Climate control upgrade - PeachParts Mercedes-Benz Forum

kahlil88 · #1 06-23-2012, 02:50 AM

I'd like to upgrade the climate control in my 1978 300D. The car currently has the big York AC unit, which came zip-tied and without belts when I got the car. My friend has a 1981 300D for parts that must be towed soon. This is probably way over my head, but it would be nice to know what is involved.

charmalu · #2 06-23-2012, 11:21 AM

Doesn`t the 81 still have the Evil ervo like your 78? Or are you thinking of swapping in a R-4 compressor? the 81 was changed to that, right?

How exactly did you wanty to up grade it?

Charlie

kahlil88 · #3 06-23-2012, 03:09 PM

Am I correct in my understanding that the servo is for heat and the compressor is for cold air? I haven't been able to get either working, but this might also be related to my vacuum system in addition to the York being beltless and zip-tied. The wiper fluid squirt, door locks and shutoff have never worked. Not sure where the servo is or what it looks like, but if it's identical I see no reason to replace it unless mine turns out to be defective. I have pictures of both cars' engine compartments, just click link for the '78 in my signature, and here is the '81 Mercedes 300D parts car.

cfh · #4 06-23-2012, 10:06 PM

My coupe had the evil servo that went kaput; swapped in a manual system from a 240d and am very pleased. Better if you have the parts car; there are differences in the wiring harnesses, connectors, etc. I did a complete swap and added sound deadening when the cabinet and dash were out. It took a few weekends and I drove around with it looking like something out of mad max for a while with the guts all exposed and the instrument cluster just jammed up there. Better see it through when you get to that stage!

vstech · #5 06-24-2012, 12:59 AM

the R4 will not bolt up to your block... no mounting holes for it.

you could swap in the entire engine... get the updated glow plug system as well...

and the 81 has the typeIII a/c system in it... no servo, your car has the servo, behind the passenger's headlight. odds are VERY good, yours is broken.

cfh · #6 06-24-2012, 01:19 AM

I've read somewhere that there is a bracket available for replacing the york compressor with a sanden which is supposed to be much more efficient.

charmalu · #7 06-24-2012, 01:26 AM

The 78 has the Servo, it is under the air intake hose and has that bundle of vacuum hoses going to it. the buttons on the dash will be in a verticle set up. and has the York AC Compressor.

The 81 has the Mono valve on the firewall to the right of the battery tray. there is suppose to be a valve that set inside it that controls the water flow to the heater core. the PBU (push button unit) on the dash has the horizonal buttons. the AC compressor is the R-4 that is mounted on the lower left of the engine. the large hose coming from under the battery tray and across the front of the Valve cover will lead you to it. this is one of the AC hoses.

I may be wrong, but don`t believe the R-4 compressor will bolt onto the 78 engine. there may not be the mountings cast on the block for the AC mount bracket.

I was looking at your 83, looks like a Euro, and has the manual climate control system. this is what CFH was mentioning he installed into his. the best system of the three.

MB refers the manual as the type one
The servo as Type two
The one with the Mono valve as Type three

As per the FSM.

If you want to do any swapping of systems, go to PNP and remove the dash and the whole heater/AC box from a 240D. you are looking at around $60+ for one. you will have the Blower, Heater Core and Evaporator. take the box apart, clean the evaporator fins of debris, and the Heater Core. replace the old dry foam seals on the various doors, and you will be good to go.

I have one apart now, and hope to have it in by winter.

Charlie

kerry · #8 06-24-2012, 10:21 AM

You have vacuum problems. Without vacuum the servo will default to defrost and do nothing else. Before deciding whether to upgrade your climate control you need to fix the vacuum problems to determine if your current system is functional or not. If it is, fixing the York compressor will get you AC.

kahlil88 · #9 12-21-2012, 02:52 PM

Sorry I took so long to post back! Sold this car to my friend about 6 months ago so it hasn't been a priority, but now that winter's here I'd like to figure this out so he doesn't freeze!

Quote:

Originally Posted by kerry

You have vacuum problems. Without vacuum the servo will default to defrost and do nothing else. Before deciding whether to upgrade your climate control you need to fix the vacuum problems to determine if your current system is functional or not. If it is, fixing the York compressor will get you AC.

Very true, probably best not to complicate things by trying to convert the entire system, parts car was towed ages ago anyway. I guess what I need is a starting point...I know the York A/C doesn't have a belt, but I'm not sure what size it needs and once that's in how to go about testing it.

Quote:

Originally Posted by cfh

I've read somewhere that there is a bracket available for replacing the york compressor with a sanden which is supposed to be much more efficient.

I had a look at the Sanden retrofit thread...definitely want to give it a shot eventually, since it sounds like the York really drains horsepower. Once I get the system working, of course.

Quote:

Originally Posted by charmalu

I was looking at your 83, looks like a Euro, and has the manual climate control system. this is what CFH was mentioning he installed into his. the best system of the three.

MB refers the manual as the type one
The servo as Type two
The one with the Mono valve as Type three

Thanks for the info, my Euro never had climate control problems. All the more reason to hang onto it, despite the ugly rear-end damage...