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Have a '91 190e 2.3 that i have recently acquired. Have searched the postings re: climate control and found some good info. Looking for some insight on where to start. Problem is as follows: no really good heat inside the car with the temp control wheel on max. will blow slightly warm air, then go to cool air..........can not get any temperature out of it to speak of. I reading the threads posted, I'm thinking a possible heater control valve or in car temperature sensor? Any thoughts/experience/help on where to start would be greatly appreciated.

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DA McCord
 

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1988 190E 2.3
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The vehicle getting no heat can be cause by a few things

Low coolant level

Bad heater control valve


Bad vaccum to heater control valve

Pluged Heater core

These cars are also equipped with an axillary water pump



that forces water into the heater core so the heat temp does not cool at idle. If this part fails it is usually accompained by the system completely shuting down when using the heat. (no blower etc)

The first place I would start is with the vaccum to the heater control valve. If your vaccum is good then I would test the control valve this is the only part in the system that is designed to interrupt the coolant flow through the core. The picture below will help you to identify the parts. Just to the left of the blower motor you will see a red vaccum line this is the line going to the control valve that you will need to test for vaccum. In this photo the valve is covered by a foam protector.



The only part that you will have to remove to get to the valve is the cowl screen there is just a few Phillps screws that hold it in place.




Also keep in mind that the mercedes 190's only have heat coming from the right and left of the dash and the floor. The center vents are fresh air or A/C only. Let me know what you find or if you need any further help these systems can seem very complex at first when trying to diagnos a problem.
 

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MTI A good pic is worth a thousand words so they say expectially when it can be used over and over :D
 
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