QuestionQUESTION: My 1977 300D No heat AC squeals win I push the defrost or turn on compressor.I just put a new motor in it.My mechanic says its a black climate control box.It has about 10 air lines coming out of it.Somebody said they cost about 1200.00 bucks.Im not sure this is it.And can't afford to have him do it.Is this what it is.Whats the amplifier?Could that be it?This upsets me I spent all that money on the new motor.Live in Iowa gotta have heat.Mechanic knows allot about tractors not to much about mercedes.Is there a rebuilding kit for the climate control box?What's that cost?Can fix myself just gotta know where to start.
ANSWER: Robert,
Let's start from the first. How long have you owned this car and how many miles on it. Just put a motor in it? Another engine you mean? If so then the belt has stretched a little and need to be snugged up.
The squeal is from the AC belt when the AC compressor is engaged. The compressor engages automatically when you switch on the defrost. The heater air is blended with the dryer ac air to help dehumidify it and dry of the windshield.
First you need to determine if the hot water is getting to the heater core.
Maker sure the radiator is full as is the coolant tank.
If this model has a monovalve, then this may be your problem. The valve is located in the fire wall pocket. It has multiple water hoses and an electrically operated solenoid plunger.
When heat is called for, this plunger moves up or down to determine the location and amount of water released.
Good luck,
Rob
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QUESTION: Rob It was a brand new motor.Tighten belt I think it is the compressor.The heat issue. Water is geting to heater core.No monovalve.Back to the black climate contol box.Where would I find a used one?Or rebuild the one I got.Plus does the amplifier affect the heat?Where is that located.For one single black box it has 4 water outlets and 12 airlines.I have had this car about 4 years.Never had heat.Bought in the summer.Got ripped motor was shot.Not so bothered about A.C just heat.Thanks for the input Rob.
ANSWER: Rob, are you getting air flow from the duct work. Is the heater blower motor operational.
Seem to me that this should be a matter of making sure air is circulating over the heater core and back into the passenger compartment.
Check to see if the blower box flaps are directly controlled by cable from the dash control or are vacuum servosed usded to open and close the Hearer door.
If they use vacuum operating valves then your problem lies in the engine vacuum pump or associated tubing to the heater controls.
I would search on ebay or craigs list for a 1977 300D.
You could also join www.benzworld.org/.
It has been a good source for parts location and info too.
Good Luck let me know how it goes.
Rob
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QUESTION: Rob checked Benz World E-Bay What is the name of that black box with all the airlines.There are some vacuum lines by the fuse box.They go into a three way.But not hooked up.Where should that main line go to for vacuum?Are those for the heater?I can not find a monovalve nowhere.I went through 142 pages on Benzworld.My eyes are bugged out.Thanks for having the patients with me.Dumb I guess.
AnswerRobert,
HVAC control valve. You may try hooking up the vacuum hoses to see if it works They should be plug if they are actually vacuum hoses. Golf Tees are generally used for this purpose.
Here is a URL for a forum discussion that may be of help to you. Copy/past it to your browser and check it out.
http://www.peachparts.com/shopforum/showthread.php?t=252090
You may find a way to get the Heat you want.
The AC compressor is controlled through the servo unit.
Let me know it this helps.
Rob
