Hi There,
I'm about to replace my A/C condenser, system currently charged, not leaking (condenser bent from accident). WIS states to add 20g of oil when replacing condenser.. why they just can't state that in actual ML and keep it simple just figures:banghead:
I know there's wiggle room and not meaning to make this a science project, but if we were talking water, I believe this would simply translate to 20 ml or .67 oz. I looked up the density of PAG46 and it's apparently .865 (water would be 1.0). Doing the math, this would mean 20 grams of PAG46 would be 23 ml or .8 oz.
Does this seem right? I'm thinking adding just shy of an ounce is all that's needed?
Lastly I've read that lubricating o-rings with PAG is a bad idea because it attracts moisture. I've also read it doesn't matter in real life and I'm kind of in that camp. Rather not buy a bottle of special refrigerant o-ring oil (or R-12 mineral) unless it really does matter.
It's best to lubricate the o-rings with the PAG oil you are using. The amount of moisture absorbed is insignificant and will be removed when you vacuum test the system. Do not install the o-ring dry as there is a chance they can be damaged or not seat properly.
You should also replace the dryer/receiver whenever the A/C system is opened. This should also take care of any concern you have about using PAG oil on the o-ring. Don't forget to add the recommend amount of PAG oil for the dryer/receiver
In different system logic are different to start with and lot of things on MB are getting "lost in translation" like typical pilot bushing for example.
I spend 1/2 of my life in metric system, 1/2 in SAE so don't even bother to figure out why it is done this way, or the other.
The weirdest logic I found is that all SAE cars do use metric spark plugs, while whole metric World is measuring pipes in inches.
Go to British Columbia, where cars measure speed in kph, boats in knots, land distance is given in km, while water dept in feet.
Go to delicatessen story to buy some cold cuts and you might find the price given in oz not in kg. Simply looks better this way
Coming back to AC oil, your calculation are correct, but I would not overdue it. It is the drier that holds most of the oil, not the condenser.
If you have a scale, it would be easier to dispense the oil, especially if you do not have any scaling on the bottle. Just subtract the required weight from the initial weight, and dispense till you get to the final weight on the scale.
Just like how a pro dispenses the refrigerant from a canister based on weight (1 kg for my car).
The training I had taught me that using weight is more consisten given unmarked or bulk amounts of oil and refrigerant (e.g. a factory or auto repair facility.) Everything is done by weight using a scale like this, kinda like when you're cooking.
Thanks all for the replies, just wanted to be sure I wasn't missing something and it's been many years since I messed with A/C systems (all R-12, 134a was just entering market). I do have a scale and just think I'll weigh it.
Weight is quick way to do the job, but I have been charging "quite a few" system by pressure and even older cars could freeze my elbows off.
Charging by pressure takes more time due the pressure changing a lot the liquid to vapor principals, but getting precision scale that can weight 30lb cost pretty money.
Than operating with 12 oz can makes it very easy both ways.
Thanks for the tip Kaj. I have 3 three 12oz cans and a small digital scale and that's the route I'll take along with paying close attention to pressure and ambient temps. It's been really cold here in CT so I've been putting this off until we have at reasonably nice day like in the mid 50's or higher - not that it matters terribly but at least I'll be in the right frame of mind to work on the A/C, lol.
And this just reminded me, I have the bumper along with a a lot of other parts off the car, but specifically the ambient temp sensor, which disconnected reads -32F on the dash. I have no idea if this will lock out the compressor but am thinking I might be well served to plug that back in for the re-charge.
Per my experience the bumper probe only gives you temperature on the cluster, while the engine computer has to have different probe, most likely mounted in the windshield gutter.
It cooled down nicely here in Vegas, down to 80F
Still coming from SF area, when I wear T-shirt, the employees at Vegas Costco wear sweat shirts and have gas heaters above the doors on.
The outside temperature sensor (B14) at the bumper is connected to the instrument panel. The instrument panel send the outside temp value to the a/c control unit via the K1 line of signaling.
Operationally, I do not believe the outside temp. sensor value is used for the control of the compressor. It is used to route the air (recirculating / outside) depending on the outside temperature automatically as well as some control over the blower speed. The idea is, if the outside temperature is high, it turns the recirculate mode on automatically for some time to cool the car faster.
However, in testing the refrigerant level and the performance of the system, you need the ambient temperature to check against the refrigerant pressure (low and high), refrigerant temperature, center outlet temperature at various ambient humidity levels. So it would make sense to connect the temp sensor for verification.
I observe the sensor readouts very carefully when driving fanless diesel on 114F desert with LA- LV traffic.
The climatronic was showing different temperatures on outside and engine than the cluster gauges.
I figured out they had to be dual sensors as at the era MB did not use dummy gauges.
Maybe because your a/c unit was not updated by the cluster as often, and/or it had intermittent communication problems (K1 error) in your cluster error list, and you did not know what the heck it meant at that time
It is true that in w124s or maybe earlier, the coolant temp sensor unit either had two sensors in one unit (4 pins) or two physically separate sensors. One for the a/c "klima unit) and the other for the display / engine control.
I don't have knowledge how the car wiring goes, but my experience tells about double sensors.
When you idle in park with front bumper facing the sun, the dash sensor can show as high as 60C, while outside temperature is 25 or so.
That sure would mess up AC program.
When I was taking 17 miles long grade in 114F heat at 80MPH, the climatronic was showing engine at 96C, while dash gauge was glued to 85.
I took it that 2 sensors are placed in different points, that is why they show big difference in extreme situations.
The temperatures even up when car come to normal cruising.
Kaj, I do not know which of your cars you are referring to (possibly the one you sold to Deplore from your description of no visco fan), and you have EPC to check the part numbers. Show us the part numbers for two different outside temp sensors (one for the dash, and one for the a/c unit) for your ex-car model year, and that will settle the issue.
I have not experienced the same thing Kaj. When I have checked the climate control data it showed the same outside temp as the screen on the dash. Same goes for the coolant temp. It matched perfectly to the temp gauge on the instrument cluster. Although I have noticed a delay when the outside temp changes (looking at the instrument cluster screen) and when the climate control outside temp changes. But there is no delay in coolant temp data between the two.
Because your Instrument Cluster communicates well with the a/c control unit. Sometimes people replace their a/c control units from some other car model year. The unit looks exactly the same, but it needs correct version coding to match the car system. If the version coding is not correct, K1 and/or K2 signaling between the I/C and A/C units may be disabled. and this can give lots of annoying a/c issues.
Yeah, I was referring to car Deplore owns now.
It is pre-lift, so maybe post lift have different sensors.
Easy test - park the car with hot engine and front facing sun and let it sit for few minutes.
The dash gauge should show temperature raising drastically, so compare what #2 on climatronic will say at the moment?
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