The Temp Control on my 1987 560SL has stop working. It did work but was very slow to change temp when moving switch. Now it only blows cold air no mattter where you set temp. Could use some help. thanks

 

Steve, what happens when you turn the wheel to heat-MAX(make sure it 'click's all the way into MAX setting). Also, What happens when you push the defrost button?

 

SunGuy62

The heater worked fine per your instructions. Do you have to do this each time to use heater? Is there something wrong with the system?
Thanks
Steve

 

Steve,
The problem with your system is the monovalve has gone bad. You will need to buy a monovalve solenoid repair kit from (pick your favorite online parts supplier) for around $40 for the Bosch OEM valve. The monovalve housing is installed on the passenger/right side firewall; you'll see it if you follow the water and electrical lines into the housing. The old monovalve solenoid unscrews and removed; reverse the steps to install the new one.

The 117 engines seem to eat these things and I replaced 5 of them over the 10 years I owned my '87. For more information or to clarify anything I've said, use the search tool in the 107/SL forum using the search term 'monovalve'. You'll get a ton of info that will help you.

Bob

 

SUN GUY 62

Thanks very much for the info. I'll go to Car Quest Tuesday, they handle Work Pak Merceds parts. Thanks again.
Steve

 

Your welcome. I think you mean WorldPac. Check the pricing, you should not be paying over $40 to $45 for the monovalve. If they charge you more, you can order one from Auto Parts at AutohausAZ - OEM Auto Parts - Discount Replacement Parts, Resources and Car Care Tips . Very reliable supplier, ships quickly, w/free shipping to your door for orders over $50.

Bob

 

SUN GUY 62

I got the mono-valve yesterday, put in this morning and heater works fine. The rubber bellows on bottom of valve was rotted out. I got one from from Car Quest who owns World PAK. They deliver twice a day from MA to Portland, Me so only waited about 4 hrs. Did cost $54 but Borsch Brand.
Thanks again for all your help.
Steve