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  #1  
Old 08-07-2006, 07:07 PM
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Join Date: May 2005
Location: Fernandina Beach, Florida
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123 Drier has no visible flow - is this right?

I put a new compressor, drier, expansion valve in my 83 240D beater. The a/c keeps me cool, but only just, and works pretty hard at it. When it's 90 outside, it blows at about 60.

Anyway, I happened to look at the receiver drier, at that little porthole where you can see what's going on inside, and I couldn't see anything moving in there. Obviously something must be going through there because my a/c is working, but I thought maybe this is part of the reason it is not performing well (I have R12 by the way, with mineral oil)

Should I see the coolant flowing through the porthole?

I read that if you see bubbles you have a problem. What if you see nothing? Is that like a really big bubble?

There are 4 connections on the receiver drier :

the sensor (electronic)
in
out
and another bolt. What's this bolt for ? It looks like it could block the flow of refrigerant. Sheesh.

Help!

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  #2  
Old 08-07-2006, 07:28 PM
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Location: Austin, TX
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Quote:
Originally Posted by pdrayton View Post



There are 4 connections on the receiver drier :

the sensor (electronic)
in
out
and another bolt. What's this bolt for ? It looks like it could block the flow of refrigerant
You're missing something. You shoud have 2 sets of electrical connections, in addition to the in and out ports.

You should have a temperature switch with spade terminals on a pigtail.

You should have a pressure switch with spade terminals directly on the switch body. This pressure switch fits into a hole covered with a hex head plug directly at the inlet.

With no pressure switch, your compressor clutch should never engage, unless someone has jumped the wiring...

Rgds,
Bob
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  #3  
Old 08-07-2006, 09:07 PM
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Location: Fernandina Beach, Florida
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So.....I'm a liar.....

Bob - you got me - it does have 2 electrical connections, each with 2 spade terminals. I went to take a picture, only to find the batteries are flat in the digital camera. So I'll have to use 1000 words......

One switch thing is on the refrigerant hose nearest the condenser, the other switch is near it but mounted on the drier body. And there is the out hose, and then a bolt...

I undid the bolt a little and coolant started flying out so I closed it sharpish!

Still, no visible flow in the porthole.
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  #4  
Old 08-07-2006, 09:40 PM
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Location: West of Ft. Worth. TX
Posts: 4,164
That little sight glass is there to tell you that a set of guages needs to be attached in order to find out what is going on. It's basically a "warning light" for the a/c system.
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84 300SD 350K+ miles ( Blue Belle )
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  #5  
Old 08-07-2006, 09:57 PM
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Quote:
Originally Posted by pdrayton View Post

I undid the bolt a little and coolant started flying out so I closed it sharpish!
Some driers have a port to accomodate a different model temp switch. The unused port should remain plugged.
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  #6  
Old 08-07-2006, 11:47 PM
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You can use the sight glass as a rough estimate of system charge. The bubbles should clear up completely when the system has the right amount of charge. Mine did right before I emptied my fourth can into my empty system. And yes, I was using gauges to verify pressures and they corresponded.

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1984 300D 225K
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