Hello all,
after much research I have not been able to determine the function of pins labeled TD and 87k. Any ideas? This is for a 1987 300TD PN 001 545 80 05.

My compressor was not engaging recently and after following several test procedures I could not find the cause. The compressor would work sometimes and only when cold for about 10 mins and then shut off. No change whether the car was switched on and off.

In any event I went to the pick and pull yard and found a replacement from a gasser. It works fine, the compressor engages when called for and so far no noticeable issues detected. Only thing is that this is a gasser A/C relay and it is missing two pins compared to the original for my diesel. The missing pins are marked TD and 87K on the relay and correspond to sockets # 3 and 6 on the connector.

Any ideas what these lead to and what I'm disabling?
Thanks

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)

TD is the engine RPM signal and 87K I believe is supposed to be the normally closed (not connected) contact of the relay. Doesn't make much sense for the gasser relay to operate without an RPM input. FWIW, the only material diference I am aware of in the function of the relay is that there is an extra cutout switch on the throttle of the diesel. That said I havn't looked at that diagram in quite a while.

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90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE 104.980
Milled & ported head, 10.3:1 compression
197° intake cam w/20° advancer
Tuned CIS ECU
4° ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff

thanks, I wonder if I'm cutting out the extra throttle switch? Here's what the info I've found so far:

GK-/GK+ are compressor speed sensor in and out
87 is the output to the clutch
15 is the power from switched ignition
TD is the engine rpm signal, is this for gas or diesel or both??
The engine speed on my diesel is on GM+
31 is ground
T is temp sensor
KL is the compressor on signal from PBU
87k is kick-down output
VL is full throttle switch

The pin numbers are 1 to 12 with #1 being terminal 31 or the right top end of your list. Pin #2 is GM+. So left to right the numbers are
11, 9, 7, 5, 3, 1
12, 10, 8, 6, 4, 2,

The gas and diesel relays both share the same pin configuration and labeling except for the following:
The gas relay is missing pins 3 and 6 or TD and 87k.
The gas relay also labels pin 2 as TD which is the correct label for the engine speed sensor which on my diesel is on GM+ which is also pin 2. Wheeew that was a mouthful, makes sense though.

So the only one missing on the gas relay is the 87k kick-down output. What does this actually control, the transmission kick-down? Is it supposed to cut out the compressor on kick-down (that would be input right) or is its supposed to do something else?? From looking at the board it does not seem to be tied into anything, but that's a guess without the schematics.

So far the gas relay works like a charm don't know why if wouldn't work for others as well. If the wiring is different on the gasser then why is my relay working so well in a diesel

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Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)

87K: cuts the compressor operation for the duration of its activation.

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mark

Hi Mark,
Thanks for the explaination. So 87k should cutout the compressor when the trans kick-down is activated to improve acceleration I suppose.

So far with a couple of days operation, even the kick-down with the compressor running has not been bad at all.

In summary, if you have a w124 diesel and your A/C (KLIMA) relay causes you problems, a gasser relay from the same generation may be a suitable substitute for you to use without ill effects.

Thanks to all for their input.

__________________
Stable Mates:
1987 300TD 310K mi (Hans)
2008 Jeep Grand Cherokee OM642 165k mi (Benzrokee)