A/C Compressor recommendation - PeachParts Mercedes-Benz Forum

Doug183 · #1 10-10-2011, 09:59 AM

I have a 1983 300D Turbodiesel, that I bought 3 years ago. Last spring, I decided to repair the A/C on the car. There is a sticker in the engine compartment that at some point in the past, this car was converted to R134a.

• I replaced the climate control unit.
•* Then I took apart the A/C system and flushed it out according to instructions I found on PeachParts.
• From ********** I bought a new Behr R4 compressor, and new drier, new temperature sensor, new high low pressure switch, expansion valve (R12/R134a compliant), new o-rings. New oil compatible with R134a.

The system worked great for at least 1 summer and this second summer my wife drove the car, so I am a little unclear if the A/C worked this summer as well. However currently, the issue is the system is not working again.

I checked the pressure with a Manifold gauge set and it looks like the pressure on the low side is normal, but the High side reads nearly 0. I can hear the clutch engage on the A/C compressor. This all leads me to believe that my A/C compressor has failed after only 18 months (of course out of warranty.)

So my questions are:
•*Am I missing something? Could my compressor still be OK?
•*If I am going to replace this compressor again, is there someplace more reliable to purchase one. The one on ********** (Behr) looked great when I got it and was very affordable, $236, but if they are unreliable, whats the point.

Thanks
Doug

leathermang · #2 10-10-2011, 11:33 AM

You need to pressurize the system with nitrogen and four oz of R22 and use a sniffer to check for leaks...

EPA rules allow you to use this and vent to check for leaks.

if the leak is at the front of the compressor that may be all that needs to be fixed..

but you do not have enough info yet to make any long range plans or conclusions.....

Avoid running your AC because all your lube for that compressor comes from being mixed with the refrigerant...which looks to be basically gone.. when you take readings always post them if you refer to them in the post... ' low' and other things are subjective ...

read the reference thread in my sig listed last.... report back your leak results...

vstech · #3 10-10-2011, 12:52 PM

what is the "normal" pressure you have on the low side? a 0 reading on high, with the compressor running, and a "normal" pressure of 40 or so on the low side, indicates to me that your gauges are not working... it's impossible for the high side to reach 0 with pressure of any amount on the low side.

and HERE on peachparts is the best place to source any automotive parts! Give Phil a call, and he'll source the best compressor (compressorworks) and the best price!

Quote:

Originally Posted by Doug183

I have a 1983 300D Turbodiesel, that I bought 3 years ago. Last spring, I decided to repair the A/C on the car. There is a sticker in the engine compartment that at some point in the past, this car was converted to R134a.

• I replaced the climate control unit.
•* Then I took apart the A/C system and flushed it out according to instructions I found on PeachParts.
• From ********** I bought a new Behr R4 compressor, and new drier, new temperature sensor, new high low pressure switch, expansion valve (R12/R134a compliant), new o-rings. New oil compatible with R134a.

The system worked great for at least 1 summer and this second summer my wife drove the car, so I am a little unclear if the A/C worked this summer as well. However currently, the issue is the system is not working again.

I checked the pressure with a Manifold gauge set and it looks like the pressure on the low side is normal, but the High side reads nearly 0. I can hear the clutch engage on the A/C compressor. This all leads me to believe that my A/C compressor has failed after only 18 months (of course out of warranty.)

So my questions are:
•*Am I missing something? Could my compressor still be OK?
•*If I am going to replace this compressor again, is there someplace more reliable to purchase one. The one on ********** (Behr) looked great when I got it and was very affordable, $236, but if they are unreliable, whats the point.

Thanks
Doug

Doug183 · #4 10-11-2011, 08:29 AM

When I have a second, I will go out and an re-check the numbers. I also will probably take the car to a real A/C place and have them pressure check and look for leaks. I am very suspicious of the seals between the plate with the two hoses (hi/lo) and the compressor and my work with them. I was never clear which seal went where - red and black, thick and thinner. I mean it seemed there was only one way to make plate with the hoses on it seat evenly, but...

tex599 · #5 10-11-2011, 09:36 AM

x2 on not running the A/C, this is what destroyed my compressor several weeks ago. Mine leaked from one of the seals on the compressor. I ended up replacing all the o-rings, flushing and refilling with r-12.

tangofox007 · #6 10-11-2011, 09:43 AM

Quote:

Originally Posted by Doug183

I am very suspicious of the seals between the plate with the two hoses (hi/lo) and the compressor and my work with them. I was never clear which seal went where - red and black, thick and thinner. I mean it seemed there was only one way to make plate with the hoses on it seat evenly, but...

Some compressors do not come with the proper seals. And even with the "proper" seals, getting a good seal is almost impossible with the new style seals. The old o-ring arrangement was a much better option, given teh hose manifold design.

Yak · #7 10-11-2011, 10:48 PM

Quote:

Originally Posted by Doug183

When I have a second, I will go out and an re-check the numbers. I also will probably take the car to a real A/C place and have them pressure check and look for leaks. I am very suspicious of the seals between the plate with the two hoses (hi/lo) and the compressor and my work with them. I was never clear which seal went where - red and black, thick and thinner. I mean it seemed there was only one way to make plate with the hoses on it seat evenly, but...

Different compressors use different seals. I took off a Harrison that used two black of equal thickness. I replaced it with a CompressorWorks that used a yellow and green (I think, maybe yellow and red, it's been a while). There was also a diameter difference with the yellow being larger.

The trick is to get it even and have the sealing washers stick up just a tad above the compressor. That way the manifold is sealing against the rubber on the sealing washer and not against the metal on the compressor.

1980sd · #8 10-12-2011, 12:10 PM

Man, that stinks

It sounds like your gauge readings aren't right. Could be that the connector to the hi side is wonky or something?

leathermang · #9 10-12-2011, 04:54 PM

Renew the schroeder valves at the first opportunity in this process....
Easy when empty.....

Doug183 · #10 10-24-2011, 02:07 PM

Finally had an opportunity to re-measure my psi.

System off: Low 25psi, High 40psi
System running: Lop 0 psi, High 60 psi.

I am guessing that means I am low on refrigerant and that the compressor is working. Also, I am guessing, that since I re-built the system last year with all new parts and filled the system, that I have a leak somewhere and that will need to be addressed.

Please confirm, clear-up and/or advise.

Thanks
Doug

leathermang · #11 10-24-2011, 03:02 PM

Quote:

Originally Posted by Doug183

....Please confirm, clear-up and/or advise.....Thanks,Doug

Did you see post number two ?

Doug183 · #12 10-24-2011, 04:37 PM

Do you mean with the R22 and nitrogen? Sounds great but I have no idea where to get those items.

leathermang · #13 10-24-2011, 04:41 PM

Are you wanting to do this yourself ?
What kind of AC tools do you have ..... or want to get ?
If not, read up on the procedure so you can instruct someone or a shop as to what you want done....
Have you read the sticky referenced at the bottom of my signature ?

Doug183 · #14 10-24-2011, 04:45 PM

No, I think at this point its best to get a professional involved as clearly, I didn't complete this repair correctly the first time. Also, I need to discharge and recharge, and new R134 has gotten so expensive in California, its just better to let a pro do it.

Is there a specific thread on this? I know the 'vacuum test' is not a valid test to see if the system will hold pressure, but other than that, not sure what else to say except "Can you pressure test this system with Nitrogen and R22"

leathermang · #15 10-24-2011, 04:49 PM

You missed my ref to my signature because I edited it while you were posting... that thread is lot of reading....but I am pretty sure it is in there... if you read it and still have questions we will make sure you are comfortable with what you need to do...
Many, if not most of us, do the AC stuff because we can not trust or afford to have a ' pro' ( who may know less than we do about the MB system) do it....
Ac work is real aggravating and tedious.... only at the end where you are nice and cool and trust the system should last a long time due to you following the rules is there any feeling of satisfaction...