5634MG

I’ve always service my vehicles at the dealership but was just quoted over $900 to recharge the AC. It seems excessive even at the dealership or is that doable nowadays?

Recently, I had my 7 series’ freon recharged at my BMW dealer service centre and it was only $300, is it just a lot more complex on the W166?

juanmor40

I serviced the 2012 W166-ML350 back in Jan 2023 timeframe on an Express Oil Change & Tire Engineers franchise, and total for evacuation, and recharge of the AC refrigerant was US$120 + refrigerant difference = US$160 + plus taxes. At the time, I did the repair required myself but I needed to evacuate the refrigerant the "right way", so I took there. They quoted me US$120 to evacuate only. The recharge cost was only the additional refrigerant weight if it needed more than the amount evacuated.

There is nothing special about the W166 AC system compared to a Toyota. So the dealer is charging way too much.

Now the main question is: why are you recharging your AC system? For a 2016, it should be fine for this time. My 2014 E350, and the 2015 ML350 are still on the original charge, and, for living in Florida, they still cool pretty well. Do you think you have a refrigerant leak?

5634MG

Thanks for the info.

I’m not sure if it’s a leak, but the system isn’t blowing out cool or warm air when necessary and it’s making a hissing sound. They’re saying it’s low on pressure and the ac needs to be recharged as a first step.

I’ve actually never needed to recharge the AC on both my 2012 W221 and also 2009 W164 ever in their lifetimes, are these newer vehicles just more prone to issues like these?

juanmor40

https://mbworld.org/forums/m-class-w...ml#post8699414

That is what I did back then.

How did the dealer determine was low pressure? I do not like to open these system unless extremely necessary; therefore, diagnosis, diagnosis until confident of the next steps.

For example, if pressure is low, below specs, the compressor will not engage. If it engages, there is refrigerant, then is it enough? Only with pressure gauges, you can determine that.

Not sure if Canadian Tire/Parts Source still run the rental tool program

ygmn

if it needs recharge, then it leaks somewhere, and you will always have to recharge unless you find leak and repair that first.

you can tell its low by hooking up HVAC pressure gages to HI & LO side and checking pressures and checking for what proper pressures should be versus ambient temps and humidty.

5634MG

Thanks for all the info.

They couldn't find the leak so they added dye and said to keep monitoring on both my and their end.

The price ended up to be $650 or so, with 295 being a diagnostic charge so I guess the 3xx amount is reasonable for dealer work but on the line item where it states the customer issues, it still states the approximate repair cost of $900

They used to not have a diagnostic charge and would give us additional loyalty service discounts and lots of items on the house. Maybe new management wants to end this practice and have additional revenue because I've been seeing them hold lots more internal meetings the past six months or so

juanmor40

I would rent/buy the UV light and monitor the leak if it ever leaks again. You can then share your findings here, and we try to help you. Here in the US, I was able to fix it myself; however, I am not sure I would have been able to do it in Ontario as I did here in Florida.

John Ha

Since you say it affects both heat and cool, I'd suggest looking at the temperature doors that direct air through the appropriate areas in the cabin HVAC system.

kajtek1

Living in CA, I had to learn how to fix AC, even that was not known item when I grew up in Poland.
To summarize
-you can test AC with a scanner. It will show you high pressure only, but that's good enough for initial troubleshooting
-r134 cost about $10 per can, or $15 for can with dye
-you can buy cheap gauge at any auto store, when full testing manifold with gauges cost. $65 at Harbor Freight
-if system holds some charge, adding some REFRIDGERANT every couple of years would be normal procedure. Some system can hold for up to 10 years, but rubber hoses are not really designed for that.
Bottom line, even if you buy tools you can have the system refilled for less than $100. Good scanner those days run $60 if you don't already have 1.

John Ha

Just wanted to mention that most of the chain auto stores loan the gauges and vacuum pumps so you don't have to buy something.