Is it normal for the idle to rise to 550 rpm?
Yes 550 rpm is normal. The idle should not rise when AC is switched on. The idle control unit supplies a signal, delayed, to compensate for the additional resistance caused by the compressor. The 116/117 does not have an adjustable idle control. Each component within the system that make up the idle control must be functioning properly.
Can a car idle speed be adjusted without an ICV?
Unless your vehicle was retrofitted with the old idle adjustment valve and ICV removed (pre-84), idle speed cannot be adjusted, only affected by failed componenets. Here are the tests quoted from the MB sevice manual.
How to test a Mercedes-Benz idle control valve?
Plug on couple at idle speed adjuster in a manner that voltage can be measured on plug. Engine at idle. If a faulty control unit is found, nowhere within the Mercedes Manual does it suggest this method but others have suggested this and it worked for me. Remove the control unit cover and lightly twisting from side to side while engine is running.
Is the idle speed adjustable on the Mercedes 116 / 117?
The 116/117 does not have an adjustable idle control. Each component within the system that make up the idle control must be functioning properly. Unless your vehicle was retrofitted with the old idle adjustment valve and ICV removed (pre-84), idle speed cannot be adjusted, only affected by failed componenets.
Yes 550 rpm is normal. The idle should not rise when AC is switched on. The idle control unit supplies a signal, delayed, to compensate for the additional resistance caused by the compressor. The 116/117 does not have an adjustable idle control. Each component within the system that make up the idle control must be functioning properly.
The 116/117 does not have an adjustable idle control. Each component within the system that make up the idle control must be functioning properly. Unless your vehicle was retrofitted with the old idle adjustment valve and ICV removed (pre-84), idle speed cannot be adjusted, only affected by failed componenets.
Plug on couple at idle speed adjuster in a manner that voltage can be measured on plug. Engine at idle. If a faulty control unit is found, nowhere within the Mercedes Manual does it suggest this method but others have suggested this and it worked for me. Remove the control unit cover and lightly twisting from side to side while engine is running.
Unless your vehicle was retrofitted with the old idle adjustment valve and ICV removed (pre-84), idle speed cannot be adjusted, only affected by failed componenets. Here are the tests quoted from the MB sevice manual.