1991 Mercedes Benz 300se

1991 MERCEDES BENZ 300SE
12,000 MILES • 6 CYL • 2WD • AUTOMATIC
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MRDAN89
  • MEMBER
  • 2 POSTS
My heater is working erratically. It will defrost the windshield. but the cabin temperature does not reach the temperature that I set it at. The blower is fine but all I get is cool air blowing.
Feb 15, 2009 at 8:32 AM
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GFIMOTORCARS
  • CERTIFIED EXPERT
  • 673 POSTS
Sounds like you may have a faulty heater exchange valve. When these fail coolant is restricted into the heater case producting merely cool air out of you a/c vents. The heater exchange valve is located on the firewall. Follow the heater hoses to the metal exchange block on the firewall.
Feb 15, 2009 at 5:43 PM