Klima Bypass Question
 

1986 190d 5 speed, just in time for Fall :goofy:

I am sorry to ad to the already millions of HVAC system posts, but here goes:

I picked up a Bosch standard block/ice cube relay and block. I have decided to bypass the Klima as I can not get the compressor to kick on (see below).
I have been reading up on the various threads on the topic, for example: (http://www.peachparts.com/shopforum/diesel-discussion/230504-klima-relay-deleted-om603.html).

Anyway, I would like to know if someone could put into terms I can understand, where I connect which relay terminal (30, 85, 86, 87 and 87) to which spot on the Klima block (5, 7 and 10). Referencing the below PDF and the above thread, I am not sure how some of the terminology used corresponds with the numbers on the relay. I am an okay auto electrics person, but have only installed aftermarket relays in aftermarket fan setups.

I have just replaced all of the o-rings, installed a new expansion valve, brand new compressor, and flushed the evaporator and condenser with special AC solvent. Also, I replaced the accessory belt and inspected the tensioning system per the MB workshop manual.

Going through the 50 step diagnostic (attached below), I am within spec on everything except high ohms on the speed sensor around 900. Unfortunately, I had the system filled with fresh R12 and am not prepared to waste the money replacing the speed sensor and the refrigerant as I am not confident putting a new speed sensor on the car will remedy the compressor non-start. The PO definitely monkeyed with some of the wiring, 99.9% of which, I restored fastidiously to stock.

I realize there are some pitfalls with eliminating the safeguards provided by the Klima system, but am prepared to live with the consequences of such a conversion.

Thank you in advance.

Michael

With the Klima relay off the socket, look closely at the socket and you'll see the each hole is numbered. Just about all MB electrical connectors have numbered pins and sockets.

Sixto
87 300D

Thanks Sixto. I am not sure I was terribly clear - I know which holes are which on the Klima socket. What I don't know is which corresponding wires on the Bosch relay (30, 85,86 and 87) do I connect to (5, 7 and 10 on the socket. Thanks!

Let's use this diagram to understand what goes on inside a Bosch ice cube relay -

http://www.classictruckshop.com/club...osch/relay.jpg

You want current to flow across 85 and 86 to allow current to flow across 30 and 87. Moving to the Klima, socket 5 has +12V when the engine is running, socket 7 goes to the compressor clutch (needs +12V to engage), socket 10 gets a ground signal from the PBU through the low pressure switch when the system says the compressor should be engaged. Wave the magic want and you should connect 30 and 85 to socket 5, 86 to socket 10 and 87 to socket 7. There might be a convention as to whether 85 is (+) and 86 is (-) but in a floating ground relay like the typical Bosch relay, it doesn't matter.

I use readily available bullet connectors and spread the tip to a snug fit in the Klima socket.

Sixto
87 300D

F'n brilliant. Thanks man!

Just to finish off this thread, I thought I would follow-up with results, a re-cap and some pictures for the record.

AC blows cold and compressor switches on at CCU.

Look on the side of the relay. There are a bunch of pin numbers.

From Brian Carlton http://www.peachparts.com/shopforum/959239-post51.html and Sixto above:

Find pins 30,87,85,and 86.

Connect pin 30 to socket #5 in the Klima plug

Connect pin 87 to socket #7 in the Klima plug

Connect pin 85 to socket #5 in the Klima plug (socket #5 feeds both pin 30 and pin 85)

Connect pin 86 to socket #10 in the Klima plug.

Thanks PP and the people and threads mentioned above.

... more

Keywords: compressor kicking klima ice cube Bosch speed sensor bypass wiring diagram pin out pinout

Anyone have the KLIMA bypass schematic for a HFM W124 (e.g., 124.092) ?

TIA,
:-) neil