1995 Mercedes E300D air conditioning system clean!

[Djsantanvalleyaz]

I recently purchased this low mile (498,000) e300d. After replacing the entire vacuum line system, all a/c vents worked! But the temperature was not as cold as could be.

I hired a local self proclaimed tech and he pumped out the system.

Then after installing 2 cans of freon, should almost take 3, the system pressure reached 400lbs.

The tech now proclaims there is a blockage from a previous compressor failure and he wants to clean the system. Using acetone.

Upon investigating on line, it appears all hoses should be removed and a new drier/accumulator should be installed.

I will not be returning to visit the wanna be tech.

Any suggestions on who in Arizona has their act together on ac systems?
Does Peach sell the drier?

DJ at 112 degrees

[shertex]

Yes, you can buy drier from Pelican.

Congrats in advance on your upcoming 500k milestone!

[Maxbumpo]

In my humble opinion, the cleaning is a great idea. I agree with you that the receiver / dryer (drier?) needs to be replaced, that is routine anytime the system is opened up. I'll bet that a new expansion valve is also in order, and the compressor is suspect if it has been pumping trash from a previous compressor failure.

What I fail to understand is why you are looking for a new tech. Would you have preferred that he simply replace components before charging it to test it? How was he (or anyone) to know there was a blockage? It seems that if the system was performing before you brought it in, he made an assumption that the compressor and maybe the expansion valve were good, and a simple/cheap first step is to evacuate the system, then check for leaks, then charge the system and test performance.

[Zulfiqar]

yes the unit needs to be broken down to the smallest bits - purge cleaning the evaporator is a chore on the W124 as its hidden behind the dashboard, but a smart technician can clean it out by removing the expansion valve that is next to the brake booster.

the high pressure can also be extra oil in the system.

Your tech sounds he did correct - one cannot assume a part is good or bad unless the system is run under full load in correct circumstances (full clean charge).

btw - dont overlook the cabin filters too, they are under the wiper cowling on this car and are 90% of the time overlooked because it was only the last 2 years of the W124 that had those.

[ROLLGUY]

Is the condenser/aux fan operating properly? Not having airflow across the condenser could surely cause a 400 lb reading on the high side. Your car has a pressure operated fan switch (unlike a W123=thermal fan switch), so the fan should come on almost immediately after the compressor clutch is energized. Don't overlook dirt and leaves in the condenser (behind the shroud), they will cause a lack of airflow as well. Another potential cause could be a stuck expansion valve. They are cheap enough that you can replace it just for piece of mind. If everything above is in order, I would be looking for a blockage somewhere (as others have said). It is so easy for the novice to just add refrigerant, and not start at the beginning. If the refrigerant is low or completely gone, there is obviously a leak somewhere. The first thing to do after recovering the remaining refrigerant, is to leak check with a dry gas. Any leak(s) need to be fixed before proceeding. It is also a good idea (as mentioned) to flush the system (evaporator, condenser, hoses), and then replace the receiver/drier, and add the proper amount of oil. Just adding refrigerant and an arbitrary amount of oil to a system is not good. Too much or to little is not good. Again, the best way is to start from scratch (leak check, flush, drier etc). That way you know that everything is the way it is supposed to be from the start.....Rich

[97 SL320]

What was the low side pressure during all of this 400 high? If the low side was zero, the "blockage" is a failed ( stuck shut / partially stuck shut expansion valve. )

If the low side was above zero ( depends on suction side temperature ) the aux condenser fans are probably not turning on.

[connerm]

When I removed the condenser from my 95 a couple of years ago, there was a LOT of debris under the fans and inside the fan although the area around the fan looked clear.