MegaSack DRAW - This year's winner is user - rgwb
We will be in touch
Mercs aircon was making some noises end of last year - sign that it was low on gas, but it was working (just).
Move forward to now and the system does nothing - no cold air, no noises, so I took it to the local Mercedes specialist as I was off work for a regass and they told me on the condenser had a leak. I though that was a bit odd as I had a receipt in the service history for a new condenser back in May 2015, £350 for the part, £100 fitting (both +vat) and £100 for the re-gass. They showed me a dark patch near the bottom through a hole in the slam panel that looked like a leak and quoted >£500 for a repair.
There are a few other jobs I want to do on the front of the car including give all the suspension bushes a check so I decided to do it myself (as the system was now empty) and have a good poke around the car while the bumper was off and look for any other jobs that might need doing soon as I prefer to fix things before they are critical. I ordered a new condenser for £116 (OEM manufacturer on offer not a cheap pattern one).
The condenser is an odd design with a metal pipe attached to the side that then runs to the bottom with another connector to plumb into the car pipework and houses the pressure sensor. sure enough around this connector it's a bit gunky with what looks like yellowish fluid (presumably the oil and UV dye so will get my UV torch out later)
On undoing the pipes to the condenser a load of pressurised gas came out which surprised me as I expected it to be empty.
Could there still be a slight leak but not enough to fully discharge the system? Is there some kind of valve on the condensor which closes if there is a leak? I have seen water radiators to maybe only leak once up to temperature but expected a gas system to just fully discharge as soon as there was a hole. I'll put the new on in anyway but curious now so I guess I could do a leak test on it now inner tube style.
Once the pressure in the system reached a low enough level, the leak will have resealed. The propellant in a/c is a liquid when stored under pressure.
It's filled with refrigerant probably r134a as you aren't getting it sorted under warranty.
R134a is a great gas as far as walming the planet goes so please don't vent it to atmosphere.
Take it to a good independent and get them to recover any remaining? Refrigerant and pressure test it, then if the leak is on the condenser it's a straight swap and pressure test. It then needs the nitrogen used for pressure testing released and the air vacced out, then recharge with the correct amount of refrigerant.
Cheers DB
Reason for it stops running despite having some gas in it is due to the low pressure switch which stops the compressor running and damaging itself.
Before breaking into an air con circuit it should be vacced down and any gas recovered. It’s both bad for the environment and your health to just crack a union open with out doing this 1st.
I must say I'm as pikey as they come when it comes to vehicle maintainance but venting Aircon refrigerant to Atmos is even below me.
It's done now though .
But equally I'd go get what's left pressure tested with die once the condenser is changed and get the rest of system checked before filling with refrigerant.
If you were in the USofA, you could just pop into the supermarket for a can or two of R134a to top it up when you're done nipping up those joints to your new condenser.
https://www.walmart.com/c/kp/r134a-recharge-kits
Used to be able to buy top ups in halfords, you'd still have air in the system if not vacced out which leads to crap performance and eventually failure
Just had ours done on the Subaru. £600+... !
Thankfully, due to full Subaru service history it was mended for free as good will gesture despite being out of warranty.
The Merc dealer should have left the system empty, they are not allowed to refill when the equipment has detected a leak (due to it being so bad for the environment)
I'm having a run of good luck with the air con in our Civic. It broke a couple of years ago, changed a relay, didn't fix it, got it regassed at KwikFit, didn't fix it so got a refund under their guarantee, then bought a shim pack and reshimmed the clutch on the compressor (didn't even need a shim, just took the existing one out) Honda would have charged for a whole new compressor and re-gas at over £600.
Then it broke this week, just fixed it by swapping the new relay back to the original 🙂
(So if your air con works briefly before cutting out, read up on the almost free option of reshimmed the compressor clutch, its relatively easy albeit fiddly.)
I'm well aware of r134a/tetrafluoroethane hence my concern and not going any further but remember all working car systems lose gas, that's why they need re-gassing every couple of years and if you use electronics or pipe freezing aerosols then you are also releasing it.
It will be r134a, doesnt matter if it's warranty or not. R12 is no longer used and Mercedes (and others) refuse to use the new gas as it is flammable. They are trying to develop CO2 based systems but these need much higher pressures and car AC is already crap enough at 100-200psi.
The system already has a visible leak in the high pressure side big enough to let oil and UV dye out so I don't think it is unreasonable to suspect the system cannot hold gas pressure. Got the UV torch out this evening and lots of dye around the bottom connector and pressure sensor and also dye exactly where the garage pointed to on the edge of the main matrix where it joints the tube at the side.
The other thing I did wonder was whether it would be nitrogen from the leak testing. Tetrafluoroethane only has a slight odor and it was only a split second or so, so maybe it's hard to detect but my face was inches away and right underneath the pipe so I would have thought I would smell something. But surely the nitrogen would all leak out too?
gas leak felt like someone blowing on my finger and as a guess way less than 10psi but I was expecting nothing. Certainly not in the 100+ PSI range but not the nothing I was expecting.