SDL + A/C = no go - Page 3 - PeachParts Mercedes-Benz Forum

Hit Man X · #31 07-02-2006, 12:16 AM

Well insert foul word here, I'll have to try the 420s then see. If not, I guess it'll be that speed sensor.

Brian Carlton · #32 07-02-2006, 12:18 AM

Quote:

Originally Posted by Hit Man X

Well insert foul word here, I'll have to try the 420s then see. If not, I guess it'll be that speed sensor.

Did you check for continuity to ground on socket #10? That's the definitive test for determining whether the CCU is telling the Klima to close.

JimmyL · #33 07-02-2006, 12:20 AM

See, if you had 123's you could just be worrying about the mundane loss of freon, or somesuch.......

None of the speedswitch stuff here.

Hit Man X · #34 07-02-2006, 12:20 AM

Quote:

Originally Posted by Brian Carlton

Did you check for continuity to ground on socket #10? That's the definitive test for determining whether the CCU is telling the Klima to close.

I don't have my multimeter here, I'll probably just end up buying one tomorrow.

Gotta love 95%+ humidity with low 90°F interior temps in the car when it was raining.

Brian Carlton · #35 07-02-2006, 12:24 AM

Quote:

Originally Posted by Hit Man X

I don't have my multimeter here, I'll probably just end up buying one tomorrow.

Gotta love 95%+ humidity with low 90°F interior temps in the car when it was raining.

Get the little pocket deal from Radio Shack. I've had mine for 15 years and it beats pulling out the high dollar meter for 99% of the tasks.

That's brutal weather........you drive with the right hand and wipe with the left????

Hit Man X · #36 07-02-2006, 12:27 AM

Quote:

Originally Posted by Brian Carlton

Get the little pocket deal from Radio Shack. I've had mine for 15 years and it beats pulling out the high dollar meter for 99% of the tasks.

That's brutal weather........you drive with the right hand and wipe with the left????

Hrm, have a link by chance? I was just there today picking up a small 25w iron to see what's up with that PBU.

Had the vent on and sweating like no other. I went out as I needed fuel and scored a tank of B100... $50 for about 20gal.

JimmyL · #37 07-02-2006, 12:31 AM

Quote:

Originally Posted by Brian Carlton

Get the little pocket deal from Radio Shack. I've had mine for 15 years and it beats pulling out the high dollar meter for 99% of the tasks.

I'm on my second one as the wire for the leads wore through from opening and closing so often. For work I almost always use the Radio Shack mini, and save the Fluke for when I'm in real trouble......

I hope you got more rain on your side of town than we did!

Brian Carlton · #38 07-02-2006, 12:35 AM

Quote:

Originally Posted by Hit Man X

Hrm, have a link by chance?

........naturally......

http://www.radioshack.com/product/index.jsp?productId=2103534&cp=2032058.2032235.2032305&fbx=0&allCount=8&fbn=Type%2FAnalog&f=PAD%2FProduct+Type%2FAnalog&fbc=1&fr=StorePrice%2FRSK%2F00001000%2F00004999&parentPage=family

JimmyL · #39 07-02-2006, 12:39 AM

I recommend this one:

http://www.radioshack.com/product/index.jsp?productId=2104114&cp=2032058.2032235.2032305&parentPage=family

I just prefer digital readouts.....

Brian sure beat me finding the link. That guy's pretty good.....

Hit Man X · #40 07-02-2006, 12:40 AM

So I just check to see it's not open?

RS is the place, I bet I could build a bomb with the stuff they have there if I was crafty in that manner. It's been raining since about noon, I had to sober up quick and fix the RR window of the SDL as the lil nylon slide decided to die last night. I think I fixed it in about 20min, just before the rain started!

Brian Carlton · #41 07-02-2006, 09:24 AM

Quote:

Originally Posted by Hit Man X

So I just check to see it's not open?

Yep, #10 socket has to have continuity to ground when the CCU is calling for the compressor to engage. Naturally, you'll need one of the three pushbuttons on the left side pushed in for the test.................

If you have continuity, the CCU is not the issue.

Hit Man X · #42 07-10-2006, 07:14 AM

Just an update for anyone that cares or for the future...

CCU seems to be the issue, trying to score a decent deal on a used one.

Hit Man X · #43 07-10-2006, 02:10 PM

Who knows, A/C comp came on and stayed on...

Anyway, I seem to have a high side block. Pressures are about 28psi low/240psi high at idle, motor hot, ~90°F outside. Around 62°F at vent... AT LEAST I can drop the humidity and be somewhat coool

Next, can I guess that the expansion valve is potentially the problem? If so, any reason to flush the system while it's out considering I'll need a new dryer (along with switches) too?

Hopefully my compressor isn't going.

tstarr · #44 07-10-2006, 02:27 PM

I'm not an A/C expert, but I just had something really fun happen this weekend which was A/C related and it might relate to your issue as well. I have been having A/C problems with my 87 300SDL for the last couple of years and had it in to be checked. I had one shop tell me it had a massive leak, and another tell me there was a big blockage in the system. A couple of months ago, I noticed that I was getting hot air leaking out of the vents even when the CCU was turned off. I replaced the thermovalve insert as the cheap fix for that, even though it didn't fit the symptoms I was familiar with. In the process, I broke the plug on the thermovalve and had to push it on as best I could. I decided to pull the plug piece off of my 300SD to replace. I pulled the entire thermovalve out of the SD, remembering that it was new about 3 years ago and the 87 one was original.

Once I put that in, I not only go no more heat leakage in the vents, but the A/C started working again! I ran it all weekend and this morning and it is still working. It was like a magic elixir for the car. I'm not really sure why, but you may want to at least check that out as well, especially if you have a parts car available. It's a real easy thing to do.

rrgrassi · #45 07-10-2006, 02:42 PM

Hit Man,

Any time you open up the A/C system, you will have to pump it down. Youare always better served to replace the dryer when you replace the expansion valve...The high side pressure seems a bit high, and you can damage the compressor from too much back pressure.

Those R4 compressors are junk new or rebuilt. I am suprised the MB chose to use them. R4's are known to grind themselves out, clogging the the dryer and expansion valve. GM had the same problems. I worked at Larry Lange Cadillac during high school, and during the summer, replaced about 4 compressors a week.

Good luck!