Hello All,</P>


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I just bought an 88 300E, and did a tune up. After the tune up, my heater stays on all the time. Through every vent, at max heat. I am not sure where to start, but has anyone else had experience with this? I am wondering if it is a vaccum leak, or a bad control unit? Please help, and feel free to message me!</P>


Thank you!</P>


Mike</P>

 

It must be a stuck heater valve. this is located beside the brake servo. you will see a coolant hose passing through small twin cylinders. call a local dealership and order a new one then fit it this will cure the problem. also check for blown fuses first.