bigcoupe.com

I've just had the a/c gassed up after years of neglect. The system shows no immediately apparent leaks or malfunctioning components and the 134 gas has been installed with lubricant and dye to keep things functioning, or if needed, make fault finding easier.

My question is, what should I be expecting from the 635 system. On the highest fan speed, the air flow is reasonable from the center vents but faint from the outside units. The capabilities of the system to cool down the interior is poor and if your driving into the sun, the feeling of air flow on the body stops at the hands on the wheel.

Question is - Is the system able to keep up with 30deg+ days or should I just always plan my drives so the sun is behind me.

I'm not expecting modern day capabilities, I'm just not sure what these systems should be like or how efficient they should be as all vehicles I test drove before this purchase had non functioning systems so I have nothing to compare it with.

The standard system is somewhere between reasonable and inadequate, especially using R134a as opposed to the original R12. I am currently upgrading my system to a parallel flow condenser and 7 piston Sanden compressor. Highly recommended is Rob Siegel's (Hack Mechanic) most excellent book, Just Needs a Recharge. https://www.bookdepository.com/Just-Nee ... 0998950716

For detailed information on A/C system upgrades, look up Songs thread or my LOCUTUS thread.

baders,

Thanks for the links to Songs and your air conditioning forum links. Plenty of reading.

I've been thru a similar lack of performance with my earlier Volvo 242 upgrade where the standard components were suitable for Sweden, not Aus, still I was able to get it operating reasonably using the standard components, but, had I kept the car, I would've changed everything over similar to your conversion.

Since my first post, it would appear either the new gas has disappeared or the compressor has failed (motor doesn't complain when a/c turned on). Either way, I'm back with no cooling. As the system was loaded with dye, that will be the first check but if its the compressor, I'll be looking to upgrade components as you and Song have done.

Out of interest, do you get much airflow from the drivers side vent. Mine is a suggestion of air, not a force of any note.

Here is my thread on the upgrade I completed to my system.

viewtopic.php?t=21047&highlight=

Jose

bigboystoy wrote: ↑Mon Mar 04, 2019 10:22 pm baders,

Thanks for the links to Songs and your air conditioning forum links. Plenty of reading.

I've been thru a similar lack of performance with my earlier Volvo 242 upgrade where the standard components were suitable for Sweden, not Aus, still I was able to get it operating reasonably using the standard components, but, had I kept the car, I would've changed everything over similar to your conversion.

Since my first post, it would appear either the new gas has disappeared or the compressor has failed (motor doesn't complain when a/c turned on). Either way, I'm back with no cooling. As the system was loaded with dye, that will be the first check but if its the compressor, I'll be looking to upgrade components as you and Song have done.

Out of interest, do you get much airflow from the drivers side vent. Mine is a suggestion of air, not a force of any note.

I get "OK" air flow from the drivers side vent. Perhaps the ducting has popped off ? Are you running the original wingcell compressor ? I think Jay Stratton provides a full refurb service on them.

viewtopic.php?f=2&t=29368

Unless you have a super low mile, true collectible I would not refurb. I would switch out to a modern Sanden or Nippondenso compressor, and run R134, or the new R1234. Better yet, I have experimented with using the "canned air" conversion (tetraflouroethane) in my Saturn, and it performs fantastic.

In my thread, you will see that HC12A (isobutane) refrigerant is actually THE ideal gas to use for your AC. It requires zero changes to R12, R134, or even commercial R430 systems. The gas can be purchased online, you actually use less of it, and it is more efficient in older compressors. The key criticism is that it is highly combustible, but it has been used in other countries by commercial vehicle companies with no mass reports of disastrous failure. If an A/C system does leak, it is usually in minute amounts. Total failure of a seal/hose is not common. I actually converted my motorhome (1983 Ford 460 based) to an isobutane based gas, using a Denso compressor. It works absolutely great.

Bottom line is that there are many conversion options, so if you are looking at rebuilding an old, inefficient pump, I would highly recommend upgrading to more modern components.

Jose

This morning I had the a/c mechanic look over the system and it was discovered the compressor had a small leak from a front seal and the TX valve was jammed closed. No wonder the amount of 'coolth' from the system was poor as the gas couldn't circulate.

So, going on his years of servicing a/c units, he's recommended I install a new Sanden compressor, together with new TX valve and drier. As for the condenser, he didn't believe there was enough of a gain from a new parallel flow unit to warrant the cost or the effort involved. As this is the second old a/c unit I've played with over the last 5 years, he's the second a/c mechanic to indicate the original serpentine condenser is not a hinderance to achieving the best result.

For the moment, I'll defer to the professionals knowledge base and see how things go. No time to hurry this now as it would appear our run of hot weather has come to a grinding halt, again.

A new parallel flow condenser is a cheap way of increasing performance and these systems need all the help they can get. Think I paid around AUD$30.00 for my 16 x 19" version. You do need to modify brackets however and perhaps the "pro" is balking at that ? At the very least, he should be looking to flush the serpentine condenser and also your evaporator (whilst replacing the Tx valve). A Sanden 508/708 style compressor will also require modified brackets. Going the Sanden route, some of the knock off versions perform well, but I went with a genuine Sanden SD7H15 HD (7 piston).

Genuine Sanden unit to be used, with installation handled by my good self. I've read the various post on what's involved so at least I have a starting point. A/C mechanic will be responsible for hoses, flushing and gassing.

A quick check of condenser prices show local items are $200 - $300 but US items can be had for $120AUD delivered. As this will be done over coming months, I have plenty of time to consider my options.

Look at my thread, and you will see I installed a 19X16 condenser quite easily. Your mechanic should be able to handle it just as easy if he can crimp his own hoses.

Jose

There are a lot of Sanden clones out there at very low prices. I'm not sure how inferior they are vs the real thing. Also it seems to be hard to source the correct real Sanden. There are ad words to be wary of: "Sanden type" "Sanden style". I'm told the only way is to look at the tag riveted to the compressor itself.
--Ken

My AC was inoperable. Sourced NOS condenser from the US. Leaked
Second go they had incorrectly fitted compressor seal. Leaked again.
This time NOS compressor also from US.
Had originally stuck with R 12. With new compressor the latest gas.

Doesn’t perform to Daly at all. Top slider full left. Other two full right. Fan has pretty good puff.

Car is original enough to keep stock. Cheers

Fellow Forum Members,

If your car has a Behr/Bosch A/C Compressor with either R12 or R134, I can rebuild your 30 year compressor with new seals and bearings.
This Behr/Bosch unit is also called a Wingcell.

I can rebuild your Wingcell for $235.00 + return ship

Then you do not need to mess with trying to fit the adapter brackets. Or having the incorrect hose fittings.

The Wingcells are very well made, with German Engineering. And are ready for another 30 + years service.

See my footer for my LINK, then read, and got to # 12

Best,

I updated my system to R134 a couple of years ago and learned a few things in the process.

-In addition to different o-rings there are a couple of flex lines attached to the compressor that couldn't handle the R134 and were a source of leakage. These needed to be replaced with hoses with a higher pressure rating.

-R134 is more sensitive to R12 in terms of the amount of it in the system. If the amount of R134 in the system is a little low or high the cooling can be significantly degraded.

-I saw significant improvement in the system after having the original condenser refurbished at a local radiator shop.

Overall I'm pretty happy with it, even in the hot Texas summer. I'm running R134, the original compressor, like new condenser, and new blower.

Regards,
Tony

It is important when assessing an E24's air-conditioning performance to RTFM (Read the Flipping Manual).

The manual states to move all the three slider controls fully to the left, the closed position, in order that no exterior temperature air is allowed in and that the cooled air is directed to the face level vents.

Cars can differ though, as on my 1982 (very early E28 based car) the cooled air only comes through the dash top vents (not the windscreen vents though) whereas the cooled air comes through the fully adjustable vents on top of the AC panel on my 1985 M635CSi.

To enable directional control of the cooled air on my 1982 car in the summer I now fit the earlier, E12 based car, dash top vents which can be fully adjusted for direction; it takes minutes to do and allows a coller car in the summer.

Quick update of the progress towards proper air conditioning for next summer (only 6 months away).

Obtained 16"x9" condensor and installed without any issues. Re-using the factory fan as it works well and pushes plenty of air.

For the compressor install, I took a different approach for the adjusting method as the original factory adjuster plate was stuffed. The pictures tell the story of what I came up with. Next on the list is the removal of the interior evaporator to install new TX valve and new seals. Just need to stop driving it at every opportunity so work can be done properly. After that, new hoses, re-gas and its done.

Now THAT is all kinds of clever!

So, after some time I've gotten around to removing the evap unit from under the dash.

What I discovered was not pretty but it did explain why air flow was very questionable. It was also discovered that one of the counter balanced flaps was inside the evap unit so I somehow need to get this re-attached. If anyone has a suggestion on how to rectify the broken tab I'd really like to hear from you. This system is over complicated for what a heater/air con system has to be. Other manufactures were able to manufacture a simple integrated heater/air con system but BMW and other Euro manufacturers seemed to have missed the boat. Still, it is what it is and repairs have to be made so I'm open to suggestions.

I had a similar problem and posted photos of my solution over on an AC thread on the Bimmer Forum: https://www.bimmerforums.com/forum/show ... st29335914

The plastic pins that stick out and act as hinges were still intact on my flaps but they wouldn't stay in place. I had to attach a clip to hold them in place. It looks like yours are broken off? If so, I seem to remember someone else with that problem epoxying a metal pin in it's place on another thread somewhere.

I've also come to believe that the there is only so much the AC can do without tinting the windows like modern cars. Here in Texas I can get a tan on my left arm driving the BMW in summer.

Correct. Pin is broken off. I thought I might have been lucky and found it in the evap area with the flap. Only found car park ticket and gum wrapper.

Exploring the idea of a ball point pen ink shaft. Its very close to the size and if I shave down one side it should line up properly and attach securely.

masonjones, there's no way I can get the remaining flap out, and I'm certainly not going to force it. Even the broken one will have to have the flap inserted and the pin pushed in and glued. As the opening is just the right size there's no other way to re-assemble.

Will post when a final result is known.

So after a weekend considering all the things I could make a new 'pin' out of I decided to try the ball point pen shaft. I discovered that not all shafts are the same diameter so I took the smallest one possible (2.83mmdia) and notched it so it had a flat edge for alignment and glueing. With the flap in place, I pushed the new pin in from the outside and glued it to the top face of the flap. This gave the best alignment for full movement. I used super glue as it bonds plastics really well, sets quickly and has great durability.

Whilst the result is not pretty, it has been effective. Making sure the super glue didn't stick to me or the outer edge of the flap opening was a challenge but the end result appears to have worked. I needed to use a Stanley knife to remove some excess glue at the edges but the flap works well and should see a few more years of service.

A comment about R134 and it's cooling abilities. I have kept the dealer installed Fridgeking (similar to 70's BMWs) working on my '73 Volvo quite nicely over the years. Recently, after being stored for an extended period of time, I'd found the AC would not cool. This was still running on an R12 charge from 10 years prior. What I did was vacuum the system, let it sit for 3 days to test for leaks (none) and then filled it with RedTek's 12R - a hydrocarbon based refrigerant, just for testing purposes. It worked fine or at least as good as expected and cooled just as nicely as the R12. Just this week I got the 1800ES out of storage, and one year since the refresh the AC is still just as cool. I may just leave it in and forget about the R134a conversion.

And yes, this job would not have been possible without the help of Rob Seigel's AC book - a godsend.

Bhart, here is good ol Australia, R12 is a big no no and we don't have the luxury of going to the local auto or parts store to purchase cans of whatever. Its a very regulated industry we deal with, so R134a is what we have access to.

With regards the ac's in Volvo's, I believe they installed them only to defrost the windows, not to cool the occupants in warmer climates. Even after I gave my 1979 Volvo 242 system a complete once over and regassed (with R134 of course) its operation was barely passable. Still in a big glass house of a car, something was better than nothing.

Before this project started I purchased the necessary TX valve, pressure switch and drier from Pelican Parts.

Now I've come to fit them I find the drier and the pressure switch have different threads. Anyone else experienced this. Seem strange.

Pressure switch P/N 64-53-1-386-971-M325
Drier P/N 64-53-1-466-048-326

So, sorted out the pressure switch by having to re-thread the drier. Not what I was expecting to have to do.

In the end it probably didn't matter as with the R134 gas, a hi/lo pressure switch was needed so this was put into one of the new hoses. It will save the compressor if something goes wrong.

All the lines have been made up, system evacuated and gassed and this project is finished. Cannot say for sure the total effectiveness of all the changes as its only 15deg in Melbourne today but I'll be ready when next summer comes.