Air Conditioning refurbishment for my 308

I've been a little remiss at posting lately, sorry. I'm still plugging along. Last weekend, I replaced all of my fuel lines (feed and vapor) along with securing my new ac lines and zip tying some heater hose around the new ac lines to prevent chaffing in a few places near the fuel tank brackets. After this, reinstalled the fuel tank and the back end is done. I am still awaiting one new "squirrel cage" fan for my new blower motor, and the radiator to come in from Nick. After these items arrive, it should only take about an hour to mount up (that means probably 3 hours....) and then charge the system! Unfortunately this coming weekend is out for me due to another commitment, so I probably won't be up and running again for another 2 weeks or so.

As long as your hoses aren't leaking or have bad fittings, those should be fine as you flushed them out. The big reason I changed mine out was to not make it look nasty with all kind of extra fittings on the back in order for the stock hoses to go to the different (Sanden-style) compressor.

From talking to other AC folks, it seems the biggest gains will be from putting in a new modern-style condenser and electric fans, along with a stronger blower motor. This is where I was losing the most efficiency due to the 35+ year old design. With the new condenser and fans, I should no longer have the trouble of NO AC while below 20mph! Sitting still in traffic with the sun baking through the front windscreen is not my idea of fun and this is the big problem I wanted to correct. That along with the inadequate volume of air. If you find yourself wishing your modification of compressors had "turned out better," I would look in the above mentioned direction...

Here's wishing you "cool driving!"

-J

 

It looks like a good idea to me. The only thing that you would have to be careful with is making sure that the hoses are protected from chaffing around any corners or rubbing on the tank retaining bands. Easily solved with some spare heater hose zip tied around on any "hot spots."

On mine, I made sure to leave enough slack where I could maneuver the compressor above the engine rather than on the floor. Either way, not dumping your a/c lines when you do a belt change is a plus in my book!

 

I agree completely! I thought they just took the picture with the liner out for display. I hope the liner isn't left out permanently. You definitely need that in....

 

I guess I have been gone for awhile! Only back on page 3 though.

Well, I received my new radiator from Nick's Forza and couldn't be happier! It looks fantastic! Notice how they fabricated some brackets an welded them to Nick's radiator. Very elegant and very secure! Since this condenser is a universal fit, my personal opinion is that would be a great option to provide on his radiators. (Just a thought Nick, if you're tuning in...)
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I also got to check fitment and it's perfect!
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Mounting the condenser and fans was pretty easy, too. I thought I would have problems with getting both the 12in and 11in fans in. The 12in is slighly thicker that the 11in and wouldn't fit down in the valence properly. I was able to offset it vertically, though, and it still has clearance for the bonnet to close.
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I did some ballpark bathroom scale weighing to see how much this project has saved:

OEM radiator/condenser/Lucas fans: 45 lbs.
Nicks Al radiator/Al condenser/Hayden fans: 22 lbs.

I also shed 7 lbs per corner when I changed out from Koni's to QA-1s : 28 lbs
And when the air pump went by the wayside....: 16 lbs
The spare usually stays at home too: 40 lbs

So that brings it down a total of 107#. Now if the driver could drop about 15 lbs, that would be awesome!

 

I also got a chance today to finish changing out my fuel lines/filters as well as prepping the electrical. Everything is wired and ready to go.

Steve Carr is coming by tomorrow to do the last few hose fittings and bring me one more new "squirrel cage" fan wheel for the blower motor.

Getting very close! I should be cruising in air conditioned comfort very soon! (Not a moment too soon, with the Houston heat!)

 

I can't really do that at this point. But I do know that the stock system holds 4.75gal coolant (according to the owners manual). After I fill it, I'll report back.

Most of the weight loss was in the radiator though. The new fans and condenser are lighter, but nearly the difference of the radiator.

 

OK! AC up and running! It's blowing cold, holding vacuum extremely well and cools well sitting still (didn't really do this too well before).

My middle fan speed is equivalent to my hi speed from the OEM blower fan. The Hi-speed fan does raise the head pressure (w/in acceptable levels), but is great for moving more air to initially cool down the cabin.

I rewired the fans to both come on when the ac comes on as this keeps the head pressure much lower and cools better. I'm not sure yet if I am going to make this change permanent as I have not had an opportunity to road test yet.

I still have a small fitment/trim issue to correct before I can test properly. One of my mounting brackets is catching slightly on the hood mount. It just needs a bit of filing and all will be good!

I have to leave for work now, but will get some pictures up in a few days. Everything looks nice and neat though with the new hoses and the charging ports are all conveniently located in the front by the dryer (definitely nice from a maintenance standpoint, of which I hope to be doing NONE for awhile on the AC!)

 

The new condenser will definitely lower the head pressure on your system. I need to take some temp measurements today to find out what I really have as far as output. I definitely have more flow with the new fans. At full blast, it does increase the temp a little bit (and increase head pressure at idle), but it does move more air to get rid of the heat in the cabin faster. I have a suspicion that I need to add a little more freon..... Still some bubbles visible in the dryer.

Also, I am going to set up my system to put both fans on when the ac switch is on (rather than just the right fan). I have been doing a little wire diagram reading and I believe I can jumper an input wire from the ac relay to the fan relays. This would be preferable as a butt-splice up front would unnecessarily increase current draw through one of the wires v. just sending the signal at the relays and have the system work as intended. Small difference, but from a strain on the system standpoint, is much more sound electrically (IMHO).

 

OK! No temps for you quantitative guys out there, but qualitatively, it is much colder. Even with 134! I promise to get you some numbers for comparison, but on a hot Houston day of 96 at the high and lots of humidity, the AC kept up fine. Also my temps with Nick's new Aluminum radiator was running no hotter than 185deg. Now it was overcast, so I didn't have the greenhouse going in the cockpit, but still very cool inside. I use the high speed to take the heat out of the cabin and move a lot of air at first then transition to the middle speed.

Also, as a temporary solution to increase volume further, I took the plenum off between the outlet hose on the evaporator and the vents. It blows a ton of air underneath the dash and up the console. Also, there is residual air that does direct itself out the vents, just due to positioning. I could just be imagining it though, and it's just psychological to play with the vents!
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Also, I finally figured out the relay issue: To remind everyone, I wanted to change the logic so I have both rt and left fans coming on with either the AC on or the thermostat reaching it's trigger point. This will allow to keep lower head pressure in the ac system and make for cooler air, especially at idle in traffic!

At first I thought to just run a butt-splice between the two fans, but that was not really a good idea, due to wire gages/all amps running through one wire v. two and having what amounts to both fans on one fuse and relay.

Next idea was to jumper the "trigger" wire on the relay from the AC relay to the fan relay. (The fans already run a jumper between them, and that is triggered from the radiator thermostat switch grounding when it reaches temperature). The only problem is that the trigger on the fan relays is looking for a ground and runs 12v potential on both sides of the relay poles. When it is jumpered to the AC relay, because of the way that relay is connected to both the AC switch and connects through HI/Lo pressure switches to engage the clutch at the compressor, well this now provides the ground (through the compressor) right from the get go. Plus it blew out my fuse just in case there was any doubt! (it got pretty hot, pretty fast!)

SOOOOOO, My solution was to go buy a 12v DC SPST (single pole-single throw) 30 amp relay from Radio Shack. I then connected the AC jumper and a ground to the two poles as a trigger, then the other switch side, I ran to the Fan Relays and ground. Works like a champ! The fans use their own relays and fuses. No additional power to the relay board. I eliminate the AC fan relay and add the SPST relay on the lower right corner of the board (see picture). The original AC fan relay (usually occupying the upper middle spot) is now on the lower left, as a spare.

Thanks to Paul Bennett for his AWESOME color wiring diagrams. It made the job so much easier! ($20 well spent in my book!)
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Actually the new system is holding less coolant. Or at least appears to be. I am pretty sure there wasn't anything left in the lines, but there may have been residual coolant left in the block. When I drained the system, the rear of the car was jacked up with the front still on the ground and both front coolant lines disconnected. Most of the coolant should have drained out. Either way, I only had to add 3.5 gallons into the system. This leads me to believe that the weight lost from the Al radiator is not gained back from additional coolant.

 

I finally have some performance data on my project. This past weekend, I got together with Steve Carr and we checked on the system to make sure we had the proper amount of R-134 .

There were still some bubbles showing in the window of the dryer, so we thought maybe the system was undercharged. Not so. We added some coolant only to find that when the engine was revved over 3000 rpm, the head pressure was shooting up to 310 psi, causing the hi-pressure switch to cycle.

We vented it back down so the maximum head pressure we were seeing was 250 psi with engine rpm @ 3500 and about 210 pounds at idle.

We also noted that the temps were coming down as we took more 134 out. We kept taking coolant out until we fine tuned our coldest temperature: 41deg at the vents. Outside temp was in the low 90s and the car was at idle in the shade. Humidity, well, it's Houston, so it was definitely Humid. How Humid? Not sure. Not quite Puerto Rico humid, but pretty darn humid.

So there you have it: Air conditioning re-furbished, blowing 41 degrees at the vent, with R-134 and blower motor that definitely gives some extra flow to cool the cabin quickly.

I am currently working on a vent solution to give me a small "eyeball" vent just below and to the left of the steering column. I have something rigged now for testing: some aircraft SCAT tubing off of the main vent. So far it works great! I will be getting some different size tubing soon for a more permanent and "smoother look".

I'll post some pictures of the mod when I get home.

Cheers!