More ac problems - PeachParts Mercedes-Benz Forum

al b · #1 07-10-2010, 06:37 AM

I have a 85 300SD. I think there might be an obstruction in the line somewhere.The belt on the compressor is sliping. Is there a inline filter that might be cloged or somewhere that is pron for clogs.

vstech · #2 07-10-2010, 07:22 AM

nope.
assuming your belt is not worn, and the compressor is adjusted correctly, your compressor may be intermittently locking up.
what is the deflection on your belt? (how far can you push it with the motor off with your finger?)

#3 07-10-2010, 08:03 AM

With engine off, can you turn the front portion of the compressor clutch with your hand? If so, does it feel smooth with compression pulses or does it feel like it's full of rocks?

al b · #4 07-10-2010, 08:30 AM

New compressor. New belt. Ran for 20 minutes than started to squeel. Thought maybe there is somthing clogged in the line that is not the freon threww the line

#5 07-10-2010, 08:36 AM

I'm sorry if I have missed some other history from other threads. I hate for you to have to repeat it just for my benefit.

If the compressor was replaced after the internal failure of the previous compressor, complete and thorough flushing is required to remove any debris that might spoil the new compressor. Even with a clean system I've seen rebuilt compresssors fail very quickly.

Try turning the front of the compressor as I suggest and see if it turns smoothly.

Hope this helps,

vstech · #6 07-10-2010, 08:40 AM

yeah, can you itemize all that was done to the system prior to replacement of the compressor?
if all was done properly, the new belt may be riding on worn crank grooves, and it's settled into place, and all you need to do is readjust it. it's also possible the belt is too thin or not a metric belt, and it's a tad too weak to hold tension.

I found these...
New air compressor or rebuilt
expansion valve 85 300sd
ac vacuum question
whiew!
busy boy.
when it's the same scenario on the same car, and you need more help, it's usually best to continue the original thread.
helps us know what is going on.

leathermang · #7 07-10-2010, 08:48 AM

Belts can also have the wrong angle ..which results in not enough friction surface to transmit the load of the compressor through the belt to the drive pulley.

While few do it... the MB FSM says that after a compressor blow up.. that the manifold which attaches to the compressor ' must be renewed' ... replaced instead of trying to clean it... which I assume means that it has some kind of filter inside it which can not be cleaned.... which might fit this symptom as t place of too much internal obstruction..

vstech · #8 07-10-2010, 08:53 AM

hmmm. you've said this in a few other threads. I think I will cut the bad set I have apart and see if there is anything in there like a screen or such. I'm pretty sure it's just that the rubber in the lines is subject to full heat from the discharge of the compressor, and the heat weakens the rubber to the point that debris and such compromises the part. so, replacement is best for MB.

leathermang · #9 07-10-2010, 09:40 AM

Quote:

Originally Posted by vstech

.....hmmm. you've said this in a few other threads. ... replacement is best for MB.

LOL... so how many times do I need to repeat something for you to take notice/believe it ? If I know that number I can just say it repeatedly in the same post and get you sent off in the correct direction earlier ...

funola · #10 07-10-2010, 10:58 AM

Quote:

Originally Posted by vstech

hmmm. you've said this in a few other threads. I think I will cut the bad set I have apart and see if there is anything in there like a screen or such. I'm pretty sure it's just that the rubber in the lines is subject to full heat from the discharge of the compressor, and the heat weakens the rubber to the point that debris and such compromises the part. so, replacement is best for MB.

John, let us know what you find if you cut open the manifold lines. I always like to know why something is so, rather than following directions without question.

leathermang · #11 07-10-2010, 12:12 PM

Quote:

Originally Posted by funola

John, let us know what you find if you cut open the manifold lines. I always like to know why something is so, rather than following directions without question.

I totally agree.... but the only manifolds which are not on my 240 around here are on the parts cars which RLeo owns... EEEEEKKKKKKK!!!!!!
and I think he would notice if they were suddenly cut into pieces... I could claim FireAnts did the deed... they do attack some strange things...

Yak · #12 07-10-2010, 04:18 PM

Quote:

Originally Posted by al b

New compressor. New belt. Ran for 20 minutes than started to squeel. Thought maybe there is somthing clogged in the line that is not the freon threww the line

Another new compressor, or about a year old? The other threads are from 2009.

When it's not squealing, does it cool okay? Is the belt the only problem?

Can you do a quick summary:

New compressor clutch, or re-used old?
Flushed the system before installing?
R12 or 134a?
Added oil to the compressor? What kind? How much?

I'd look at the basic stuff first: a new belt that slips probably means it's not adjusted correctly. Three bolts on the back of the compressor to clamp it into place, and I think one adjuster to get the tension right.

Double check your belt size, too; size of the "V" and length of the belt.

Regarding turning the compressor: if it's a new compressor, you may need to borrow/rent the compressor wrench to rotate it - AutoZone, etc. If it's old, it may move by hand. You're trying to turn the front "triangle, not the part with the belt.

badgator · #13 07-10-2010, 09:14 PM

Mine was squealing within a month after I redid my ac, used autozone belt, started slipping at max adjustment(belt is too narrow).

Got correct continental belt, could barely get on, until I bumped the starter, works great.

al b · #14 07-10-2010, 10:35 PM

I replaced the compressor last year with a new one and due to my own faught runied it. I went and got a used one at the junk yard and it worked fine until the end of the year. This spring I repaced it with new one. I replaced the compressor,the filter-drier and belt. It started sqealing 20 min after I replaced it. It does work good. I did find a mechanic in Mitchiville Iowa threw peachparts. I talked to him and he is going to take a look at it when he replaces the back springs.

#15 07-10-2010, 11:08 PM

al,

How did the compressor fail? If it failed internally, it spread debris throughout the system. That debris, unless removed with a THOROUGH flushing of the system will destroy a new compressor and it could easily do it in 20 minutes.

I'm sorry that you had this kind of trouble as it is very discouraging.

Best of luck with it.