Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 05-23-2005, 01:39 PM
Registered User
 
Join Date: May 2005
Location: Tennessee
Posts: 4
Trying to diagnose A/C system

First off, here's the car I bought: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4549279201 . The two important parts regarding the a/c system are:

Items of note that have been replaced in the last few years include the radiator, the glow plugs, and the A/C compressor/associated system (new refrigerant compatible).

And:

The power antenna does not work properly nor does the A/C cool properly (needs recharging).

Now let me say, I know that sometimes (or oftentimes), the a/c needs more than a simple recharge, and I went into this knowing that it could need some repairs. Also let me say that I'm no car mechanic, but I am able to do basic tasks given the right tools.

I have no idea how to tell exactly what parts of the a/c system have indeed been replaced and what has not. I do believe the guy, he pointed out a lot of little things, I doubt he would lie about replacing parts of the a/c system. I do suspect the hoses weren't replaced, they appear to have the adapters put on them that you'd get with the R134a conversion kit (I can take pics if needed). I bought one can of refrigerant with leak sealer, and several plain cans. I followed the instructions to the "T". Start the car, engage the a/c, shake the can vigorously, connect the hose, hold can upside down and wait (yes, I did turn the screw to open the can and again to let it flow through). Now, I have since read that one should NOT hold the can upside down? That it should be held right-side up else it could cause damage? I swear though, the can says to hold it upside down, I even double-checked the instructions. So now, I'm confused.

Also, when I was putting in the first can, the pressure gauge spiked up to the yellow area (not red, but close). It went down into the green within a minute or less. The subsequent 3-4 cans I put in, it went barely into the blue ("filled") area, but down back to green ("low"). It is not putting out cold air, feels like outside air.

I've called around town, no one will work on a Mercedes. I'm hoping it's something simple I can diagnose and fix myself, or worst case something I can diagnose, buy the parts for, and take it somewhere and just say "this goes here".

I can take pictures if needed, can also take a video if you need to hear it running. I am not certain that the compressor is kicking in, but I have noticed at least more than once, that after I turn on the a/c the motor will sound like it's suddenly under a bit of a load, like any other car would after turning on the a/c. Sorry I can't be more descriptive than that.

BTW, I don't have any service manuals for it yet other than what it came with originally, but plan on going to Clarksville sometime this week or next and will try to remember to look for one (I live in a pretty small town, no Wal-Mart, AutoZone, Advanced Auto, etc.; NAPA is about 15 miles away).

Thanks!

Reply With Quote
  #2  
Old 05-23-2005, 02:51 PM
LarryBible
Guest
 
Posts: n/a
Holding the can upside down is the very least of your problems. If you have already put in the leak sealer, I'm afraid that you made a HUGE mistake. Once air hits the sealer, which is immenent, it will gunk up every component in the system. The only way it will ever be fixable would be to replace all components.

You should NEVER just start putting refrigerant into the system without monitoring BOTH low AND high side pressure, most especially a converted system. The high side pressure can easily get out of control.

I don't see anyway out of this mess without breaking federal law.

Best of luck,
Reply With Quote
  #3  
Old 05-23-2005, 04:31 PM
Registered User
 
Join Date: May 2005
Location: Tennessee
Posts: 4
Quote:
Originally Posted by LarryBible
Holding the can upside down is the very least of your problems. If you have already put in the leak sealer, I'm afraid that you made a HUGE mistake. Once air hits the sealer, which is immenent, it will gunk up every component in the system. The only way it will ever be fixable would be to replace all components.

You should NEVER just start putting refrigerant into the system without monitoring BOTH low AND high side pressure, most especially a converted system. The high side pressure can easily get out of control.

I don't see anyway out of this mess without breaking federal law.

Best of luck,
Ok, so I could get out of this mess if I break federal law...ok.... I'll run down to Mexico next week, what could I do down there to fix it?
Reply With Quote
  #4  
Old 05-23-2005, 04:53 PM
Ron in SC's Avatar
Registered User
 
Join Date: Aug 2003
Location: Charleston, SC
Posts: 1,095
You might want to consider replacing the compressor, expansion valve and receiver/dryer, in the grand scheme of things they are not that expensive. I think the compressor on that car is a Delco A6, not sure. Then flush out the hoses, evaporator, and condensor as best you can with those items installed on the car.

For real good advice by A/C professionals go to:

http://www.autoacforum.com/categories.cfm?catid=2
Reply With Quote
  #5  
Old 05-23-2005, 05:46 PM
LarryBible
Guest
 
Posts: n/a
Flushing the lines once the air activated sealant has been activated will do no good.

I am ASE certified in automotive air conditioning and have been working on automotive air conditioning since I was about 7 years old in 1956 with my Dad who was making his living with an independent shop installing and repairing automotive a/c systems. He was trained by Mark IV who was one of the pioneers in aftermarket auto a/c. So since I have only 49 years of automotive air conditioning experience, you probably should go find a professional.

To offer up another very good site for automotive a/c information, go to www.aircondition.com and then press "Straight to the Board."

Have a great day,
Reply With Quote
  #6  
Old 05-23-2005, 08:27 PM
Registered User
 
Join Date: May 2005
Location: Tennessee
Posts: 4
I've had some help troubleshooting the unit, here's what we've come up with so far:

The climate control seems to be working. Defrost works, and it will put out heat if you move the temperature wheel (as it should).

There is an audible click when a/c is engaged, and the engine sounds like it is under a load. You can turn a/c off and it'll disengage, turn it back on and you hear the click again and the engine is again under a load (so everything there seems to be working fine).

I got lost when the monovalve was mentioned, I need to do some research and find just what that is so I can clean it off and make sure it's not sticking. Also I hooked up the gauge to check pressure on the low side, it shows about 55psi when the a/c is turned OFF, and doesn't register anything when it is turned on.

A very, very stupid question...how much refridgerant should I be using? I stumbled on a page that said it would require 100g??!! If so, then I haven't even put half that in. Plus, I read somewhere else that R134a only needs to be charged to 75% of what you needed with R12.

Maybe I should just get some more R134a and see what happens. If I already screwed everything up, can't hurt right? I'd sure hate to waste $7 a can if that's not my problem. Might be something to try in between reading up on a/c systems.
Reply With Quote
  #7  
Old 05-24-2005, 08:40 AM
LarryBible
Guest
 
Posts: n/a
As I said before, you are going to have to monitor BOTH low AND high side pressure.

Maybe Ron In SC can offer some more advice from his professionals.

Good luck,

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Revamping A/C System and Controls dokhans Vintage Mercedes Forum 2 07-14-2004 01:22 PM
Can I always leave the A/C on? zeronero Tech Help 54 06-30-2004 09:40 AM
TIps to save A/C system 95E320cab Tech Help 9 05-05-2003 05:01 PM
300E A/C - please help diagnose 300EE320 Tech Help 10 08-29-2002 11:52 AM
A/C overhaul in 97 C230--Advice/Help needed rpmillie Tech Help 4 06-26-2002 12:42 PM



All times are GMT -4. The time now is 06:14 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page