Mercedes-Benz Automatic Climate Control System II Configuration guide

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Mercedes Automatic Climate Control System II:
Installation Manual and General Information
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Before Installation:
-My installation took about two hours to complete.
-Ensure that all fuses are in good condition, and not corroded or knocked out of place.
-You’d be surprised how often a faulty fuse causes the whole system to fail.
-Start the car and cycle through every climate control setting. Make sure any of the issues
present in your automobile are not vacuum leaks. If your climate control system is not
functioning properly as a result of vacuum leaks, this will not solve your problem.
-Before working under the hood, ensure the car has had plenty of time to cool. Make
certain the vehicle is in park with the emergency brake on. Also, disconnect the negative
battery cable to prevent any electric shock or shorts.
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What’s Included
(1) New electronic control unit with five vacuum hoses attached
(1) Heater core “hot water” vacuum valve
(1) Copper tube
(1) 5/8” to 3/4” radiator hose coupler
(2) Hose clamps
(1) 3/4” Diameter radiator hose
(3) Quick-connect cables for servo amplifier bypass
(1) 4-Way vacuum hose connector
(1) 1/8” Vacuum Plug
(4) Plastic cable ties
Helpful/ Necessary Tools
-Phillips screwdriver (multiple sizes and lengths)
-Flat-head screwdriver/ pry tool
-Various pliers (needle-nose, channel locks)
-Socket Set
-Multimeter (optional for testing)
-Gauge to measure vacuum (if the car has a vacuum leak)
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How it Works
-The purpose of the Mercedes Automatic Climate Control II system is for the car to
regulate the fan speed and heater valve positions to maximize the passenger’s comfort,
based on the inputs from the thumbwheel. In the original design, the a/c compressor is
constantly running and is mixed with varying levels of heat to reach the desired
temperature in the cabin. The amplifier-servo setup receives a certain resistance value
based on the car’s three-sensor chain, and then uses that information to determine
whether it is in heating or cooling mode, and the optimal fan speed to balance the desired
temperature with the actual temperature. Although the original design sounds fantastic in
theory, the servo and amplifier are poorly designed parts purchased from Chrysler, and
simply cannot stand the test of time.
-My modern update kit easily integrates into the existing system to maintain the original
controls, and provide OEM function. The central control unit you are about to install
takes the job of both the amplifier and the servo. It uses a modern electronics system to
analyze that same sensor chain, and make real-time calculations to balance the
temperature and fan speed. The central control unit is made up of three solenoid motors
that are able to open and close vents inside the car and the heater valve based on inputs
from the user, just as the original system did. These solenoid motors are designed for
medical-instruments and should last many, many more years.
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Plan for Installation
**Ensure the car is off and cold before working! Also, disconnect the battery.**
-Make note of any vacuum issues before installing the update kit.
1) Remove the glove box to gain access to the amplifier-connector.
2) Following the diagram, install three jumper wires across ports on the amplifier-
connector.
3) Disconnect the vacuum block and wiring harnesses from the servo under the hood.
4) Unscrew the servo from the mounts, and then loosen the cooling hoses from the
bottom four ports.
5) Remove the servo from the car and set it aside.
6) Install the copper tube between the return lines.
7) Install the hot water vacuum valve between the auxiliary water pump and heater core.
8) Cut and insert the source vacuum line.
9) Connect the vacuum line to the hot water vacuum valve.
10) Connect the vacuum hoses from the control unit to the vacuum block removed from
the servo.
11) Connect the old servo wiring harness to the new electronic central control unit.
12) Install cable ties to hold the central control unit to the old bracket/ firewall/
appropriate location.
13) Tidy up and reinstall the battery. Then, crank the car and test for functionality.
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