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  #16  
Old 06-28-2008, 09:25 AM
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Quote:
Originally Posted by brandlj View Post
My electric cooling fan will cycle from low speed to high speed when I am in the drive thru at McD's when it is really hot out.
What's the temperature reading on the dash gauge when this event occurs?
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  #17  
Old 06-28-2008, 12:48 PM
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Location: central washington
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ac help

I brought my 87 300d in for ac work ,mechanic converted it to 134a, fixed a couple o-rings,filled it up ,ran system ,and told me the compressor ran constantly, which he said was incorrect.Then turned off car and then all 134 a blew out relief valve on back of compressor. system was only blowing at 70 degrees he said. He said I need a new compressor.Sound right anyone? thanks in advance-Joh
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  #18  
Old 06-28-2008, 01:39 PM
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It sounds like you may have a restriction in the system. Was the dryer replaced?
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  #19  
Old 06-28-2008, 02:04 PM
1986 300sdl 1985 380se
 
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Location: West Monroe LA
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Quote:
Originally Posted by Brian Carlton View Post
What's the temperature reading on the dash gauge when this event occurs?
Usually about 90 degrees. It never goes any higher than that. It always sits at 80 or a little below.
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1986 300sdl
1985 380se
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  #20  
Old 06-28-2008, 03:22 PM
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I only had the o-rings replaced,no dryer,whats a dryer?does this sound like a bad compressor, to me it seems like it pumps up too much pressure and doesn"t bleed off or cycle and stop pumping .
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  #21  
Old 06-28-2008, 03:54 PM
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Originally Posted by brandlj View Post
Usually about 90 degrees. It never goes any higher than that. It always sits at 80 or a little below.
Then, something is amiss. The fan should never run at high speed until the coolant reaches 105C.

Most of us have never heard the fan at high speed.............I certainly have not.
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  #22  
Old 06-28-2008, 03:59 PM
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The dryer is built into the receiver, and sits in the liquid line between the condenser and expansion valve. It was probably replace if o-rings were changed, because that opens the system to air. Additionally, the desiccant used in the old R12 dryer is not compatible with R134a and its oils, so it should always be changed for a conversion.

Also, there is a low-pressure cutout switch on the dryer, which should be replaced with a binary (high-low) pressure switch. Any replacement switch will be a binary switch, since it never hurts to use one for R12.

If you have a restriction in the dryer, the inlet line will be hot and the outlet line will be quite cold. The same goes for the condenser (or any other liquid-bearing part).
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  #23  
Old 06-29-2008, 12:34 PM
1986 300sdl 1985 380se
 
Join Date: Aug 2005
Location: West Monroe LA
Posts: 484
Quote:
Originally Posted by Brian Carlton View Post
Then, something is amiss. The fan should never run at high speed until the coolant reaches 105C.

Most of us have never heard the fan at high speed.............I certainly have not.
You Are absolutely correct!!!! What I am hearing (actually sensing it coming on ) is the low speed aux fan. I went out to test this yesterday. The low speed fan will come on and I can see my needles jump a little when it does. I guess it is just a little more draw on the electrical system.

I tested my high speed fan and it does work, but it never has come on by itself.

Thanks for helping me clarify this.
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