Air Conditioning refurbishment for my 308

Well, the heat is starting to set in here in Houston. It is supposed to be 92 all week with high humidity (is there any other kind in Houston?).

When I got home from overseas this past February, my first order of business (on the car that is) was to take the parts I had been accumulating at home and restore/upgrade my suspension. I did the QA-1 shocks and Eibach springs, new bushings all the way around (ala Birdman's abbreviated method of cutting the old ones off and taking the "guts" from the new energy suspension bushing to replace the old.)

Now it is time to address the a/c!

I have a 79 with a york/aspera compressor and R-12. When it is charged, it blows very cold air. Unfortunately, it doesn't stay charged for more than 6-8 months. There is definitely some leaking going on.

Some other problems I have had even when it is working, is that at a stop, there is usually not sufficient air flow to cool the freon in the condenser. Once you start rolling, it then works just fine. Obviously, I am losing efficiency in the condenser and the fans.

Problem number two is that when you are driving the car for any length of time (over 45 minutes) the blower motor starts to lose efficiency. I think the windings on the 31 year old blower motor are heating up and therefore the motor slows down. PLUS, as I am sure everyone who drives one of these car can attest to, the volume of air that the blower motor puts out is not NEARLY adequate enough to cool the cabin.

After doing a leak check of the system, I have found that I am leaking freon from three locations! Around the pump shaft, from the evaporator section and from some of the hose fitting up front. (That's pretty much everywhere right?)

So here we go for the complete ac redo on the car....

 

I figured while I was going thru the a/c, might as well go thru the cooling system as well.

After sending the radiator out, I found out that it's in need of a re-core. Rather then just getting the original back (with the same original weight), might as well upgrade the cooling as well.... I just place an order for one of Nick's Forza's aluminum radiators. It should be here in about 3-4 weeks.

Once it gets here, I will be mounting a new flat-tube, double-pass 12 x 24 " condenser to the front of the radiator, cooled by 2 Hayden-style electric fans. That should definitely help with some of the cooling efficiency problems. The new fans push considerably more air than the original Lucas motors.

Right now, I am working on some brackets to mount the condenser to the radiator...
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Out with the old York compressor. And replacing the AC hoses, front to back. The new hoses will have both charging ports located at the front, near the dryer. Should make it a bit easier to service.

I am also working on setting up the brackets to make it a little easier to remove the compressor during belt changes.
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there has been an ongoing project by rob on upgrading the system. doing a search should bring you a wealth of invaluable info. good luck.

 

Thanks. I have read through it numerous times. Development of a finished "kit" seems to have stalled however. His working model seems like it is awesome. I just thought I would start working it from a "poor man's perspective", i.e. not redesigning everything, but trying to use "off the shelf" type modifications to build a better performing system, without a mind toward originality, but more toward cost effectiveness. If I hadn't had to replace the radiator, I would be in for less that $1k. We'll see how far down the rabbit hole I go....

 

Where did you get the new condenser?

 

I have been working with Steve Carr, of Carr Auto Parts in Houston. He specializes in AC components. I was going to just go with the 20 x 12", but we were able to tweak the larger 24 x 12" condenser in there. The fans are from JPI (pretty much the same as Hayden) and will mount directly to the condenser, also purchased from Carr. I am mounting a 12" fan on the right and an 11" on the left. The condenser was about $100 and each fan was around $40. I'm also going with the Sanden type compressor. It has more cylinders than the York, is lighter and has better performance at idle speeds. The combination of the compressor, new more efficient condenser and these MONSTER fans on the front should eliminate my problem of no A/C at idle in traffic on hot Houston summer days!
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As I mentioned in our PM exchange, be sure to set up the fans so they both come on at idle when the AC is turned on. With the OEM set up on, only one fan comes on.

Also, are you running a rubber AC hose all the way to the bottom side of the new condenser? The old condensor has a AL tubing running up to the the top of the condensor and over the radiotor, then a bracket connection at the top to hold everything together with a AN fitting to hook up the lines. It looks like you've got a hole at the top and one at the bottom.

 

Think Steve Carr will make me one too?

 

Sean,
Thanks for the reminder. My only concern with going with both fans on is the extra current draw. If one fan is sufficient to keep everything running smoothly and the thermostat switch doesn't reach its trigger point (185-190, I think IIRC), why have the extra current draw on the system? But then, these fans draw less current, so maybe it won't be a factor... Right now, I plan on seeing how it performs with the one wired to the AC switch. I can always switch it over to turn both.

I think I need to go out and put an ammeter on the two different fans and see what they are drawing. Then I can make a final decision....

 

I am sure he would be more than happy to send you the parts! I am doing most of the assembling myself. I'm also working with Nick (Forza) to see if we can tweak the mounting brackets on his radiator to allow for the newer condenser.

 

Sean,
To answer your question IRT the connections, Steve and I discussed making an aluminum tube that runs up the side from the bottom and goes across the top portion of the radiator just like the original. I think taking the rubber hose up from the bottom will be to restrictive in the amount of space we have to work with. To get the 12 x 24 condenser in there is going to a tight squeeze. We had to trim the bracket off of the one side of the condenser to make as much room as possible for the connections. If you look closely on the above picture you can see that there are mounting brackets only on three sides of the condenser. It used to have them all the way around.

 

these certainly are the first steps but to get at the heart of the problem you'll need to address the interior. the evaporator and fan are the weak links. if the evap coil freezes up no air will circulate or you'll have the wet foot problem. heat intrusion itself needs to be remedied too. good luck. we all are hoping someone can solve this problem.

 

You are correct. I am having the evaporator checked out this week for any problems. After some debating, I have elected to go with R-134 v. R-12 for my refrigerant. We'll see how this does to remedy any freezing issues. Also, the volume of air is a huge problem. My old blower motor and fans are not that great. I think being a 31 year old electric motor is part of the problem. The motor has definitely lost efficiency and loses speed after it has been running for 45-60 minutes (as noted in my first post on this thread). I have a new 3 speed motor that turns faster and blows at least 30% harder than my old fan. In fact the middle speed on the new fan feels like full blast on the old one. This will be my "plan A" to increase flow.

"Plan B" will involve remolding the evaporator box and adding an additional blower motor in the footwell. There is some unused real estate I can use forward of the ECU panel in the passenger footwell.
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I got the new compressor mounted today. I just need to measure around the pulleys now to get a new fan belt.
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On a Porsche site I was reading about upgrading AC on old 911s. One thing they mentioned is that the old hoses get porous along their whole length, meaning that you have 20 feet of leaky hose. I see you have the gas tank out. Are you pulling new hoses through the length of the car as well?

 

Yes. Hoses are coming out and being replaced front to back. After getting the right gas tank out, I was able to unthread the lines from the frame and have a reasonably straight pull from the back. I also threaded the two hoses from the front and down into the right front wheel well (after removing the rear panel from the right front wheel well). The hoses seem to take two turns toward the back, very close to one another. I put some vaseline on the hoses at the back and front and they slide much easier. Still takes a good bit of force.

I have two lengths of hose, 20 feet each. I am going to put a temporary fitting on the hoses and connect them up front. Then I will pull them through from the rear. I have to wait until this coming weekend, when I get the fittings. In the meantime, here are some pictures of the hoses where they go into the frame in the front. You can see where the feed in from the back in post #3.
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See the posts by "twentyover" he is in HVAC design for a Detroit OEM.
http://www.pro-touring.com/forum/showthread.php?t=54044

This quote below,

 

This is a great thread. I'm doing the same compressor swap on my 365GT4. Please post the old and new belt sizes it should help me figure out what size I'm going to have to change to.
Looking at the new compressor and bracket I would guess it will require a slightly longer belt.

 

This is a good thread .

All great ideas except - based on my first hand experience - the 134 idea.

I swapped in two cars and was so upset that I paid whatever to re-convert back to 12. Now things are cold again.

 

Actually, the belt will need to be shorter! The stock one is 925mm long. As you can see from the picture, just a bit too long. I ran some rope around the pulleys and came up with a measurement of 34" or 864mm. I need to go to the store and see what the closest belt is that they have available. I'm guessing an 875mm or a Gates 11M875. I'll keep you posted!
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I have thought about this a lot and have read a lot of people's experience with this as well as talked to quite a few people. I am not discounting your experience at all, but am wondering if when you converted what hardware you had in your system? Did you go with a new type compressor and condenser? A few knowledgeable AC folks seem to think that the condenser makes all the difference when changing over to 134. I can't really say, as this is my first time doing this switch. My thought is, given the expense of replenishing the 134 v. the R-12, I am willing to give it a try with all new accessories (condenser, compressor, blower motor, fans and hoses. Well all new, except the evaporator....) If I can't get the cooling I want from that, then I will have to switch back to R-12. Although, one could make a valid argument as to "why not go as cold as you can from the start?"

 

here are some shots of the "extra real-estate" I was referencing as to adding an additional blower motor, should I be required to go to plan B.... I just have to clean up all those pesky wires that don't seem to be tied to anything useful back in the engine compartment.... That footwell panel seems to be a good place to mount a relay for my blower motors. Hmmmmmm....
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i'd stay with R12, it blows colder.

PS: The Nick alu radiator is excellent.

 

Thanks for the feedback regarding Nick's radiator! I am chatting with him at the moment to see what we can do about some of my condenser fitment issues...