i agree, recharge the system!!

Was the engine running when you took the measurement? What was the ambient temperature? And was the A/C engaged with temperature settings to max cold? What are you using as a gauge? Please tell us you're not using one of those recharge cans with the built-in gauge. That only tells you low side pressure, which is only half the picture - you really need to know high side pressure. Check both high and low pressures with a manifold gauge and report back here with the readings as well as ambient temperature so the experts can chime in.

Charging by weight is preferable, but it is also possible to charge by pressure using the manifold gauge.

Again, it really seems like your charge is just low. Hang in there...

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Thanks MBDoc for your input. How do I discharge the system on my own properly? Also, what is the correct weight of 134a I have to use in a '99 E320? Also, can i use ENVIRO-SAFE ES-12a instead? If so, how much weight of Enviro should i charge into the system?

Do a search on alternative refrigerants - the bottom line is that they are actually blends of other refrigerants, and each individual component leaks out at different rates which changes the overall blend. So when you're low you will have to discharge and recharge all over again.

What's wrong with R134a? It's really cheap, about $7 a can. Your system probably takes 2 to 2.5 12-oz. cans. Maybe the experts can chime in here as to the exact weight, again I usually charge with the gauges and not by weight.

Approved equipment should be used to properly discharge the system; it is illegal to just "vent" it to the atmosphere. So unless you have the correct equipment, your best bet is taking it to an A/C pro.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Dear gmercoleza, the question is: HOW TO discharge (given that one is using proper equipment)?

Follow the instructions that came with the evacuator.

Yes, just hook it up and turn it on.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Guys, you're all very kind, but I'm less mechanically inclined than you think:

-What evacuator?..where to get one? (Can't i just use my air compressor?)
-Which side do I hook it up to? Low pressure or high pressure?
-Does it hoop up the same way (same spot) as the refrigerant can will later?
-Is the evacuator a pump, or a blower?
-When I flush, where do I pump air in, and where will everything escape out?
-Do I need to flush, or evacuation IS flushing?..
-also, by charging enough weight of refrigerant, will it guarrantee full pressure,
or pressure and refrig. amount is two different things and are done separately?

Thanks for your patience.

Hey OnlyBenz,
These guys have been trying to be nice to you, but your last answer makes it very clear to everyone that you don't have the slightest idea of how to service an AC system, and don't have the specialized tools that are ABSOLUTELY necessary to service the AC system. Take it to an AC specialist, or you will end up costing yourself several thousands of dollars.

Regards,

__________________
Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C

Richard,
Why the arrogance? I do acknowledge that the guys are nice to me, and I don't show them any disrespect. I will be servicing the AC system on my own, that is why I'm here, to gather information. It will not cost me thousands, as it will not go to an AC profesional. If taking it to an AC pro was my intention, I wouldn't be on this forum.

An evacuator is a special pump. Expect to pay $400 or so for one, plus the recovery tank that you'll need. Besides removing the refridgerant from the system before doing work, it also removes the air when you're ready to recharge.

The evacuator does not flush the system. That's a separate job, which requires dismantling the connectors and flushing fluid through the lines, evaporator and condensor. You don't flush the compressor, but just remove it from the car and drain any oil.

It would seem that you would be better off with just a set of gauges. This can be had for about $100 or so, and you'll need it in addition to an evacuator anyway. If you haven't done so already, get the climate-control troubleshooting manual for your car. It has the pressure charts for the system.

Hi Only Benz,
I wasn't trying to be arrogant! I was giving you my best recommendation based on the questions you asked in the previous post. In order to evacuate, flush, and recharge the AC system you will have to buy:

1. Manifold gauge set

2. Refrigerant recycle/reclaim unit, around $500 used on Ebay, or over 2K new.

3. Refrigerant tank to go with recycle/reclaim unit, they are a special tank with three valves, at least that's what my Robinaire unit takes.

4. Flushing solvent

5. New O-rings for system (recommended for all fittings, required for connections that have been disturbed.)

6. New receiver/dryer, required when system has been opened.

7. Fresh lube charge

8. Fresh refrigerant

9. Some way of measuring new charge, measuring by weight preferred but requires special equipment.

If you want to play with your AC system, that's certainly up to you, but if you fail to observe the necessary steps you will contaminate the atmosphere, your car's AC system, and most likely take out the compressor in short order. If you "want to do it yourself", you will have to spend more money on the REQUIRED equipment to do the job than it will cost to take it to an honest independent AC shop.

My recommendation comes from over 45 years experience in the business.
Once again, I'm NOT trying to be arrogant, just trying to advise you the best way I can.

Good luck with it.

__________________
Richard Wooldridge
'01 ML320
'82 300D 4.3L V6/T700R4 conversion
'82 380SL, '86 560SL engine/trans. installed
'79 450SL, digital servo update
'75 280C

I think I've come to a decision on how to proceed. Here is what I'm gonna do.
I've checked my compressor, it turns on and never shuts of, and it's dry, free of oil stains etc. My blower is good, as the force of incoming air is not weak.
My condenser should be good, as i get cold air on the passanger side. My control panel should be good, as air is coming from the proper outlets as switched around etc. I found some oil stains on some of the rubber hosing. So:

I have bought these brand new Benz parts (cheap on ebay!) just in case:
-hosing and o-rings for both low and high pressure side
-heater douvalve
-receiver/drier
-expansion valve
-cabin air filter

I will take the car to an AC Pro, have him replace the above parts (and pay labor only), then have him evacuate and re-charge.

My qestion is: Is it legal (in Canada) to perform evacuation and re-charge WITHOUT a leak-check?

I've been waiting to see how this story will end. Only_benz, I admire your determination, but you're throwing money at the problem when your intention is to save money. The wise thing to do would be to have the system topped off and add some dye. Drive the car for a few days and re-check for the leak. The money you spend paying a professional to do this will be less than you'll spend replacing parts that aren't bad. The members on this Forum have given you EXCELLENT advice. You'd be crazy not to take it.

Indeed, you need to check the pressures before you even consider evacuating the system, and add some refridgerant (and perhaps dye) if it's low.

You're trying to kill an ant with a sledgehammer here. You could be just a bit low without having a leak big enough to worry about.

As to whether you can evacuate and recharge without a checking for leaks, that's pretty much physically impossible. Evacuating itself will do the leak-check for you. If it won't hold a vacuum, there's a leak and there is air in the system due to that leak. You do not want to mix air and HFC134a in the system, as the refridgerant is known to be combustible when in the presence of air at high pressure.

As I said before, get the climate-control diagnostic manual (I paid about $50 for my copy), and a set of manifold gauges from any auto-parts shop. Don't just throw money at it. But definitely replace your air filter. I replaced mine the other day, and it was black as my heart.

But of course, it's your car. I'm just telling you what I would do if it were mine.

Note: If you do take my advice and get the manual and gauges, the low-side port is the one on the driver's side in the engine compartment, kind of between the brake master cylinder and the ABS controller. The high-side port is behind a small cover just in front of the top driver-side of the radiator. You'll have to remove the inside grill, just in front of the electric fan set, to remove this cover (no tools are required).