1983 Mercedes Benz 300td Heater issues

Tiny
SSAVVY
  • MEMBER
  • 1983 MERCEDES BENZ 300TD
  • 5 CYL
  • TURBO
  • RWD
  • AUTOMATIC
  • 155,000 MILES
I am having issues with getting good heat sometimes I get good heat and other times I get cool air when I start the car and when I am driving and getting good heat it can change and blow cool air. I replaced the mono valve and now the temperature is going sky high and there is no circulation from the anti freeze could the problem be the aux water pump?
Tuesday, November 26th, 2013 AT 2:24 PM

4 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
I never heard the term, "Mono Valve". Can you explain exactly what that part is? I most likely know it as another term.
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Wednesday, November 27th, 2013 AT 9:34 AM
Tiny
SSAVVY
  • MEMBER
  • 3 POSTS
Mono valve is also called a Heater Control Valve.
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Wednesday, November 27th, 2013 AT 1:37 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Okay, that makes sense to me. Do this for me. Start the engine, let it warm up with the heater on high. Feel both heater core hoses and tell me if both are hot or if one is hot and one cool.
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Wednesday, November 27th, 2013 AT 4:42 PM
Tiny
DR LOOT
  • MECHANIC
  • 2,311 POSTS
Sounds like the circulation pump located in the front right fender, right above the receiver drier, make sure you are getting power to it and check for vacuum leaks.
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Sunday, February 15th, 2015 AT 7:50 AM

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