My 1995 C280 is equipped with a refrigerant sight glass on the accumulator which shows cloudiness, indicating low refrigerant. Although it is still cooling it probably needs refrigerant added. Is it a good idea to recharge using the sight glass as an indicator so that it again is clear when compressor is operating or should you charge using a set of gauges? Also, it appears that charging port is on drivers side of engine below and to the left of the accumulator. Is this correct or is charging port located elsewhere.

You can get small cans or R14 at parts stores or Wal Mart that have gauges on them with all of the info you need to keep it under the danger range!


Brian Felts

Brian you living in Durham have accsess to some good MB indy mechanics and tool/part stores.

Never charge without monitoring high side and low side pressures. The walmart 134a hose/can does not have a hose for high side. you do not want to overcharge.

What makes you think it needs anything if cooling? When you connect to the schrader valves you run the risk of introducing air/moisture into system.

Sight glass is supposed to be clear when engine is reving and slight bubbles when you first turn it on then goes to clear/cloudy.

__________________
1993 Mercedes Benz 300D 2.5 205K (ex wife's)
1984 Mercedes Benz 300SD 320K (SOLD)
2004 Mercedes Benz C240 75K
1995 GMC Sierra 2WD 5.7L 188K
1983 Mercedes Benz 300SD 239K (SOLD)
1987 BMW 325i 220K (SOLD FOR SALVAGE)

609 Certification

The sight glass theory pertains to R-12; not R-134A.

R-134A sight glasses can run cloudy with sufficient charge.

As James said, you really need gauges to check the charge on an R-134A system. I would not feed refrigerant into a system until I knew what the pressures were.

Lots of stuiff can cause insufficient cooling besides a low charge.

My 2 cents.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

Listen to James and Mike. They don't call those low side gauge charge kits from Wal-Mart "Suicide Kits" for nothing.

Somehow get access to manifold gauges and monitor both pressures. Post pressures, ambient temp and vent temps here and we then have adequate info to start advising.

Good luck,

Thanks for all of the information. I was aware of the kits with the suction line pressure gauge and have heard of charging the system until you get a clear sight glass, but before I did anything, I thought I would pursue further and get an opinion more knowledgeable than my own.

Larry, I was unaware that these recharge kits had the nickname of "suicide kits." I will definitely remember that one! Since I do not have access to a set of high/low pressure gauges, I would rather have a trained technician take care of this and pay him a few bucks instead of paying big bucks if I try to do it myself and end up overcharging the system and damaging a component. Since it is still cooling well today (it is 94 F) I think I will leave things well enough alone until I hear the compressor cycling on the low pressure switch or it is not pulling the cabin temperature down quickly enough. Like they say, "If it's not broke, don't fix it." or the corollary to that "If it's not broke, it hasn't been fixed enough!"

One thing I must say though is that it is quite amazing that no charge has been needed since the system was recharged in 1999 when the sight glass cracked. The hoses, connectors and compressor for this vehicle must be very good.

The port that sticks out front below headlamp is the HIGH SIDE. It almost fooled me because I wondered why it would be placed in such a convenient spot ... easy charging I thought. Bzzzzt.

Look to the right of the engine block and down some and you'll see the low side port. It's a little tight to get to but not a major problem.

Good Luck!

__________________
-Paul-
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi

pmizell:

The port that you are describing adjacent to the engine block and down some is the port I was referring to. It has a black dust cap over it.

I will have to check for the high side port adjacent to the headlamp since I did not even notice that one.

Thanks for the input.

Bob, go to Northern Tool (Cary) or Harbour Freight (Capital Blvd) and get a set of manifold gauges for less than $75, or used ones on ebay, pawn shops, friends for less than that.

also buy a long thermometer and leave it stuck into the middle dash vent at all times to monitor. 41-48 degrees vent temp with 80-85 degrees outside is good.

BTW you want to charge into the low side port (line running to the compressor from the firewall). high side is the line going into the condenser (at the front of the car)

__________________
1993 Mercedes Benz 300D 2.5 205K (ex wife's)
1984 Mercedes Benz 300SD 320K (SOLD)
2004 Mercedes Benz C240 75K
1995 GMC Sierra 2WD 5.7L 188K
1983 Mercedes Benz 300SD 239K (SOLD)
1987 BMW 325i 220K (SOLD FOR SALVAGE)

609 Certification

Bob, Harbour Freight has 134a manifold gauge sets with hoses starting at $39.95. Get over to Capital Blvd. (not far from Leith MB).

They probably have a good long digital thermometer also.

These too items will help you service/diag/charge your a/c sytem. Instead of paying $70+ for a shop too do the same thing.

__________________
1993 Mercedes Benz 300D 2.5 205K (ex wife's)
1984 Mercedes Benz 300SD 320K (SOLD)
2004 Mercedes Benz C240 75K
1995 GMC Sierra 2WD 5.7L 188K
1983 Mercedes Benz 300SD 239K (SOLD)
1987 BMW 325i 220K (SOLD FOR SALVAGE)

609 Certification