A/C Question - Page 2 - PeachParts Mercedes-Benz Forum

leathermang · #16 08-28-2009, 10:00 AM

Mark, LOLOL, Those service valves are NOT completely intuitional in their operation. I have to really think about them...and keep a diagram near by when I use them....
So that was a great add to what might be happening...because as Larry said the other two scenarios are not likely...
I only use mine once every three or four years... perhaps I should play with them more ?LOL

Mark DiSilvestro · #17 08-28-2009, 10:16 AM

Quote:

Originally Posted by leathermang

Mark, LOLOL, Those service valves are NOT completely intuitional in their operation. I have to really think about them...and keep a diagram near by when I use them....
So that was a great add to what might be happening...because as Larry said the other two scenarios are not likely...
I only use mine once every three or four years... perhaps I should play with them more ?LOL

I sometimes worry that someone might feel slighted by one of my suggestions, but without knowing the experience level of others on these Forums, I figure too much info is better than not enough, and so often some seemingly silly little detail gets overlooked.

Happy Motoring, Mark

leathermang · #18 08-28-2009, 10:33 AM

Mark,
Silly details one does not know about can literally blow up in one's face... I say post all the info we can and let people be on the safe ( and economical ) side...
If they are so insecure as to take offense at people trying to help them out ... (and remember you are not just addressing the OP.. but all those that read the post later..) then they do not understand the concept of ' forum' and should not be here.

That is why I get upset about some people posting about alternative refrigerants without mentioning potential problems . It would only take about three sentences to do that... so when they regularly refuse it looks like they are promoting those other methods as compared to giving all the info they can for their fellow forum members and then letting them make the best decision they can based on all the available facts...

#19 08-28-2009, 12:34 PM

Quote:

Originally Posted by Mark DiSilvestro

Or both service valves are open on the guages, causing hi-lo pressure to mix.

Happy Motoring, Mark

Yes, hadn't thought of that. For someone not accustomed to using them, maybe they think that they have to open the valves in order to take pressure readings.

barry123400 · #20 08-28-2009, 12:40 PM

I know nothing about air conditioning. Other than the fundemental principals. So I know less than you.

The loss of the cold pipe was after you hooked up your gauges. You had it before so the compressor is at least semi okay and running. It is at least reasonable in my mind that the cross flow or bypass from the low side to the high side through the gauges did occur.

If practical carefully clamp off the input and output hoses to the heater core. See if any cold air results in the cab. Usually clamping off one would normally disrupt any circulation. In my recent learnings this apparently is not positive on some of these cars.

My cautious nature would make me unplug the booster pump. If the pump were to run it may be in a stalled or heavy current mode. Heavy current is known to damage the control unit. So much so an aftermarket fuse in it's electrical feed has been recomended by some.

Keep the air conditioning specialists on site posted as you go along. Plus it never hurts for an old dog like me to learn a new trick or two. I will probably need everyones help in the future when I tackle some of my non working systems.

Doug183 · #21 08-28-2009, 02:32 PM

First, thanks for everybody's help... please the more info the better - especially the small details, those are what are usually critical.

1. Valves. I assume you are talking about what's on the gauges. As far as I can tell, there is only one valve on the gauges and I want to say it is on the high side (it could be on the low). The actual dial turns and says open and closed. The other dial very clearly states there is no valve on that side. When the first valve is open, freon leaks out from it. Closed I get the aprox 90 and 90 psi on the high and low side.

2. A month ago after putting new oil and freon in the AC system, I was getting cold temps on that pipe. Then I was running and fixing the car for awhile and didn't check it. I could have even run the car for a little time (less that 100 miles) with the AC engaged and not blowing cold air. THEN I bought some gauges, got my test results and THEN realized that the pipe was no longer getting cold. So it could very well be like there was a blockage in the system and that blew the compressor or the compressor just went or there is something I am completely unaware of.

I am gone for 10 days and will not be able to test for awhile but please feel free to add you suggestion.

Doug

PS. How can I tell if the middle of the compressor is turning? I apply 12v, hear a click and the engine kind of shudders like there is a drag on it. It could be the clutch is not fully engaging the compressor, but how can I tell? A dental mirror of the sorts?

Matt L · #22 08-28-2009, 03:29 PM

I've never seen a gauge set with only one valve. Most have two; my set has four.

Can you post an image of this gauge set, so we can get some idea of how it designed to be used?

The nose of the clutch spins with the compressor input shaft. You may need to shine a flashlight down on it, but it will be obvious if it is spinning or stopped.

leathermang · #23 08-28-2009, 04:27 PM

Quote:

Originally Posted by Matt L

Most have two; my set has four.
Can you post an image of this gauge set, so we can get some idea of how it designed to be used?

FOUR ? Well, aren't you the fancy pants !!!
LOL, How about posting a picture of yours also...and tell what all those valves control...

Matt L · #24 08-28-2009, 05:18 PM

It's a Mastercool device, pretty standard 4 ball valve setup.

The additional two valves make evacuation and recharging a snap. Hook the vacuum to the black valve and the refrigerant cylinder to the yellow valve. Close yellow, open black, red and blue to evacuate. Close black and open yellow to charge. No swapping of hoses, no introduction of air.

leathermang · #25 08-28-2009, 06:59 PM

Very Cool Matt, That does sound cool... so once you have ' purged' your lines and are all hooked up there is no more messing around.... Thanks.

Matt L · #26 08-28-2009, 07:15 PM

Here's a link to the one that I have:

https://www.ackits.com/pc/86972/RefrigerantGaugeSets/86972+-+Mastercool+Professional+%284-Way+Gauge+Set%29

The gauge set has 1/4" fittings on all ports, so it would work fine for R12/R22 or whatever, but the hoses it comes with all have 134a fittings at the opposite ends (1/2" ACME or 14MM connection to the service port connectors). So I wouldn't buy that set for R12 work, if you can get just the manifold and gauge part without the hoses. It should be quite a bit cheaper that way, and you don't need the 134a stuff.

Another option would be to connect a pair of valves to the yellow connection on a two-wheel manifold, and that would work just as well. Mastercool and others sell ball valves with 1/4FFL-1/4MFL connections (so they go on the end of a hose) for about $15 each. If you have one port on the yellow connection, you'll also need some sort of "Y" connector, which sell for about $8 or so.

leathermang · #27 08-28-2009, 09:54 PM

Well, now I can see why I do not have that rig...
$243 and it does not come with any R12...
LOL

Matt L · #28 08-28-2009, 11:48 PM

Yep, it's a bit pricey, and it's pretty nice. But as I said, you can have the same functionality with your current gauge set for another $40 in valves and a "Y" fitting. It does make things a lot easier.

leathermang · #29 08-28-2009, 11:54 PM

How about diagramming that for me Matt ?
Can't pm you... tried to...can you PM me ?