I have W126 350SDL

As said it's running all time but I have heat inside the cabin. but rear vent blowing cold air. I noticed today when open hood to check fluids, and saw air conditioner pipe has frost. I put on eco mode and still frost there.
Is any relay ? Any idea?

Thanks

The rear vent only blows whatever the intake air source is (recirc or fresh air). It doesn't blow conditioned air from the heater core or evaporator. If you have the heat on, it'll feel cooler than what's coming out the front vents.

If you're in EC mode, the compressor shouldn't be running. See if the center hub of the compressor is running. If it is, the KLIMA relay is probably toast. Worth repairing/replacing since it can destroy the compressor.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

KLIMA relay?
Location?

The AC clutch engagement is completed with a ground. It normally has battery voltage at the clutch and when operation is commanded the ground side is closed to complete the circuit. I had the issue of the compressor running sometimes when it wasn't supposed to. Found it to be the ground signal wire had not been properly secured during a compressor changeout, and it got wedged in between the compressor and the bracket where it got pinched enough to complete the ground side of the circuit and engage the clutch. The wire is black. This was on my w124 but I don't see why yours would be different, check the wiring.

If I recall the Klima on mine is in a compartment behind the battery.

__________________
Brian
87 300Dturbo 180K #14 head still running R-12 SOLD 12/2017
02 F350 Powerstroke 180K
05 Chevy Express 1 ton w/Royal Utility box 120K
08 Infiniti FX-35 40K
15 Golf Sportwagen TDI 35K
10 Sprinter 3500 chassis with a Class A Winnebago on it. 56K

Pull a wire from the low pressure switch behind the driver side headlight. Either wire on the switch without pigtails. If the compressor stops, the problem is in the PBU. If the compressor doesn’t stop, the problem is at the Klima relay or downstream.

Sixto
98 E320s sedan and wagon

I looked behind engine compartment to find Klima and found this :



Removed one of ends and air cond stop working. I read that some 350 SDL cake with another electronic unit that do same job as KLIMA. But I have engine from 1987 SDL, that might had different wiring / harness. Is it true late 350 SDL has another electronic unit (MAS)?

I guess I have to buy relay and try on.

Is anyone wanted to sell me an extra one ?

__________________
91' MB 350 SDL, with 961 engine and #14 valve head
09' ML320 Bluetec

Well that would be an issue for sure. My KLIMA failed with the relay stuck closed and turned the compressor into a pile of scored and melted aluminum when the refrigerant leaked out.

There is no MAS on a 350SDL, the MAS is for the gas engined vehicles.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Thanks. Any idea part number for the relay?
Pelican part don't show me any relay for this 1991 model.

I need a favor from people who own 1991 SD or SDL, take look under hood for the KLIMA part number please.

Thank you

__________________
91' MB 350 SDL, with 961 engine and #14 valve head
09' ML320 Bluetec

A Klima relay from any W126 should work. The 90/91 SDL's use the same pinouts as the 86/87 does with the exception of the kickdown switch and the overtemp switch. The 90/91 has no connection on those pins since the kickdown was re-routed in the late 80s and the overtemp function was built into the ACC.

The part number on the KAE relay I bought for my SDL is 3.701.100 If you Google that part number, you'll find a huge number of listings out there with highly variable prices.

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

Thanks

__________________
91' MB 350 SDL, with 961 engine and #14 valve head
09' ML320 Bluetec

When I was buying this I don't see this jump, it hidden very well. I looked online apparently relays for W124 300E series (003-545-56-05) has exactly same pin out as 350 SDL.
Is anyone has W124 diesel, and can you check your part number for Klima relay?

__________________
91' MB 350 SDL, with 961 engine and #14 valve head
09' ML320 Bluetec