Puff

2011 E-350 S212 4Matic

I have topped of my R134a using a A/C Pro refill kit. The gauge is defective and I believe that I have over filled. Using the OBD II (Icarsoft) the Bar pressure data stream is reading about 14 Bar at 85F. Anyone know what the Bar pressure should be? No codes showing. The only symptom is that the engine cooling fan runs at high speed once the A/C is turned on.

Thanks in advance.

thefisch

That's gotta be a high side reading as 14 bar equates to 203 psi. Depending on the ambient temp you may be ok. You can find charts online like this one http://rechargeac.com/how-to/ac-system-pressure-chart

Personally, I would rather check with a gauge. I think most auto parts store will let you borrow one.

You didn't share why you topped it off to begin with. Did you vent refrigerator? Did it stop blowing cold? Did you take a reading before you added anything? Refrigerant doesn't leave the system unless there is a leak or component issue.

Mud

I hope this is taken constructively but the worst guess is to plug in additional refrigerant without knowing both high and low pressure side pressures vs ambient temp. These systems are very touchy on correct amount in the system.
203 psi in our current (hot) temps is on the low end of high (pressure) side so it would be good to know what the low (suction) side pressure is. I would suspect that would be higher than normal with compressor working harder. What's the compressor doing? Is it cycling a lot or steady on (meaning clutch engagement not just the belt pulley turning)
Looking at actual readings with gauges on both sides of the system can also help isolate possible issues at compressor, evap core and condenser, the big 3 of the system. Pressures equalize when off thru an orifice tube or expansion valve and These are very small sized tubes that can clog if there's debris in the system, result is uneven pressures and poor cooling. Also more strain on the compressor.
I've got a set of cheapie Harbor Freight gauges that have worked great for several years. Well worth the cost even for occasional use. I'm going to be using them tomorrow as a matter of fact on son's 99 civic work car. Unfortunately the compressor locked up so there's almost everything except hoses to be replaced . We can flush those. This touches on my comment on your car, you want to avoid things that can lead to compressor failure.
Anyway I don't want to sound like I'm ranting on about this, but really urge you to get the system properly checked. I agree there may be a possible leak somewhere and whatever you do never use a refrigerant with stop-leak. Almost a guarantee of future failure due to clogged expansion valve or orifice tube.

Puff

Thanks. I was hitting 80,000 and did some DYI, plugs, oil, cabin filter, air filter (had a good Indy do the trans fluid & filter) and thought to do a quick check of the low pressure with the A/C Pro kit. Adjusting for the temp, the low side was a tad low. I gave it the recommend 15 second trigger pull and the gauge when haywire. ( belatedly checked on the Amazon website for comments on the A/C Pro gauge and saw many comments about the gauge being crap).

I then used the Icarsoft to check the A/C data stream against the same setting in my 2013 E-350 W212 coupe and the Bar readings were very close. The A/C is working just fine. My concern arose about 2 weeks later when after taking a 600 mile road trip I noticed that the engin fan would run at high speed upon engine start and turning on the A/C. This does not happen in the coupe. Am I going down the garden path worring about the fan running at high speed at startup?

I think that I will take it over to the Indy and have the A/C serviced.

Mud

Some thoughts maybe ask the tech to check, I don't think you are off the garden path at all, good observation.

Fan on high all the time sounds like it could be in a fail-safe mode. It's controlled by the ECM with sensor inputs from MAF, ac pressure switch, condenser temp sensor (if this car has one), engine temp sensor and probably a few more. Worst case is issue with ECM but hope for the best. So the fan could be looking for specific signal and upon not receiving it, it goes into full blast mode.

I think that if the tech checks sensors and input ranges on vehicle specific scan equipment, he can verify go/no-go status of the various inputs. That includes checking the voltages or resistance at the various pin connections.

Good luck, I hope you post results of the visit for future reference for hacks like me!

Puff

To clarify, the fan does not run at high all of the time, just at start up and once-in-a-while throughout a drive. I use a Icarsoft OBDII MB II for MB and there are no DCT's logged in the system, and from what I can tell the Data Stream values are all normal.

Thanks again.

Charlie

thefisch

I always have to resist the temptation to check the pressure without a code or obvious problem. I used to be ocd about it on a previous car that had an issue. Checking the pressure, measuring temp drop, humidity, etc. I've calmed down since.

Mud

Ah my bad, I misunderstood the fan condition. That actually sounds normal. Anyway maybe a quick system check will yield all ok.