Buds Benz Air Con Kit

[DavidBrough]

I am considering fitting the air con kit supplied by Buds Benz and would like to hear from anyone who has experience of this system.

Is it straight forward to fit and what is the quality and performance like. Also, my car has never had A/C fitted before and I do wonder if I will need to replace or upgrade anything else or is everything required provided in the kit. I seem to remember reading somewhere that A/C cars had different water pumps to allow for the fitting of a wider pulley. I already have a three core radiator and additional fan which should negate any overheating issues. Any comments gratefully received.


David Brough
280 SL Auto

[George Davis]

David,

I have the Bud's Benz air con kit, and am generally happy with it.  The underdash unit is not as nice as the Frigiking, but in my car's black interior it blends in fairly well.  Performance is good enough to do the job with the fan on speed 2 out of 3 most of the time.  It's a bit noisy because of the fans.

Realize that you'll need to make two (or one, maybe) hole in the floor for the condensate drain tubes.  I actually drilled through one of the transmission support bolts and ran a single drain through there.  It's a small tube so doesn't drain as well as one might like, but it works.

The kit includes all the parts, but I felt many could be improved upon, so customized things a bit.  Took me maybe 4 weeks altogether.

Unfortunately, must run now, but will try to post more later.  Do a search on air conditioning and look for my names as well as George Des, we discussed things a year or two ago.

George Davis
'69 280 SL Euro manual

[DavidBrough]

Thanks George, I would be interested to learn more about the parts you modified when you get time.

David Brough
1969 280Sl Auto

[George Davis]

Hi David,

next installment:

The kit includes a large mounting plate that mounts to the front of the engine and surrounds the water pump and the bent coolant pipe that comes off the front.  The bent coolant pipe is attached by a banjo bolt, which can't fit with the new mounting plate.  The kit includes a small (and very cheesy, IMO) hose fitting to replace the bent pipe and banjo.  A better solution is a longer banjo bolt.  In my case, I made one from a bolt, but it may be possible to find an appropriately sized double banjo bolt.  The longer banjo bolt, plus a spacer ring, moves the bent pipe out in front of the mounting plate; after that, just a slight bit of rebending of the pipe and it fits as before.

Regarding the mounting plate, after figuring out where everything goes, I decided some of it could be cut off, I think on the left side as you face the engine.  I think this was done mainly to improve access to the head of the bolt that secures the idler pulley.

One of the bolts in the kit ends up too close to the belt for comfort, so I replaced that hex-head bolt with a button-head cap screw.

In an effort to get best cooling performance, I replaced the condenser in the kit with a parallel flow condenser that I got at a local radiator & a/c shop.  I also got a mounting kit from them, because I don't like those plastic, through-the-fins mounts.

I think the kit directions tell you to tap into one of the existing circuits and fuses.  I decided instead to run a wire directly from the battery, through an in-line fuse, to a relay.  The relay is activated by the a/c unit, so the relay handles all the power instead of the a/c switch and all those old wires.

The directions for mounting the underdash unit say to run a screw up through the underdash pads and into the dash sheet metal.  I'll have to see if I have a pic of what I did, because it's a bit difficult to describe, but basically it avoids drilling through the pads and dash.

I believe I ended up getting a different size belt to get better belt routing.

There is a small bracket that supports the rear of the compressor, it bolts to one of the thermostat bolts.  Kit directions say to grind a little pip off the thermostat housing, but it's just as easy to file the bracket a bit to miss the pip.

The control knobs that come in the kit are cheesy, too.  Becker radio knobs drilled out slightly can replace them, they look much better.

Anyway, those are most of the changes.  Sounds like I'm really knocking the kit, but I don't mean to.  It has most of what you need, but a few improvements are possible.

When on, the compressor pulls idle speed down about 100 rpm.  The car doesn't have a constant speed solenoid, so I compensate by turning the idle up a bit.

If you don't know for sure that your water pump is fairly new, then you might want to replace it while you're installing the kit.  Removing the hood and radiator is just about mandatory for the job.

I'll look for some pics and post if I find them.

George Davis
'69 280 SL Euro manual

[DavidBrough]

Thanks George, excellent information. Would like to see the pics if can find them.


David Brough
280SL Auto

[George Des]

David,

As George Davis said-there is a lot of info posted on this subject as we had both gone down a pretty similar path with the A/C systems. Where george used a Bud Benz underdash unit, I opted to use the original Kuhlmeister unit, but from there on forward under the hood, George and I have pretty much the same set-up with a rotary compressor (Sanden 508) mounted on a flat plate bracket with an idler pulley and a parallel flow condenser. I did upgrade to a SPAL blower unit whcih mounts directly to the KM evaporator box. When the system is on, there is virtually no drop in engine RPMs with the Sanden compressor and witht he hartop on, the system gives more than adequate cooling. I do have somewhat of an engine heating issue when idling for long periods with the A/C on--the reading goes up slighlty higher than normal but still well below the red area--I attribute this to the decreased radiator cooling area because of the size condenser I've used, so I may go back and try a slightly smaller one at some point. There are several options to the compressor mounting. Like I said, I've got the flat plate one that I copied off a Bud's Benz original. George pointed out the issue on the cooling fitting--Like George, I did not have the heart to cut this pipe and use a fitting as prescribed. Instead I cut a slot in the bracket. I also have on-hand the dealer bracket used to mount the original and I tried this but ran into too many pulley issues--I have a 230SL and the arrangement is slightly different from a 280SL. I've recently come across an A/C compressor bracket used on a 280SE of that same era and I may at some point look at trying this out as well. I'll do this to get a more factory look to the mounting and to sort out soem belt issues caused by where I located the idler assembly on my Bud's "take-off" bracket.

George Des

[graphic66]

Make sure when mounting the condenser your hood will open and close without hitting anything.

[AGT]

David

Stefano Mazzoni at Merparts in Port Glasgow repaired/renewed the air con in my 280SL last year. My ex Californian car had the FrigiKing dealer fit system which was completely gunked up. I wanted to keep the FrigiKing underdash unit but replace all other components.

I got the Bud's kit without the underdash unit - i.e. - compressor, mounting bracket, condensor, hoses and receiver/drier. Stef got it all to fit but I would say (and it wasn't my knuckles that got sacrificed) that it is a very tight fit.

With the SPAL blower mentioned in other posts and the re-conditioned evaporator box, the system is very efficient although the icy blast is directed at the passenger - unless you fancy trying the additional piping per the SL Tech modified system which brings an air supply round to the driver's footwell.

No trouble with overheating although I had not really been worried about that in cool Caledonia and both the radiator and water pump were replaced when the a/c was installed.

Give Stef a call and he will talk you through the project and the good and bad points of the Bud's kit. One obvious upgrade from the Bud's kit is a receiver/drier with a high/low pressure cut off to protect the system.

Merparts is listed at page 14 of the April 2007 M-B Club Directory or e-mail me off line for Stef's contact details.

Regards
Andrew

[DavidBrough]

Thanks guys, very useful information. As a result I’ve decide to take advantage of the favorable exchange rate and ordered the Buds kit on Friday. I’m not really sure what condensers, driers and compressors do in A/C systems but I think I’m about to find out.

As I will have to remove my radiator again I am considering replacing the standard viscous fan with an electric one after seeing the recent post about our German friends using a 16” slim line Spal fan. Has anyone tried this?

I have spoken to the UK Spal importer who felt that this fan may not be up to the job when used with my 3 core radiator as it only has a free airflow of 1610 cfm. Does anyone know the performance figures for the standard fan?

Thanks


David Brough
1969 280SL Auto

[George Des]

David,

Actually an A/C system is pretty simple. It works on the principle that an evaporating liquid absorbs heat. The liquid in this case is the refrigerant--either R-12 or R-134A. The condensor sits in front of the radiator. This can be a tube and fin matrix or a parallel flow matirx. The parallel flow condensors have more exposed surface area to the air flow and are more efficient with the newer refrigerants such as R-134A. The condensor's purpose is to expose the heated refrigerant to ambient air flow where it can give up most of the heat it absorbs when flowing through the evaporator which is a copper or aluminum finned matrix that sits in the underdash box in front of the blower fan. The blower fan drives the air across the evaporator and the liquid refrigerant, while absorbing the heat from this flow, turns into a gas. This provides the cooling effect in the passenger compartment. The cooling also removes humidity from the air flow and this is what causes condensation to form on the evaporator--this condensate must be let out of the evaporator box via a drainage tube through the floorboard. The heated gas, in addition to having to give up its heat via the condensor, must also be compressed before it is sent through the condensor and turned back into a liquid--this is the purpose of the compressor.. The drier has two purposes; first it contains a dessicant or drying agent to ensure the refrigerant contains no moisture--moisture if present can cause all sorts of problems with freezing in the small passages of the expansion valve which sits on the inlet side of the evaporator--not to mention the damage it can do to the internals of the compressor. Second, the dryer also serves as a refrigerant reservoir. All this sounds pretty complicated in words, but the system on our cars actually has very few complicated parts unless you get into a full climate control system as on modern cars. Hope this all helps.

George Des

[DavidBrough]

Thanks George, Great information. I always think it's good to know how something works when you come to fit it although I may have to read your post a few more times.


David Brough
1969 280SL

[graphic66]

Finally got around to charging my Buds Benz system with some R-12. I had filled it with 134a using a converted filling hose, 134a can, R-12 filling end and it cooled just OK. I put the refrigeration vacuum pump on the system for about one hour, then put in 2 cans of the rare and expensive, [$20.00 per can at a parts store in TN ] R-12 in the system. Wow, what a difference, it really cools now. You need to turn it down after cruising a while with the ragtop up. It works way better with R-12.

[saygold]

A follow-up question: I installed a Buds Benz unit for my 1966 230SL a number of years ago.  I did not install the 3 cover pieces under the dashboard because I thought two of them would have to be altered to fit behind the air conditioning unit, and I was in a hurry to drive it.

Now I want to re-install the cover pieces to reduce the noise from the engine compartment when the top is installed (I should have done it the first time).  Will these pieces fit or should I make my own?

Thanks,

Ken

'66 230SL euro, 4-speed

[68_white]

I would interested in knowing if your fingers get cought on the underdash unit when you turn the window crank.

I saw two of the BUD's A/C units that would scape your fingures every time.



HARRY

68_WHITE

[DavidBrough]

Well the Buds kit has arrived and battle commenced.

The compressor fitting seems to have gone well only requiring some slight easing of the mounting bracket holes. I must admit to being quite surprised at the size of the condensing radiator and I will have to remove my auxiliary electric fan to fit it. This is not so good as even without A/C I need it to keep cool whilst stationary. I think I will try a SPAL fan to replace the standard viscous unit and may also try the heater bypass trick.

In looking at the under dash unit It seems this will require moving the bonnet/hood release and also require some cutting out of the passenger kick plate side panel, as this does not have the same cut outs as the right hand side, to accommodate the refrigerant lines.

Will keep you advised of progress but, in the meantime, if anyone has a picture of the fire wall entry point for the refrigerant lines this would be most helpful.

I will have a look at the window crank and re fitting the trim for Harry and Ken when I get there.



David Brough
1969 280SL Auto nearly with A/C

[DavidBrough]

After a few days break in the Lake District, it rained, battle has recommenced and most of the Buds kit is now nailed in place. Overall, it seems that it takes about a day to install after 3 or 4 days of cutting grinding balancing guessing and drilling all with firmly crossed fingers. I am now down to the last bit, mounting the dryer and am looking at placing it on the right drivers side of the fire wall between the hood/bonnet catch and the heater outlet pipe. I would be keen to know where others have mounted it and if this is felt to be the best place.


David Brough
1969 280SL Auto (now quite close to having A/C)

[DavidBrough]

Hi Harry,

You are right about the window winder; it will scrape your fingers if you are not careful. I must thank you for your comment though as it did make me check the winder did not touch the A/C unit before mounting as it could easily do so and make opening the window only possible with the door open.

David Brough
1969 280Sl Auto


Download Attachment: A-C Unit.jpg
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[Raymond]

Graphic 66, I hope you changed the compressor oil when you went from R-134 to R-12 as they are different and will affect the life of your compressor.

George, I put on a Sanden 508 as well and, using the factory bracket, the pulleys didn't line up.  I found spacers at the Lowes and with slightly longer mounting bolts, the pulleys line up perfectly.

Ray
'68 280SL 4-spd Coupe

[Naj ✝︎]

quote:Originally posted by DavidBrough

 I am now down to the last bit, mounting the dryer and am looking at placing it on the right drivers side of the fire wall between the hood/bonnet catch and the heater outlet pipe. I would be keen to know where others have mounted it and if this is felt to be the best place.


David Brough
1969 280SL Auto (now quite close to having A/C)

This any help??



naj

68 280SL

[DavidBrough]

Success. Just had the Buds A/C system gassed up and it works a treat, well so far at least. All I need to do now is keep the engine bay as cool as the interior.

Whilst fitting the A/C I also fitted a heater bypass hose using two T connectors and a length of hose running over the head. This seems to keep the engine a little cooler and the heater still gets hot, although how it will work in winter remains to be seen.

I’ve also ordered a SPAL electric fan which I will fit in place of the standard viscous unit but that won’t be here until early August so I will see how the standard fan and heater bypass set up performs in the meantime. Will let you know how I get on.

Thanks for the photo Naj. With the hose lengths I had the dryer ended up by the gearbox filler neck.


David Brough
1969 280Sl Auto now with A/C