How cold is your A/C?

Basically, the AC system sucks.

The 328 AC is not improved over the 308 as far as the AC itself is concerned. The only functional difference is that the condenser is remotely located on the the 328 BUT it is no larger and the design of the "box" in which it is contained tends to restrict flow through the condenser due to the louvered cover behind it. The advantage to the 328's AC is its lack of effect on engine cooling. The condenser has no restrictive action on the car radiator and is one of the reasons for the 328's well-known ability to maintain engine temps in the normal range regardless of outside temps and driving conditions.

My 1989 328, with a fresh charge of 134 (converted to 134 by the Previous owner) was only able to keep cabin temps to what I'd call, "not quite as hot" in August temps on a cross country US trip several days after I bought the car in '08. I was sweating the entire 3k mile trip.

FWIW, here's what I did to make the system work pretty well nowadays though I have a slight leak that I need to address; the pressure drops internally over two years to necessitate adding some refrigerant. OTOH, adding a can every two years isn't horrible. MOST IMPORTANT - I learned to work on my own AC - two attempts at having AC shops improve the AC resulted in it working even worse! After a LOT of reading and research, I bought the appropriate gauges and a good vacuum pump. I now do all my own AC work (snd work for other folks as well). I have always done all my own mechanical work and, frankly, had no interest in learning about AC but I was basically forced into it.

1. DO NOT buy cheap Harbor Freight guages; spend 3x the money to get good ones. If you buy the 39 dollar HF freight gauges, you will later buy the $120 Yellow Jacket (or other) decent gauges. I learned that lesson so save the 39 bucks and the space in your trash can.

2. Removed the louvered cover behind the condenser, replaced it with 1/4" screen. That dramatically improved airflow through the condesnser, especially at low speed when you are depending on the fan to push air through. No one will notice the screen inside front of the passenger wheel-well if you spray it black. If you do concours, however, you are SOL.

3. I replaced the drier, the expansion valve, and all o-rings in the system.

4. I purged and recharged the system with Duracool (a propane-based refrigerant). I would have gone back to Freon - the original charge - but it was just too much trouble and Duracool's efficiency is even slightly better than Freon and much better than 134. CAUTION and IMPORTANT: : Propane-based refrigerants are not approved for use in automotive AC systems in the USA. They are actually illegal for such use in some states. They are approved in other countries and for stationary AC systems. It is generally felt that they WILL eventually be approved for Auto use because they are more efficient than current car refrigerants, have little affect re greenhouse gasses, and are relatively inexpensive. There are issues concerning flammability. Do some research and make that decision yourself. FWIW, refrigerant suppliers have been the major opposition to the US testing propane refrigerants for automotive use. Propane refrigerant has NOT been tested by the appropriate US Gov agency and found hazardous. The fact that it has NOT been tested is the reason it is not approved/legal.

With those changes, I have seen evaporator temps as low as 39 F and on a hot/humid CLOUDY mid-90'sTexas day, the cabin temp is comfortable with the AC temp control at around the 8-9 clock position with the blower on max. However, if the sun is shining into the windscreen/onto the dash, it cannot keep the cabin comfortable even at max temp setting. There is simply not enough airflow through the evaporated. If the sun is hitting from any other direction, again, cooling is OK.

SO, I guess what I'm suggesting as that with the stock system operating in top condition, if you are in areas of high temps/humidity, the system is marginal at best. However, much of that is dependent on your personal comfort level. I like a car's cabin to be quite cool - low 70's. Other folks prefer warmer. If you are comfortable with the cabin at 80, then the OEM system (Freon) running at max MIGHT be adequate. But it's just not much of an AC system by US car standards. No matter what you do with the refrigerant, the primary limitation is there is just not enough air volume/distribution from the evaporator.

There are aftermarket suppliers that provide more efficient systems for the 308 but none, AFAIK, for the 328. The major difference is a more efficient condenser and more powerful evaporator motor. I suspect the evaporator motor will work in either car but the condenser for the 308 will not fit in the small box where the 328 condenser mounts.

You CAN make the system work better than it does now but it will take some work and, IMO, will require either going back to Freon or using a propane-based refrigerant, at least if you want anything approaching decent AC. If you use a propane-based refrigerant, you should have some sort of sticker on the car near the service ports. AFAIK, no ac shop (in the US, at least) supports such refrigerants so it will become a DIY thing if you go to propane. I have no problem with that at all but other folks do.

 

Nice post, Mike.

Few thoughts I'll add:

I evacuated/vacuumed/recharged my 308 last week, with R134a. My condensor is (sadly) stock. Vent temps @ 80F ambient temperature are around 50F - with the top off, car sitting still. So that's a temperature reduction of over 25F degrees. So in an of itself, it's not a situation that R134 simply doesn't cool the air.

The windshield + dash is a very high source of radiating heat; I've seen people apply a 3M UV "tint" in an effort to combat this. Haven't tried it myself, but I've thought about it...

A modern condensor will improve the air temp from the vents. But as Mike said, the problem is there's just not enough air flow in the cabin. There's a limit to how much those tiny vents can combat the sun beating down on the car.

On propane-based refrigerants such as Duracool: while the EPA hasn't approved them (and have not tested them for MVAC), that doesn't mean they are banned simply because they haven't been tested (nor because they are flammable). Those refrigerants are approved for other uses, in systems designed to use them. Note there's a big difference between "designed" and "retrofit". EPA (in my opinion) simply doesn't bother testing refrigerants that they believe are inherently a bad idea. R-152a, for example, is flammable - but it IS approved by the EPA. But again, not as a retrofit substitute.

 

To complement what has already been said.
1. The radiator rejects its hot air used for engine cooling right in front of the windshield. This makes the windshield quite warm which heats the AC air leaving the vent by convection.
2. The targa top is poorly insulated. It gets warm even when the car is in motion.
3. The windshield extends rearward quite a bit allowing overhead sun a direct shot onto one's legs. Secondly, it provides a large area for the sun to enter the vehicle.
4. The side windows slope inward, again allowing our bodies and car interior to be the targets of the overhead sun's rays.
5. Sun's rays (short wave length) easily pass through the windshield and heat the black top of the dash. The dash top emits long wave radiation which does not pass back through the windshield remaining in the vehicle to add to the discomfort. Glass acts as a filter passing short wave lengths but not passing longer wave lengths.

 

It's bit colder than this now but the only picture I have ☃️

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I used to get 1 deg centigrade on the old gas (R12 or whatever it was). Now that's no longer available I get around 8 deg C like Paul.

As others have written it's the size of the vents that is the big decider. Thye are totally inadequate and badly placed. You get a frozen knee if you want any effect. Heading south with the sun on the windscreen, it can just about cope for a few hours with high european temps (say high 20 to low 30 C) if the interior starts cool. No way will it cool if the interior temp starts high. Much better heading north with the sun behind. Can be pretty comfortable all day. The radiator effect of the windscreeen is a major factor.

 

We are fighting a solar screen windshield and hot air that blows in thru the foot well. It's a losing battle - especially if you are running 134 with the stock components.

 

I just roll my window down.

 

When I'm sitting there in traffic, with the sun beating down on my head and legs, chugging Gatorade to stay hydrated, I'm never thinking "'I bet with r12 this would all be perfectly comfortable."

 

I just got a new windshield on my 328 - from a golf ball that smacked it at 70mph... so while it was in the shop for 3 months, I had them put on the UV tinting on all the glass windows... and had the AC recharged R12. So on the day I picked it up - it was bumper to bumper traffic all over Atlanta, and temp was about 90F outside moderate humidity... and the car was very comfortable at a stand still and actually great when moving.

the problem ( and this is consistent in 308's as well ) is there is no left hand vent for the driver or Right hand vent for the passenger.. so all you get is cold air low from the center. so you knee cap is cold while the left side of you is warm. the UV tinting seems to work. I had the car out at our monthly gathering sitting in the sun and got in windows up - and in 10 min I was cool while driving in regular city traffic. having it on while on the Highway - its very good.

The flow of air from the fan is nowhere as strong as a modern car ... and I've always wondered if you can put a stronger motor down there to push more air? regardless its just never going to be great... the best you can hope for is ok. My car is black... so it soaks up the heat.

 

I had my entire AC system re built, after 20 years of non operation , in my ownership . Its gets to about the low 7.2 s C so its working really good, I can even dial it down after initial cooling, and for the inferior system it is, says a lot . I would say that if any of you guys decided to completely re build your system , you would get good results. In my estimation, everything has to be new in order for you to get the upmost in cooling.

 

Yep, it's air volume! Our Hyundai Santa Fe cannot get the evaporator discharge temps near as low as my 328 can - low 50's F is about it. BUT it can move a huge volume of air across the coils and distribute it better so even though temps at the evaporator are 10-12 degrees F warmer than my 328, the Hyundai (and any other modern car OR any US car built since the 60's) will freeze you out of there regardless of outside temp/conditions.

I have thought about the higher capacity blower motor that some of the aftermarkets supply. Might help but the distribution still sucks.

Opening the windows/top off is not a workable option for me in TX in the summer!

 

Temperature out the vents is not a problem. Its the volume of air. Remove your vents and the volume of air will increase. I use R12 which is colder. You need a bigger condenser if you want to get better results with R134. There is a company in Carrollton,Texas that sells a upgraded blower motor and a adapter plate. You have to have the adapter plate to install the new blower motor. I will post pictures of the upgraded blower motor and adapter plate when I find them.The volume of is much better.

 

Hello Mike,
Your quote is very interesting, first time I hear about propane-based refrigerant. Over here all you can get is 134 and a Kg costs about 80 Euros
Do you know if propane-based refrigerant is available in Europe?

Thanks in advance,

John.

 

John,
I believe Duracool (one of the propane refrigerants) will ship anywhere - at least their website implies that they can but they will only take online orders to the USA but you can call/contact them to get the specifics. Here's a link to their site: http://www.duracool.com/Duracool/purchase.html Duracool 12a is the appropriate product for the car AC. There are other propane-based refrigerants; DuraCool just happens to be the one I use.

 

I dont turn mine on much. It drives the coolant temps up too much.

 

The 308... where the specific heat capacity of the driver is part of the car’s cooling efficacy


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My system blows ice cold. Its like a hamster blowing on an ice cube!

 

Thanks!
Another question: Regular Freon (R12, 134...) are chlorine based and propane is a hydrocarbon based. Could there be any issues with the hoses?
Just wondering.

John.

 

FWIW, Freon is R12. No refrigerant other than R12 is "Freon." "Freon" is a Dupont trademark name for the refrigerant they invented which they called Freon and other companies called R12 so they could produce it as well!

And far as the hoses, there is no issue with the propane. In fact, since propane molecules are larger, propane is less prone to permeating the hose than Freon and FAR less prone to do so than 134.

 

R12 is no longer manufactured and is strictly controlled. Only people licensed by the EPA may legally buy or sell R12 which is always now NOS.

 

What AC?
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I don't understand all the AC issues on 308's. Mine works pretty well on most winter days.