wire from the fan switch (the "full speed" wire) now feeds the trigger on a relay that runs the evaporator fan directly. The resistor pack is no longer in the system.
The fan switch also feeds the temp switch, where the GRN wire then feeds 2 relays. One in front which supplies the front condenser fan, and one in the engine bay that runs the rear fan and the compressor clutch.
So, 3 relays, 3 fans, and a fan switch that now only sees 2-3 amps, instead of 13-15 like before (we all know those switches are just a moment away from starting a fire...).

The good: Better condenser mount, much better wiring, and a nice cold charge of freon, system shuts down when starting car since the fan switch is only triggered acc/run, no need to do that silly "feed voltage from the ignition switch to pin 85 of a relay" stuff.

The bad: The evaporator motor running directly from battery power with a relay is SO FREAKING STRONG NOW. Holy hell is that a strong fan when it's not hobbled by the fan switch and resistor pack. So, that's not really *bad*, but what is *bad* is my design precludes fan speeds, it's all on all the time. I'm not sure what to do about that. But, my hair blows fetchingly while driving like you see in other, modern cars.

Anyone want to design a wiring system for me that can use the fan switch levels to trigger some sort of fan control that can vary the voltage going INTO my fan relay? I need the switch to give a full trigger signal no matter what to pin 85, but I need variable voltage to pin 30 so I can feed variable voltage to the fan on pin 87.