Low "high" side, high "low" side, does that mean the compressor is bad? - Page 2 - PeachParts Mercedes-Benz Forum

leathermang · #16 04-27-2009, 11:39 PM

Quote:

Originally Posted by JimmyL

OK, still don't know what car, but on most W123's, you have it bass-ackwards......

Jimmy, I do not see how his description is not correct..... can you explain what you are referring to ?

JimmyL · #17 04-27-2009, 11:48 PM

Quote:

Originally Posted by leathermang

Jimmy, I do not see how his description is not correct..... can you explain what you are referring to ?

On all my W123's the low side was on top in the front and the high side is down under the alternator, near the drain tube area if on a turbo model.
However, sometimes Euro models have different AC line routing and even a different compressor.
And, if the car in question is the W115 240D then it would have your style compressor, the big honkin York...

Quote:

Originally Posted by pizzachef

The port that's right on top in the engine bay is the high pressure port...its on a line between the compressor and the condenser (if I'm wrong, please tell me). The low pressure port is under the car, on a line between the evaporator and the compressor (again, if I'm wrong, please tell me). So the blue hose goes under the car, the red hose goes to the port on top.

leathermang · #18 04-27-2009, 11:51 PM

But he was using the description of where they were in relation to the compressor and condensor.. etc... which was correct in terms of low and high sides...

JimmyL · #19 04-27-2009, 11:56 PM

Quote:

Originally Posted by leathermang

But he was using the description of where they were in relation to the compressor and condensor.. etc... which was correct in terms of low and high sides...

Remember, I don't "think" my way through AC systems nor have the years of knowledge on AC systems and how they work as you do.

I need the "color by numbers" approach.

Hence the reason for trying to find out the car type. I know the system on my W123's and where every thing is, but it is more by the "trained monkey" approach. I'm slowly learning though, and follow your info closely.....

leathermang · #20 04-28-2009, 12:01 AM

I forgot... sorry..
but to give him unnecessary doubts due to your doubts... might drive him over the edge... LOL

JimmyL · #21 04-28-2009, 12:02 AM

My biggest doubt concerns the car involved.
That's why it's always nice to actually know what car a person is referring to.......

Mark DiSilvestro · #22 04-28-2009, 12:04 AM

Both my '82 240D and '84 Euro 300TD have a manual factory heat/AC system, with a Delco R4 compressor mounted under he left front of the engine, Both cars have the low-side charging-port in the fat metal line near the front of the valve-cover, right above the upper radiator-hose/thermostat-housing.
The high side port is in a slightly smaller metal line behind the alternator.

Happy Motoring, Mark

JimmyL · #23 04-28-2009, 12:11 AM

Quote:

Originally Posted by leathermang

But he was using the description of where they were in relation to the compressor and condensor.. etc... which was correct in terms of low and high sides...

His description [which he said he was "pretty sure"] is consistent with the correct locations, as you stated. That is actually a very helpful diagram.
My confusion, or question, concerns the fact that his "physical locations" of the described high and low side ports are exactly opposite of the run-o-the-mill W123 with an R4 compressor.

leathermang · #24 04-28-2009, 12:13 AM

Quote:

Originally Posted by JimmyL

My biggest doubt concerns the car involved.
That's why it's always nice to actually know what car a person is referring to.......

It is nice... but not something to depend on... these cars are 20-25 years old with the potential of having parts swapped to them from other systems, custom systems installed, idiots working on them over the years....

It is safer to go by where the port is with regards to the compressor-condenser relationship and the evaporator-compressor relationships..

JimmyL · #25 04-28-2009, 12:15 AM

Quote:

Originally Posted by leathermang

It is safer to go by where the port is with regards to the compressor-condenser relationship and the evaporator-compressor relationships..

pizzachef · #26 04-28-2009, 07:43 AM

I'm sorry, I thought I said it was the wagon in my first post...its the '85 300TD.

Jimmy, now you've got me worried, hopefully I'll have a forehead smacking moment when i go look at the car again...maybe my problem was trying to think my way through the system and I should just be following your color by numbers approach

The physical locations are just as you described...one right in front of the valve cover, and one behind the alternator (and the one behind the alternator is much thinner...I don't know why that didn;t occur to me). I must have screwed up when tracing the lines around the engine bay. I still need to do some verifying, but that means I'm trying to charge into the high pressure port

Someone should take away my harbor freight gauges.

This evening will be very telling...

vstech · #27 04-28-2009, 08:52 AM

points to jimmy!

leathermang · #28 04-28-2009, 09:22 AM

LOL.
Coloring by the numbers only works if no person in the car's past has messed up anything... better to carefully know and follow the tubes from one component to the next...
but if any OP is not thinking straight...or describing it well... blind help over the internet is by definition limited...

nhdoc · #29 04-28-2009, 07:16 PM

Quote:

Originally Posted by pizzachef

I'm sorry, I thought I said it was the wagon in my first post...its the '85 300TD.

Jimmy, now you've got me worried, hopefully I'll have a forehead smacking moment when i go look at the car again...maybe my problem was trying to think my way through the system and I should just be following your color by numbers approach

The physical locations are just as you described...one right in front of the valve cover, and one behind the alternator (and the one behind the alternator is much thinner...I don't know why that didn;t occur to me). I must have screwed up when tracing the lines around the engine bay. I still need to do some verifying, but that means I'm trying to charge into the high pressure port

Someone should take away my harbor freight gauges.

This evening will be very telling...

Well, since I am also working on a TD's A/C at this time I can tell you 100% that the hose in front of the VC is the low pressure hose. I have to replace mine as it is leaking. You can consider yourself extremely lucky that the can didn't explode from trying to charge on the high side...good news is not only are you lucky but apparently your system is working properly...now just hook up the gauges correctly and you should be all set.

pizzachef · #30 04-28-2009, 11:22 PM

Quote:

Originally Posted by Matt L

You checked again that you don't have the hoses reversed, right?

I'm going to change my initial response to this post. I did try to reverse the fittings and they wouldn't screw on the opposite fitting....the first time. Today, after some additional effort, the high pressure hose did screw on the correct port...I don;'t know why I had trouble getting it on there the first (and second

) time. I also followed the lines from the compressor incorrectly.

Hopefully someone else looking for which port is which will find this thread and not make my mistake. Thanks for all the help...the air blows cold now.