Can the a/c condenser be flushed in place on '87 300SDL? - PeachParts Mercedes-Benz Forum

airfoill · #1 09-05-2016, 09:32 AM

I'm presently rebuilding the a/c system of my 300SDL. I've removed the compressor, expansion valve and the dryer. All three will be replaced with new. My next step is flushing everything. Assuming I've got access to both connection ends of the condenser, can I flush the condenser while in place or do I need to remove it then flush? My procedure is to use ac solvent pressurized into the condenser and then using compressed air to force the solvent out. Is that how you guys are doing it?

Thanks

Herb

leathermang · #2 09-05-2016, 10:17 AM

I think you can with a little plumbing....
I would split the ac solvent into two batches..not necessarily equal .. keeping the clean one for the last flush..
if you have some way to direct the flush coming out of the condenser into a container.. WITH some clean cloth on top.. like cheescloth... so you can monitor whether it looks like anything is still being brought out... you can reuse the flush multiple times... in the MB AC FSM they have a machine of course... and as it gets recycled it gets cleaned... but the point is that stuff made need to be in contact with the flush longer than one or two ' blow throughs' involves...
In that same vein... if you can fill the condensor by plugging the exhaust side... and leave it to do some of its work... that might be easier... then do the multi passes until clean fluid is coming out... then use the saved clean fluid... and you should be good..
Looking towards the next processes you are likely going to be doing... this might be a good time to buy or rent a small tank of nitrogen.... and use that to blow this through...and then to check for leaks when you put the system together...
AND it sometimes gets walked over in the discussions... but just putting nitrogen into the system a few times..( called triple evacuation if done three times obviously ). at pressure.... and then taking it out is one method to add to vacuuming for taking out moisture... HOME AC service people do this regularly since they have less access for things like flushing....

The other plumbing which might be needed is a connection to the input so you can pour the liquid flush into the condensor... so something like an upright fill tube might be needed.

You came to that Austin Get Together out at the park near the airport didn't you ?

airfoill · #3 09-06-2016, 10:41 AM

Quote:

Originally Posted by leathermang

You came to that Austin Get Together out at the park near the airport didn't you ?

If it was years ago, that was me!!

Demothen · #4 09-06-2016, 11:18 AM

I agree with LMG, but can offer a little extra advise.

I have used aerosol flush (from local parts store) with pretty good results. It saves you the trouble of figuring out a way to introduce it. It comes in a can with a hose to allow you to spray it easily. I'd figure two cans to do the condenser worst case, you might get by with one. You can also re-use it as LMG suggested, you'll just need a way to reintroduce it to the system. At least on my w123, there was a short hose going towards both the compressor and condenser that I was able to use to direct the flow.

I'd suggest trying to plug one end and fill it completely and let it sit for 15 minutes or so once or twice (or until the fluid stops getting dirtier), then flushing with clean flush and compressed nitrogen one last time to make sure it's really clean.

Just to be sure, you have an original serial style condenser right? Not a parallel flow? Not familiar with the 126, but on a 123 the original condenser is steel and has round tubes, while a parallel condenser is aluminum with square tubes.

funola · #5 09-06-2016, 11:20 AM

It can be done in place, but you have to make adapters with long hoses and use a pump and cycle the flush agent through it with a funnel filter (3 sheets of paper towel) to pretect the pump and keep debris out of the evaporator. Here's a video flushing my evaporator. https://www.youtube.com/watch?v=EcP8LJ90mAQ

I used a 64 oz OJ container mix of carb cleaner/ mineral spirit first, then purple power/ water mix as a degreaser, then gallons and gallons of plain water for a final rinse, alll via the solenoid pumpo. Then blow dry with compressed air. Getting all the water out is paramount. I blew it out many times over a period of a week, in the hot sun heated interior. To speed it up you can run some ethanol through it then blow it out with compressed air. I didn't have any but if I were to do it again I would buy some ethanol.

Demothen · #6 09-06-2016, 12:09 PM

I would certainly not say that you MUST make adapters and do it that way, Funola. That way certainly works, but using flush and letting it sit also works well.

leathermang · #7 09-06-2016, 12:20 PM

My visualization was based on the OP saying ac flush ..which I assumed to be liquid ... and I do not know where the input and exhaust connections are on his car... I assumed both to be low... thus I assumed plumbing to be needed to pour the liquid flush into the intake...if self propelled flush is used then that might be eliminated... just a way to connect would be needed...

Hit Man X · #8 09-06-2016, 08:13 PM

You would be a VERY wise person to pull it and have it pressure tested before putting any work into the existing condenser in the event it leaks. Ask me how I know this.

Plus the ability to clean as well as straighten the condenser fins is much easier with it on a bench.

Demothen · #9 09-06-2016, 08:42 PM

I guess the term aerosol flush is not really the right way to say it. The flush I got comes in an aerosol type pressurized can, but instead of having a spray nozzle it had a foot or two of clear hose with a rubber nozzle. The flush comes out as a liquid.
Are you going to run r12 or r134a?

funola · #10 09-06-2016, 09:57 PM

Quote:

Originally Posted by Hit Man X

You would be a VERY wise person to pull it and have it pressure tested before putting any work into the existing condenser in the event it leaks. Ask me how I know this.

Plus the ability to clean as well as straighten the condenser fins is much easier with it on a bench.

Very true! Goes without saying for any component in the AC system, especially the evaporator since it is so difficult to get to.

funola · #11 09-07-2016, 11:53 PM

Quote:

Originally Posted by Demothen

........

I'd suggest trying to plug one end and fill it completely and let it sit for 15 minutes or so once or twice (or until the fluid stops getting dirtier), then flushing with clean flush and compressed nitrogen one last time to make sure it's really clean.

Just to be sure, you have an original serial style condenser right? Not a parallel flow? Not familiar with the 126, but on a 123 the original condenser is steel and has round tubes, while a ...........

Plugging one end and filling it can't possibly work. It is difficult enough to get the air out with the end open due to the tubes winding up and down. That is why I chose to recycle the flush agent through it with a pump, which takes around a minute to purge all the air out till it's bubble free on the output clear hose.

My OE condenser is not steel. It is very light so must be aluminum. Check yours with a magnet. The only parts that is steel are the 4 small mounting brackets.

Demothen · #12 09-08-2016, 09:57 AM

Hmm. You make a good point. You'd need to fill it, then cap the end before it runs out. With the spray can I used I didn't have any problems getting it mostly full, I'm sure you'd want to do this a couple times.

I'm fairly sure my condenser was steel, as I thought it was rusted where it meets the hose, and it was a lot heavier than the PF one I have now. I might be mistaken. I'll check it sometime to be sure though.

leathermang · #13 09-08-2016, 10:13 AM

The name of the thread is about flushing the condensor in place...
while that can be done....
I certainly agree with Domethen and Funola in that a much much better job can be accomplished if it is taken out...
There are things which really need to be ' rotated' in order to get the flush into all the places for long enough... and for any particulate matter hoping to get out.. which gravity might preclude getting out unless you are able to rotate the condensor during flushing..

jay_bob · #14 09-08-2016, 11:44 AM

Great point LMG,
The tube at the bottom of the condenser probably angles upward after exiting the serpentine run.

If one tries to flush in situ the liquid and debris will be trapped at this point.

funola · #15 09-08-2016, 11:56 AM

It can be done in situ, but a pump is needed to cycle the flush agent continuously ,that's what the commercial flush machines do. This is my DIY setup, simple and effective https://www.youtube.com/watch?v=EcP8LJ90mAQ