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-   -   Sudden loss of AC performance, Monovalve? (http://www.peachparts.com/shopforum/showthread.php?t=405494)

Roncallo 06-05-2020 08:13 AM

Quote:

Originally Posted by vwnate1 (Post 4055501)
You jogged my memory : Thursday I took my Foster boys all over Los Angeles in my Rich upgraded '82 240D ~ in Woodland Hills it was 103* F and the dash vent read 60* F on the freeway at 60 MPH .

In North Hollywood I encountered 106* F and the dash vent was 58* F .

In Pasadena it was 104*F and the dash vent was 56* F for a short time then crept up to 60 ~ 62* F so I guess I'm good to go, a 40* F TEMPERATURE DROP is good enough for me .

Did you have the windows open when you took those measurements. The chart I posted is for performance results with windows open.

vwnate1 06-07-2020 04:04 PM

Actual Temperature
 
No Sir ! .

it was too dang hot .

For me, a thirty or forty degree drop is acceptable...

Roncallo 06-08-2020 12:04 AM

Quote:

Originally Posted by vwnate1 (Post 4056584)
No Sir ! .

it was too dang hot .

For me, a thirty or forty degree drop is acceptable...

I got 30, I'm going to have to live with that, But I got 34 when I closed the windows.

Roncallo 06-13-2020 04:07 PM

4 Attachment(s)
I replaced the expansion valve because I wasn't happy with the low low side pressure

Got everything installed and up an running. Some good news some bad news. On first attempt the copper cone seal was not seated properly and leaked immediately. I was always afraid of this happening and this time it did. I hope I didn't cause a scratch in the sealing surfaces on either the TXV or Evaporator. So far I cant detect anything with my leak detector but I need to get ready top get on the road. I'm leaving for NY in the AM. I replaced the seal and successfully charged 32.5 oz. I didn't want to go any more than that at the moment because that's about 2 oz more than my calculation say is required, but sub cool is still only at 4°. When I get back I may try a bit more.

Ambient temp today was 82°.

High side pressure was 215PSI

Low side pressure was still low at 14PSI

But Duct temp was down to a cool 44°F



I have no idea why the low side will not come up but the high side looks a little better. And I have no idea why its suddenly down to 44° duct temp. I will have a little more testing to do when I get back. I wish I could take the car to NY but there is still a lot of putting back together to do.

vwnate1 06-13-2020 10:45 PM

DUMB QUESTION :
 
Where does this conical copper washer go ? .

TIA,

Roncallo 06-13-2020 11:46 PM

Quote:

Originally Posted by vwnate1 (Post 4059278)
Where does this conical copper washer go ? .

TIA,

The conical copper washer is optional and goes between the expansion valve and the evaporator. There is also one for the liquid line to the expansion valve. Mercedes Benz publishes two torques for the expansion valve. You get to apply less torque if you use the washer. Since the expansion valve is in an impossible place to get at and tighten, I elected to use the washers.

Roncallo 06-27-2020 08:54 PM

3 Attachment(s)
First thing to learn in AC school is to check your equipment. I have been chasing a ghost for the last month and this is what I found. The thermometer that reads 42° is about 35 years old. The other two I just got in to replace it. Good news, that means my AC is working really really good.

vwnate1 06-27-2020 10:39 PM

Thermometers
 
Thanx ! .

When I took my Delco factory training there were no digital thermometers that I knew of .

My fingers or face tells me I'm not getting anywhere near 32* F out the dash vents.....

I have a digital laser thermometer, I wonder where I left it ? .

We're going to the Mojave Desert to - morrow, the weather report says there may be clouds ~ I certainly hope so .

Roncallo 06-28-2020 11:14 AM

Big success on the AC. These taken 81° F ambient 65% RH, using standard test conditions, engine at 2000RPM windows down, blower high, recirc off. Also checked evaporator temp operation. Engine at idle, blower low, windows closed recirc on. Clutch cycled off at 32°F back on at 36° F.

What a difference with new thermometers. 40° Duct temp.

AC is done.

See Finishing Samson for pic.

http://www.peachparts.com/shopforum/4065005-post100.html

unavita 07-05-2021 03:48 PM

Quote:

Originally Posted by Diseasel300 (Post 4049967)
The stock 560SL is the one I was suggesting to try the 12V on. If you see a difference, the silver box is probably the source of the leak, not the monovalve cartridge.


Thank you for this.



I read all the comments on p1 and p2, did the test with 12v's and my AC was no longer blowing hot air... but not cold air.



Do you have the name and pn for the "silver box"? Or are you just replacing the capacitors in it- renewing it?

vwnate1 07-05-2021 05:38 PM

COLD AC
 
Good to hear you're satisfied with it, did you take note of the pressures ? .

My SANDEN and PF condenser are working but not as cold as I'd like, I'm pretty sure it's time to dig out my old gauge set and test and adjust, know what pressures work for some one else would be handy as a starting point...

I'm running R134a now .

TIA,

-Nate
Quote:

Originally Posted by Roncallo (Post 4065010)
Big success on the AC. These taken 81° F ambient 65% RH, using standard test conditions, engine at 2000RPM windows down, blower high, recirc off. Also checked evaporator temp operation. Engine at idle, blower low, windows closed recirc on. Clutch cycled off at 32°F back on at 36° F.

What a difference with new thermometers. 40° Duct temp.

AC is done.

See Finishing Samson for pic.

http://www.peachparts.com/shopforum/4065005-post100.html


URO Parts Support 07-13-2021 07:10 PM

1 Attachment(s)
Hi guys, we just completed the first production run of our redesigned Heater Valve Repair Kit 000 835 0644R, which has a softer rubber diaphragm for easier movement and some minor improvements to the smaller pieces.

These are now available in our warehouse, and should show "in-stock" on retailer websites. If you need one, don't wait too long, our next run won't be for a few more months.

http://www.peachparts.com/shopforum/...008350644r.jpg

vwnate1 07-13-2021 08:05 PM

Monovalve Kits
 
Oh boy ! .

I'm off to order two....

EDIT : OOPS ! Pelican parts doesn't have them :confused::( .

URO Parts Support 07-14-2021 02:58 PM

^ Thanks, just sent Pelican an email asking them to add them.

vwnate1 07-14-2021 07:08 PM

Uro Monovalve Kit
 
O.k., thanx ! :) .

Will this part fit my brother's 1997 300SDL ? it has the OM603 inline 6 engine .

TIA,


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