Climate Control Safe Mode - Page 2 - PeachParts Mercedes-Benz Forum

JamesDean · #16 02-20-2014, 11:20 PM

they are also called 'switch over valves'.

They are electrically controlled vacuum switches.

jimandsuzy · #17 02-21-2014, 12:15 AM

Quote:

Originally Posted by crazy4diesel

What's a change over valve, and does my car have them? 83 300TD.

IIRC its function is to keep the idle the same rpm when the ac is turned on i.e. if you didn't have one your idle would drop some when the ac compressor turns on and raise some when the ac compressor goes off. The valve is electrically controlled to add some air or vacuum to the fuel injection unit which causes more fuel to be injected. This answer is worth what you paid for it.

BHutch · #18 02-21-2014, 08:01 AM

On my 85 300sd there is a bank of them on the passenger side behind the center console. They use electrical signals from the CCU to control the vacuum pods. In my case the keg room flap changeover unit was not functioning.

JamesDean · #19 02-21-2014, 10:37 AM

Quote:

Originally Posted by jimandsuzy

IIRC its function is to keep the idle the same rpm when the ac is turned on i.e. if you didn't have one your idle would drop some when the ac compressor turns on and raise some when the ac compressor goes off. The valve is electrically controlled to add some air or vacuum to the fuel injection unit which causes more fuel to be injected. This answer is worth what you paid for it.

On the 617 there is no electronic influence over the idle speed.

The switch over valves referenced in this thread are for controlling the various vacuum pods for the HVAC system.

In the 84/85 617 cars there is a microswitch on the top of the valve cover that will cut out the a/c when it is hit.

I believe you are thinking of the idle air control valve and the idle control system that is found in the gasoline powered cars. On there 617 diesel there is no equivalent that I am aware of.