Early W126 Klima Heater Control Monovalve Conversion without Heated Windshield Washer Fluid Tank

Free Performance Kit Included. For most 126 sedans and coupes 1981 through 1985. Replaces the original Bosch valve on ACCIII U.S. Automatic Climate Control cars - Limited Stock

PLEASE NOTE In stock now and ready to ship. No detailed instructions at this time, but it is not a difficult install this unit once you remove the false firewall at the back of the engine. You will be able to gain access to the monovalve and electric pump assembly. There is lots of information on the internet that can help you with installation. Just google " Mercedes W126 monovalve replacement." We do include some instructions on installing the black hose and fuse holder, but those instructions are specific to the W123 and R107. The same principles apply just location and pictures are different. 

Early W126 Klima Heater Control Monovalve Conversion without Heated Windshield Washer Fluid Tank
Free Add-Ons Included:

How to Install our ACCIII Climate Control Performance Upgrade - On Demand Video

Product Details

watch road test results in a 380SL

This is probably the very best upgrade you can make for your early 126 automatic climate control. It will switch the hot to cold or cold to hot much faster and will hold a much steadier heat at high engine speeds. The original heater valves are old and they are tired. Even the newest model is now 30 years old. If you own one of these cars, you might agree that your systems “works” most of the time but sometimes, not so good. In the past, you probably replaced the mono valve and things improved. At least you were getting hot when you wanted it and could turn it off when you desired. But now you find out that Bosch is no longer making the mono valve replacement and your system is acting up again. This valve is the HEART of the system. If it is damaged or not working properly then you will never get the heater to work right. Bosch monovalves and monovalve repair kits are now no longer available new. Many aftermarket rebuild kits are notorious for poor quality. Even after rebuilding, the OE Bosch monovalves tend to operate poorly at high RPMs and are prone to sticking. Klima Design Works BV Series valves are a new and superior replacement heater control valve system that uses technology from late-model vehicles.

We include a bonus kit that will increase the longevity and performance of your system. Many don't realize there is a rotten deteriorated foam hose that has fallen off your center dash temperature sensor thus making the sensor "confused." Many also do not realize an overloaded aux. water pump can damage your climate control panel. Many don't realize the aux. water pump is not even working and can lead to poor heater performance. (It is better to remove it all together than to leave it installed when it won't pump! You will receive a replacement hose and fuse with complete video instructions.

WARNING: Keep in mind this valve may not fix all your heater issues. You must also have the following:

  • 1. A good working auxiliary electric water pump ( replace or remove it from the system at best )
  • 2. Non deteriorated temperature sensor foam hose under your dash ( replace it with our kit)
  • 3. Good working heater blower motor
  • 4. Properly functioning climate control push-button panel
  • 5. Properly functioning temperature logic box ( located under dash behind glove box)

It may take some work on your part to troubleshoot additional problems with your system. Since it is the “heart” of the system replacing the monovalve is the best place to start. It is almost impossible to troubleshoot other problems unless you first know you have a good working valve assembly. 

IMPORTANT! If you are not sure if your W126 has or does not have heated windshield washer fluid open the hood and take a look at the white fluid tank. If there are no tubes coming in the top of the tank then you don’t have heated fluid. If you see a couple of bent stainless tubes going in the top then you do have heated fluid!

Here is a picture of your heater valve assembly located behind your false firewall with the Klima unit alongside it. You can see once you get to it you can remove the old monovalve assembly from the hoses, stick the new Klima unit in and tighten the clamps. Be sue to remove about one gallon of coolant from the radiator before opening up the hoses. Even then you will experience some  coolant loss so be prepared. 

If you want the best way to test your current monovalve or electrical water pump get our 12 volt power probe tester. See related products below:

We highly recommend you replace your old Bosch electric coolant pump with the newer Bosch pump used in many of the 1990 and early 2000 models. This pump will increase the reliability and performance of your climate control system. We offer a complete conversion kit. See the related products below:

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