I "WWested" my 84's a/c system
 

Hi guys,
I know many of you have opinions on WWest's a/c advice. While I don't agree with everything he says, I think he does make some excellent points.
I have a full Retroaire system that i installed last year. New hoses, compressors, heat exchangers, fans; everything. It still did not perform as well as any cheap modern car with a/c. I have decided to enhance my current system with several of Mr. West's suggestions:
I have tinted windows (already had them.)
I have back dated heat with SSI's, but I reinstalled my engine fan which now blows (a lot of) air out the bottom of the engine bay.
I added two 8" puller fans that come on with the a/c clutch. They run off a relay and separate fuse. They each pull 2.8 amps and 1600 CFM.
I don't have a trinary switch (I do have a r134 high/low switch).
I also have a California Pop Top which is a white Tyvek partial car cover, to help keep the car from overheating while parked in the Sun.
Here's a picture.
We will see how it works in a few months when our Chicago weather goes from cold to hot.
Thanks for looking,
Dave

http://forums.pelicanparts.com/uploa...1425765466.jpg

What made me go the fan route was my research into the 964 a/c system. It uses a single front wheel well condenser with a 10" fan that really pulls a lot of air. This single condenser is smaller than our deck-lid condenser yet it cools very well. Admittedly the 964 evaporator and blower is probably better as well. I decided that maybe we don't have inadequate condenser area, but we really have inadequate condenser air flow. I am not the first person to think this, and Mr. West is probably not the first either. Anyway I had a couple of fans lying around, so I mounted them up. They just barely fit, and they do not have a proper shroud, but they probably cover 50% of the condenser.
We'll see how they work.
Dave

Interesting, I just received my full retroair kit and I'm working on installing it. I have my engine compartment blower hooked up to a switch so I'm going to see how it works to pull extra air. Where did you get this California topper?

I used the wrong name for the car cover. It's a California Pop Top sold at capoptop.com. In anther car I owned which was dark green, the inside temps would be 140 on a 90 degree day, parked in the Sun. With the cover, it would be the same as the outside temp. No greenhouse heating.
Dave

AC Updates
 

Hey Dave,

Looks nice and it will be interesting to see how it handles the heat and humidity (once we get done with this winter). It looks like you're having the heater fan in the engine compartment simply fed without the air ducting from the driver's side engine duct. I like the look without all the extra ducting if it blows enough air through the SSI heat exchangers.

Hi Jack,
The engine fan just sucks air through the condenser and blows out on the ground. My heat is dependent on the shroud fan, and footwell blowers to move air through the heat ducts.
Take care,
Dave

Isn't the engine kinda sorta sealed?

Hi Bob,
The engine compartment is indeed sealed, and that's good. However, there is a sealed hole in the engine tin where the electric engine compartment blower discharge duct passes through to get to the heat exchangers. When you backdate the heat, usually that hole is eliminated, and indeed the whole electric blower and duct too. I decided to leave the blower in place along with its discharge duct, and the sealed hole. This lets the blower suck air in through the condenser, and blow it out on the ground. The SSI heat exchangers only get air blown into them by the engine cooling shroud main fan. I also have foot well blowers to boost the heat flow.
Dave

OK - different than the SC. You have an "out". Cool.

Is that a stock condenser?

That is the Retroaire parallel flow condenser. I think it could be done with the stock one as well. There are also lower profile fans than I used.
BTW I am skeptical of their 1600 CFM rating, but they do move quite a bit of air.
Dave

I was just curious because it looks very different from mine.

Clearance in the engine bay is going to be a variable for others. In my '83 if I have the coil sitting too far up in the mounting bracket it interferes with the condenser, so very little room to work with. Your engine bay looks like it has a good bit more room. I am seriously considering going to a 3.6 and I've been told I might have to eliminate the decklid condenser if I do.

Good luck with the project.

Hi Dave, I am in Miami and so far the full RetroAir kit has not needed added fans, even in traffic, but certainly added fans can't hurt. My comment would be to add the trinay so that the extra fan turn on only when necessary, maybe even staged.
In my 87 I found the oil temp getting uncomfortably high even though it was cool inside while in traffic so I lowered the oil cooler blower temp switch setpoint. Like you though, have to wait until summer to test it.
BTW, I see you went with the Nippondenso I went with the Sanden.
Cheers,

I didn't mention that I put headers and removed all heater components, fwb included, and made a blanking plate to cover the hole in the engine tin. Your solution to use the hole is what I would have done.

Clean engine Dave... compliments. Am interested to see what vent temps you get come summer. Will you say what weight of 134 you loaded?

Just as a thought. I added neoprene around the condenser and rubber seals around the trunk lid to force all air through the condenser. The top one is my 911 - which because it has PMOs has no room for a fan and the lower is my 912.http://forums.pelicanparts.com/uploa...1425830539.jpg
http://forums.pelicanparts.com/uploa...1425830560.jpg

Thanks Laurence, I already have seals on the sides, but may add on top and bottom.
BTW I was not happy with the zip tie type fan mounts as a definitive mounting, so I made an aluminum bracket to add mechanical support.
I cleaned up the wiring a little bit too.
Take care,
Dave

http://forums.pelicanparts.com/uploa...1425840517.jpg

Instead of adding a trinary switch you could tape and insulate one of these to rear lid condenser inlet fitting. Don't know what temperature "trigger" level to suggest, some experimentation is due.

Strange as may seem the heat exchange process become more efficient the greater is the differential between the two mediums. Plus, not need to run the blower/fans unless there is a need.

http://forums.pelicanparts.com/uploa...1425843753.jpg

I like that switch, and may try a couple of different temps. Anybody got a recommendation for temp at say the inlet pipe of my condenser. Or maybe it should be at the outlet of my condenser?
Thanks,
Dave

Improve CFM by 50%

And another point in favor... Cabin heat level no longer varies with engine RPM.

http://forums.pelicanparts.com/uploa...1425844940.jpg
http://forums.pelicanparts.com/uploa...1425845025.jpg

You didn't need a separate switch, lifting one of the heating control levers just enough to start he blower would suffice.

Pelican Technical Article: 911 Cooling Boost

The switch can be placed anywhere in the high side, IIRC Porsche once used one, screw-in stud type, attached to R/D.

Looked up SSI heat exchangers and I must say I'm puzzled, how does the engine shroud fan blow air through your SSI heat exchangers?

Plus, what about the heat control module function that helps to cool down the engine using the cabin heat blower?

++, Isn't it unwise to run the footwell blowers without the cabin heat blower creating positive pressure in/at the flapper valves?

You are correct, Mr. West. The SSI's are basically copies of 1972 911 heat exchangers, made in stainless steel. They eliminate the catalytic converter, and use the 72-style muffler. The main engine cooling fan is connected to the SSI's by duct pieces from older pre-electric blower cars. I, myself, just use the electric blower as a suction fan that pulls air through the condenser and blows it out the engine tin. You are correct, this arrangement eliminates the additional cooling function, but the fan would be on anyway. There is also a theoretical chance of sucking exhaust gases into the cabin at very low engine RPM's. In reality the foot well blowers don't pull all that well compared to the engine fan.
These mods are part of the heat back date process. It simplifies the system and does eliminate certain of the later models' features. For better or worse.
Dave

I simply mounted the fan to the condenser by pushing fins aside and running a bolt right through and using a fender washer on the non-fan side.

You're so smart!
Great idea. I always do things the hard way.
Thanks,
Dave

Last we heard your retroaire system was not quite up to snuff, had to rev-up the engine at times, have you made more improvements?

I don't remember complaining but I'm OK with the system. It's not fantastic but it does the job - never great when stuck in traffic. The fan and the sealing described above seem to have helped in that situation. Not certain it's ever going to be good enough for my wife in the San Antonio summer but it's a whole lot better than nothing.

My latest project (a backdated 83) has a single 964 condenser mounted in the front left fender with a 10" fan pulling air through air ducted from grills in the front facia but otherwise the same set up. I'll report on how it works out

Interesting, Laurence. I could not find a way to fit the condenser in the front wheel well of my 84. I was willing to pull the washer bottle,, overflow tank and even the fog light, but still I could not make it fit. I would love to see some details.
Thanks,
Dave

I just want to clarify. My Retroaire system works great in steady state performance. I get mid 30 to 40 degree vent temps in 90-95 degree weather. My problem is dealing with heat soak. My car is typically 140 degrees inside, and it take 15 minutes for the vent temps to drop into the 40's. I typically have a 20 minute drive home, so I am hot for most of the way. Once the system catches up, it seems to work just fine.
I will recheck my T & P's once the weather warms up, and report all, with and without fans.
Take care,
Dave

I didnt have any major issue. ill take photos when i have it up the lift. I couldnt fit the factory mounts or fan so I used a flat 10" fan i bought on ebay but the condenser itself fit with no problem. Mine is angled in the same way a 996/986 radiator might be (probably about 60 degrees from straight) and with help of neoprene and aluminium I have enclosed it so that one end of my centre oil cooler hole (I used a shorter oil cooler), my horn grill (remembering the car is backdated) and an extra opening cut into the bumper below the horn grill all feed around and into the front of the condenser. The fan is mounted behind the condenser and sucks air into the wheel well. Photos wil make this a little clearer. As I said earlier I havent tried it yet but I'll let you know.

Just ocuured to me that one other tyhing that may make a major difference is that, because my car is a backdate, I was able to remove the front bumper mounts. Probably couldnt have done it without doing so. That may be the key.

It is great you are going to put to the test the theories of Wwest. That is the true measure of any theory. Please report back you finding once it gets hot. Good work!

Nice little mod!

"Heat Soak" quick cool-down procedure, not that you don't already know, just covering the bases.

a) Max A/C.. of course.

b) Windows down 1/2"

c) Fresh air blower ON.

b, c, long enough to remove the HOT cabin atmosphere, maybe even for a slightly extended period to somewhat cool down the cabin interior surfaces.

Almost a shame we can't reverse the A/C airflow route to help move the HOT air up and out!

What about a Trinary switch? Did i miss that?

See post #18...SmileWavy

I have a brand new Trinary switch that I purchase but, never installed it. If any of you AC experimental types want it let me know via PM and I will send it to you for free. It is a Red Dot which I believe wwest is using. It also includes the plug coupler which makes it easier to wire in to the system.

I actually purchased two thermostatic switches that clip onto the discharge pipe from the compressor (1/2"). I selected 130 and 120 degrees, to choose which to turn on the auxiliary fans. I don't have them yet, but I don't have any hot weather yet either. One of those switches plus my binary switch should be the equivalent of a trinary.
Again I will report when hotter.
Thanks,
Dave

What about a Trinary switch? Did i miss that?

Dick,
See post before. The response crossed the question in cyberspace,
Dave