Filling AC system
 

Having replaced the evaporator I've vacuum tested the system and all is OK so now I need to fill it with freon (R134).

Is this a job I should leave to a professional? If so should I get the system flushed before filling?

If it's something I can tackle myself do I need any special equipment aside from the vacuum pump and the little connector with a gauge? Can someone give me the key steps or direct me to some instructions? The book says add 40cc of oil if you replace the evaporator.

Thanks again,

Peter

p.s. the car is a '99 E430

If your old evaporator was leaking freon, then it was most likely also leaking oil. Which means you really have no idea how much oil is presently in the system.

If you want to do this properly, you'll need to remove the compressor and drain/measure the oil present. The amount of fresh oil you add to the system will be dependent on the amount obtained from the compressor. The vehicle was factory filled with ND-8 PAG oil, so use the same to refill (MB # Q 1 13 0001). And since the car is 5 years old, replace the receiver/drier.

All the information you need to service this system, including oil fill values, can be found at www.startekinfo.com. Access charge for 1 day is now $18.00

Most all of the same information is available for free at www.acsource.com.

Since this is a system that was originally 134, there should be no need to flush the entire system. There is information on that site that gives an idea of how much and what kind of oil to add when replacing a given component. For instance it is probably about 2 oz. of oil that was lost with the evaporator replacement. There are three different weights of PAG oil, so you will need to find out which to use.

Yes, you should indeed replace the r/d since the system has been seriously opened up. Then you will need to evacuate, preferably in warm weather or with major components artificially warmed up to summer weather temperature in order to boil out the moisture during the evacuation process. Evacuation should be done with a good wet vane pump.

Then charge properly with gauges in place.

There is probably an auto air shop in your area that could evacuate and charge the system for you at a reasonable cost. You have accomplished the really expensive and tough part of the job. Congrats for that.

Good luck,

Sorry. That should be www.aircondition.com for auto a/c info.

Have a great day,

Larry and JGL1 thanks for replying. Yep the r/d has been replaced, AutoZone loans the vac pump, manifold and gauges for free so I'm tempted to try to fill the system. Maybe I should resist?

I looked at www.aircondition.com but didn't see any details about how to fill, am I missing something?

Thanks again,

Peter

If you don't have understanding and experience with refrigeration systems, I would strongly suggest that you do some reading and get some coaching. If you do understand refrigeration, then by all means, connect the gauges, evacuate and charge.

Good luck,

I would have to disagree with Larry regarding his recommendation of aircondition.com. The site is essentially a bulletin board, comprised mainly of commercial links and no subsections dedicated to Mercedes-Benz. For accurate refrigerant oil refill values for each component of your vehicle's A/C, I still recommend startekinfo.com.

Your A/C system was equipped with ND-8 PAG oil, which has an ISO viscosity of 46. It must be stressed that correct refrigerant oil level is important: too little shortens compressor life, too much reduces cooling efficiency.

Have a look at this article regarding compressor failure and evacuating and recharging a system:

www.babcox.com/editorial/ic/ic50350.htm


If you are interested in learning more about A/C service procedures, you might want to consider the self-study training programs offered by the Mobile Air Conditioning Society:

http://macsw.org/store/dept.asp?dept_id=2

The MACS Refrigerant Recycling & Service Procedures Training Manual can be downloaded, free of charge, from:

www.macsw.org/macs.asp?mfurl=certify.html