Beat the Arizona Heat - My custom AC system build Options

[AZBanks]

I've created a few threads with vague titles but I'm hoping the title of this thread is pretty clear.

There are places in Arizona where the summers are pretty nice. Those are the places up in the higher elevations of Arizona.

I don't live in one of those places. I live in Phoenix.

As you may have heard, Phoenix is hot in the summertime. Driving a car without AC in Phoenix in the summer time is pretty miserable. Car dealers don't sell cars without AC in Arizona. Satan keeps a winter home here because the summer are too hot.

OTOH, it's a dry heat and I never have to shovel it.





The NARP is a 71 914 that started life with a 1.7 liter engine. I had a 1.8 liter engine sitting in the garage for my other 914 project and when the 1.7 got too aggressive in marking it's territory I decided to swap in the 1.8. I also swapped in an transmission I got from Oscar at the same time.

The 1.8 came with a boat anchor of a York AC compressor connected with a side mount on the passenger side of the engine. I removed that almost as soon as I got it home.

I picked up the 1.8 a couple years ago from Patrick Motorsports for a GREAT deal and James said it came out of a running car so I thought it was good to go...

I had never looked it over as well as I could have. I've known James for several years and trusted him and I still do. I never asked or looked at the engine to see about oil leaks. It really could have had a hole in the case and it still would have been a good deal so I don't want this to sound like a complaint about James or PMS because it is not.
I cleaned a LOT of crud off the 1.8, replaced the front crank seal, swapped the engine tins from the 1.7, and installed it and James was correct, it runs great.

It was still dripping some oil and I wanted to add an AC system so it is back out of the car less than 500 miles since it first went in.

I've tracked the oil leaks to a couple push rod tubes so all the push rod tubes are getting new seals.
Another reason I dropped the engine was to replace the shift input shaft seal on the transmission. It was the only seal I didn't replace last time I had it out of the car and of course, it just had to leak. (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/headbang.gif)

It didn't help that I put Swepco oil in the trans before I installed it the first time. The good(Evil) Dr. set me straight so it is now running good old 90 weight Dino oil.

The transmission now has all new seals and is ready to go back in the car. The engine will have the new push rod tube seals and oil cooler seals to go with the new front crank seal I put in before the first install.

So there is the background on the engine and trans. Now it's time for the AC system.

This is a total experiment based on other AC threads here and on the bird and based on systems and guess-timats from other cars. I made some of my guess-timats based on parts and sizes from my 1990 944 S2 Cab. The cabin of the 94 is a bit smaller than the 944 cab so parts that can cool the 944 should be about the right size to cool the cabin of the 914.


As I said, the 1.8 liter engine came to me with an OLD York compressor. I did not want to use that massive HP hog. There was a decent pulley mounted behind the fan but it is also a heavy piece of steel.

I bought an original dealer installed style AC system a few years ago from some one either here or on the bird board(I don't remember which and it doesn't really matter at this point). I bought it mainly for the under-dash evaporator and the controls.


The NARP never had AC so it is not hacked up. It has 99 problems but ragged holes in the body and front trunk for AC aren't any of them.

The engine tin on the passenger side of the 1.8 is hacked up and bent up pretty bad. I should have taken pictures before I started cleaning it up. I am going to finish cleaning it up and paint it. I don't want to hack up the good tin that was on the 1.7. I'll save that and hack it up for my next project.
(IMG:style_emoticons/default/sawzall-smiley.gif)

With the advances in modern compressors, condensers, and fans I decided to try an installation with the condenser mounted to the underside of a GT style engine lid.


In addition to the original style under dash evaporator, I am using a Sanden sd5h11 6333 compressor. It is the modern equivalent of the SD507 and is designed to use R-134a. I will be mounting it to the passenger side of the engine with amount plate I got from Gilmore Enterprises out of Las Vegas. Their website (gilmore-enterprises.net) doesn't list parts for the 914 or any individual parts but Ed, the owner is super easy to deal with. I called him up, told him what I was looking for, and it was on the truck heading out to me later that day.

I picked a universal fit parallel flow 11" X 21" condenser and 2 high flow, low profile 10" fans and a drier with a trinary switch.

[AZBanks]

Working on the lid.

[AZBanks]

I still have a bunch of hose and a bunch of fitting to to buy.

I did pick up a hose crimper to make my own hoses.

[SKL1]

I guess I don't suffer quite as much in north Scottsdale as it's 800-1000' higher (IMG:style_emoticons/default/smile.gif)

AC would be nice but I just can't cut up the car- just drive it early in the day or take the 911 (or the wife's Audi) if it's really "warm."

I used to cry in the old days when I'd see a 914 totally butchered from a "dealer installation."

Good luck with your install...

[bkrantz]

I lived in Tucson for most of the 80s, and never had a car with working A/C. Our survival mechanism in summer was to keep moving. As we said back then, cars with the windows rolled down in summer had the right of way.

[AZBanks]

I hear you about the "hack jobs". I couldn't believe how bad someone hacked into the engine tin.
I'll get it cleaned up and trimmed as close to the new AC compressor as I can. I want people who don't know any better to think it looks like a factory job.

The only other part that I am hacking up is the engine lid and I'm trying to get that right as well. I started on it tonight and I still have a bunch of shaping and fitting to do before it's done. I like the GT lids anyway so it's possible I might have done this with or without the AC system.

[AZBanks]

I will have a couple small holes in the body to run the lines into the cabin for the evaporator. I'll be using the newer reduced diameter hose to keep the holes as small as possible.



The lid still has a long way to go.

[ClayPerrine]

From experience, and from working with my father (he designed automotive AC systems), you need a bigger condenser. That one is too small, especially if you are running 134A.

I will be following this closely.
Clay

[Coondog]

Great post... (IMG:style_emoticons/default/first.gif)

[76-914]

I wonder if the warm air of the condenser will affect engine temps. Good call on the rotary compressor. Much more efficient, smoother and draws less HP from the engine. (IMG:style_emoticons/default/agree.gif) with Clay. The condenser determines how cold it blows. If you find it isn't enough look at Keith's - aka @914toy - additional condensers that he added to the rear wheel wells.

[AZBanks]

From experience, and from working with my father (he designed automotive AC systems), you need a bigger condenser. That one is too small, especially if you are running 134A.

I will be following this closely.
Clay

The condenser size is one of my guess-timates. (IMG:style_emoticons/default/confused24.gif)

11 X 21 is bigger than the condenser in my 944 Cab and it has no trouble keeping up with the Phoenix heat using 134A.

If it does not keep up, I have enough space to fit a much bigger condenser under the engine lid and universal fit condensers are surprisingly affordable. Although, a bigger condenser will require bigger fans and then it all starts to add up.

[AZBanks]

I wonder if the warm air of the condenser will affect engine temps. Good call on the rotary compressor. Much more efficient, smoother and draws less HP from the engine. (IMG:style_emoticons/default/agree.gif) with Clay. The condenser determines how cold it blows. If you find it isn't enough look at Keith's - aka @914toy - additional condensers that he added to the rear wheel wells.

Airflow over the condenser is one of the biggest questions I have running through my head.

The first part of that question is what direction does the air go through the engine lid? Is cool air flowing down through the lid into the engine compartment or is hot air flowing up out of the engine compartment?

I don't want my fans to be fighting against the normal flow of air.

If the normal flow is down, I wonder the same thing you asked, will the heat from the condenser effect engine temps?

If the normal flow is up, will the hot air from the engine effect the efficiency of the condenser?

Does the flow change depending if the car is moving or sitting still and how much effect does vehicle speed have on air flow?

If my car was running, I'd attach some string to the engine lid grill, point a go-pro at it and take a drive. That is hard to do when it is up on jackstands with the engine and transmission out of the car.

Does anyone with a GT style lid have a go-pro, some string, and some time??? (IMG:style_emoticons/default/idea.gif)

[slowrodent]

AZBanks,

Thanks much for initiating this thread. I, too, am an Arizona desert rat (Oro Valley) and am putting together a 914 with a non-Porsche, water-cooled engine. So my system will indeed be "custom" as well. My approach will be a bit different, with a front end condenser, but I'm sure I'll learn all kinds of good stuff from your design.

Keep up the good work!

[slowrodent]

PS.. I had sized my condenser to be very similar to yours..

[Chris914n6]

Use bulkhead fittings into the cab & thru sheetmetal.

The rest of the design is fine.

The grill is way bigger than the slit provided with the rain tray installed.

[ClayPerrine]

From experience, and from working with my father (he designed automotive AC systems), you need a bigger condenser. That one is too small, especially if you are running 134A.

I will be following this closely.
Clay

The condenser size is one of my guess-timates. (IMG:style_emoticons/default/confused24.gif)

11 X 21 is bigger than the condenser in my 944 Cab and it has no trouble keeping up with the Phoenix heat using 134A.

If it does not keep up, I have enough space to fit a much bigger condenser under the engine lid and universal fit condensers are surprisingly affordable. Although, a bigger condenser will require bigger fans and then it all starts to add up.

With R-134a I had to add an additional condenser from a 911 SC under the engine lid on Betty's 914. It was run in series with the existing dealer installed DPD condenser in the front trunk. I put two fans on the engine mounted condenser, and a larger fan on the condenser in the front trunk. That made it get really cold inside on a Texas summer day.

The Condenser to Evaporator size ratio and the compressor efficiency is what you have to calculate to get the AC cold. In doing the one on my red car, I am using a modern 16 x 12 condenser in the front trunk. with the added efficiency, it should be able to keep up with the heat load. I am probably going to add a second 16 x4 condenser in series mounted in the exhaust side of the front trunk opening. Air will flow through the big condenser, and then exit out through the little one. If I pass the refrigerant through the little one first, the condenser will be hotter than the air passing through it, and it will drop the refrigerant temp before it gets to the big condenser. That will make it more efficient.

What are you doing for an evaporator?

Clay

[914_teener]

From experience, and from working with my father (he designed automotive AC systems), you need a bigger condenser. That one is too small, especially if you are running 134A.

I will be following this closely.
Clay

As much as I hate to admit it....the two guys from Texas are probably right.

[AZBanks]

Use bulkhead fittings into the cab & thru sheetmetal.

The rest of the design is fine.

The grill is way bigger than the slit provided with the rain tray installed.

I will put bulkhead fittings on my list of things to buy. Thanks for the tip.

What is this "rain" tray thing? What is "rain"??? We don't get that here. (IMG:style_emoticons/default/stirthepot.gif)

[AZBanks]

From experience, and from working with my father (he designed automotive AC systems), you need a bigger condenser. That one is too small, especially if you are running 134A.

I will be following this closely.
Clay

The condenser size is one of my guess-timates. (IMG:style_emoticons/default/confused24.gif)

11 X 21 is bigger than the condenser in my 944 Cab and it has no trouble keeping up with the Phoenix heat using 134A.

If it does not keep up, I have enough space to fit a much bigger condenser under the engine lid and universal fit condensers are surprisingly affordable. Although, a bigger condenser will require bigger fans and then it all starts to add up.

With R-134a I had to add an additional condenser from a 911 SC under the engine lid on Betty's 914. It was run in series with the existing dealer installed DPD condenser in the front trunk. I put two fans on the engine mounted condenser, and a larger fan on the condenser in the front trunk. That made it get really cold inside on a Texas summer day.

The Condenser to Evaporator size ratio and the compressor efficiency is what you have to calculate to get the AC cold. In doing the one on my red car, I am using a modern 16 x 12 condenser in the front trunk. with the added efficiency, it should be able to keep up with the heat load. I am probably going to add a second 16 x4 condenser in series mounted in the exhaust side of the front trunk opening. Air will flow through the big condenser, and then exit out through the little one. If I pass the refrigerant through the little one first, the condenser will be hotter than the air passing through it, and it will drop the refrigerant temp before it gets to the big condenser. That will make it more efficient.

What are you doing for an evaporator?

Clay

Are you using old tube and fin condensers or newer parallel flow condensers on Betty's car?

"Size ratio"?????, wait, there is math involved, I am so screwed!! (IMG:style_emoticons/default/headbang.gif)

Your series condenser plan 16X4 > 16X11 gives you 25 sq/inches more area than my single condenser

I admit, I was just winging this based on a few threads and other documentation I picked up along the way.

Some of those docs talked about the greater efficiency of the newer parallel flow condensers and newer compressors. I was thinking that would be enough to get me to my goal of cold AC. Now I've got to research size ratios.

My current plan is to use the under dash evaporator from an original dealer installed AC system. I have that stored in my parts stash. I guess I need to find out the size of the evaporator. What is the size ratio I should be shooting for?

I do appreciate the info. Anything I can learn to keep me from screwing this up is a great thing.

[ClayPerrine]

With Betty's car, we were using the original dealer installed tube and fin condenser and evaporator. So we had to add a second condenser to make up for the losses of the 134a. With my car, I will be using new parallel flow condensers, and a parallel flow evaporator core.

I would have to look up the maths needed to figure this out. My dad knew them from memory. But he used them all the time when he was working. We worked out the required evaporator and condenser sizes for my car before he passsed. I am adding the second small condenser as a "fudge factor" to insure it is cold.

Also, the parallel flow condensers are thinner than the same size tube and fin units. So the box in the front trunk will be shorter. (IMG:style_emoticons/default/piratenanner.gif)

Clay