A/C Install

[George Des]

After going through all the trials and tribulations of trying to use the original compressor bracket off a 280Sl, I've finally decided to cry uncle and go to the top mounted system like some of you guys have. I had the system all set up and it was really pumping some good cold air, but after a while I started to get this terrible screeching from my alternator/compressor/water pump/fan belt.

When I took a better look, I could see that the belt was slipping on the water pump--not a good thing and a real recipe for overheating. I tried fitting a number of different size belts and styles (notched, etc) and did no better. When I thought more about it, I came to see this as a real weak link and single point of failure for this set up.

With the top mounted compressor you guys are using, if you have a compressor clutch freezeup, or the a/c belt breaks, it does not take down the whole system-not to mention how much easier it is to disconnect the whole a/c system or change a belt if you need do so. So I've decided to use the Bud's Benz type a/c bracket--I was fortunate enough to come by one off a wreck a while ago and had it sitting around. What I don't have though is the fitting that goes to the thermostat housing from the FI.

George D--I noticed that you mentioned this in your post on another forum and had found another way to do it by making a hollow banjo bolt or something, could you elaborate on this and any other install tips regarding the bracket e.g. use of spacers, any other support behind the compressor etc. Does nayone know where I could get just this fitting ?

Thanks--George Des

[n/a]

Hi George

The trials and tribulations of having cool air in a 113! I take your point about having a top mounted compressor however this setup is not without complications either. As you have noted, keeping the air con and cooling belts separate is a definate advantage. I have found however that the compressor makes access very limited. Tightening the fan belt from above becomes a major operation and most easily done by removing the top end of the lower radiator hose. This is not exactly convenient. Also, the alternator can only be reached from below making it necessary to put the car on a hoist to work on it. In fact, the last time I broke a fan belt the car had to be towed to a workshop. I had a spare belt but it was not possible to change it on the side of the road. I have replaced air con drive belts three times in the past 12 months. This is not that difficult but you have to remove the power steering belt to get to the crankshaft pulley. My car has broken down (or failed to proceed) only twice since I've owned it. Both times can be attributed to the air con system. I'm chasing up some alternatives to overcome the breaking belts at the moment. I've been told that a taller profile thermostat housing will raise the top radiator hose sufficiently to eliminate an idler pulley which appears to be the culprit. I'll get to it eventually but now that it's autumn I'll probably put it on the back burner.

The irony is that the previous owner went to considerable expense to have the air conditioning fitted to the car not long before I bought it. She complained that the car was getting too hot inside. The cause turned out to be a broken air flap in the heater which took me five minutes to fix with some Araldite. I don't want to discourage you but this has been my experience. I'd be interested to know about the experiences other list members have had with retro fitted air.

Mark

1965 230 SL light blue, auto, RHD

[George Davis]

Hello George,

The Bud's Benz kit is fully installed in my car and working now.  It is not super cold (using R-134a) which is a little disappointing, but I think it's cold enough to do the job.  No belt failures yet, I'll keep my hopes up.  Yes, it's a tight fit when it's all in.

The fitting you are interested in, as supplied by Bud's, is in my opinion junk.  It's just two brass fittings screwed together, with the threads ground off one end so a hose can be clamped on.  I made a longer banjo bolt by hollowing out and cross-drilling a bolt with the same threads as the original.  A spacer is then needed behind the banjo fitting to move it out far enough to clear the bracket, plus three sealing washers.  I suggest cross-drilling the bolt before hollowing it out, I did it the other way and the drill bit really catches trying to go through the inner curved surface.  The pipe on the banjo fitting had to be rebent a little bit to clear, too.

The spacers behind the bracket were all labeled for location, but I'd guess they are fairly intuitive.  I considered welding them on, which would probably be ok, but to keep them flexible in case of misalignment, I simply ran a fat bead of RTV around each one to hold them in place.  That worked nicely.  I didn't RTV the top spacer in case I wanted to remove the FI line bracket in the future.

I replaced some of the bolts in the kit.  There is one large hex bolt that ends up very close to one of the belts.  I replaced that bolt with a button-head bolt to minimize possible belt damage from contacting the bolt head.  I also had to countersink and replace two other bolts with flat-head allen bolts because they interfered with the water pump pulley; might not be a problem on a 230 SL, though.

The kit included a bracket for the rear of the compressor, don't know if you have that.  It's made from a piece of 1x1 angle iron, cut to clear and drilled to match one hole on the compressor and one of the studs on the thermostat housing.  The instructions say to grind the little nipple off the t-stat housing for clearance, but it's just as easy to file the angle iron to clear.  I can photograph it if you like.

The idle air screw has to be relocated slightly, you'll see when you fit the compressor.

That's all I can think of right now.  Let me know if you'd like a photo.

George Davis
'69 280 SL Euro manual

[n/a]

Slightly off topic.
About 10 years ago I installed the Bud's Benz AC kit and from day 1 I was never really satisfied with the cooling capacity. After 3 years I just removed the AC belt and never used that system again.

Now I am nearing the end of a total interior restoration, and have fully removed my AC system. I am debating what to do here:
1) leave it off
2) clean everything, new seals, charge w R22 and hope for best
3) #2 plus replace my expansion valve, fill with R134a
4) #3 plus add an extra condenser coil

I have seen some original SLs w an auxillary under bumper AC condenser, so me thinks even 30 years ago there were some unhappy hot owners. Anybody done this? Where to find parts? How bout 134A conversion (i know this reduces cooling and generally requires extra consenser area)?



Mike McMahon, Baltimore MD
1970 280SL 4-speed manual
olive green ext, bamboo int

[George Davis]

George Des:

The photo shows the rear compressor bracket.  I had the size wrong, it's more like 1x2 angle iron.  Slightly relocated idle air valve shown, too.  Hope this is useful.  (Note clever use of old sock to provide contrasting background!)

Download Attachment: AcRearBracket.JPG
65.99 KB

George Davis
'69 280 SL Euro manual

[George Des]

George--thanks for the photo--that really helps. I don not have this piece but should now be able to fabricate one faily easily. the banjo bolt part is alos interesting and if possible I'd like to try this route out myself. i really don't want to cut that pipe in case I later decide I want to go bak to the ways things were. Could you tell me how you managed to drill the bolt out so precisely and then cross-drill it.

<Mark--I looked at your setup and recall you had a problem with it chewing up belts--atributable to the idler running on top of the belt. You may want to consider eliminating this pulley and mounting your other pulley on an eccentric so you can make the necessary tensioning adjustments to the blet. This is how the Bud's type setup works and there is no second idler as in yours. Just a suggestion>>

George

Thanks --George

[George Davis]

George,

I'm glad the pic is useful.  The pipe on the banjo fitting doesn't have to be cut, the bends just have to opened up a bit to clear.  Alternatively, you might be able to notch the main mounting bracket, I didn't think of that at the time.

For drilling out the bolt a lathe was used, but I think a drill press and machinist's vise would work, too.  Lathe was useful for the spacer, too.  If these prove problematic, give me a shout and maybe I can help.

George Davis
'69 280 SL Euro manual

[George Des]

George D,

Notching the bracket was also my first thought, but I wondered if that would affect the rigidity of the bracket itself. Perhaps not with the extra support you photoed behind the compressor. I may look further into going this route but the help on the hollow bolt is greatly appreciated.

George Des