BetterDaze

Hello friends, in 2021 I had my car converted to r134a and the shop added dye to check for leaks after recharging the system. The A/C worked but only slightly as my fan speed slider was broken. My car broke down and sat another year shortly after and I’m just now getting back to fixing the A/C. Is it likely all the refrigerant evaporated?

I replaced the fan speed slider today but only getting hot air and what feels like slightly cooler air from the vents. The climate control buttons seem to only change the location that this air comes from and I’m not sure if the temp wheel is working at all…confusing controls

Right now I know my A/C compressor works and all my buttons function but may have a leak somewhere. What would you do next? the conversion was expensive and I’d like to avoid a shop on this one.

dolucasi

I would first but a can of refrigerant and charge the system from your auto store. Buy the ones that have a pressure gauge on, they are 40-50 dollars.
You will also find out if there is enough refrigerant in the system.

bbirdwell

Put a set of pressure gauges on it. With outside air temperature of approximately 80° f, you should see somewhere around 45 PSI on the low side and approximately 200 on the high side. Static pressure with the compressor off should read somewhere between 70 and 90 PSI depending upon the outside air temperature.

LauraS

My advice would be to bite the bullet and at least have the refridgerant level and performance of the entire system checked and have it tested with a dye which will show leaks. No sense dumping gas into a system that will only leak out and pollute the environment.

190Efan

I have to agree with Laura on this one. The warm air indicates to me that the r134A has likely leaked out so that means there's a leak that caused that to happen. Putting more r134A in will be futile because it will also leak out. It's important to determine where the leak is and fix the leak before adding more r134A. The best way to do that is with the dye in the system. Unfortunately, owning a Mercedes-Benz is not for the financially faint of heart. I've not been on speaking terms with my bank account in years. However the magnificent reward of driving such a magnificent machine and having it look magnificent on show day is more than worth all of the aggravation and financial heartache to get to those points. That's how I have it rationalized.

LauraS

My 1990 190E still has the original R-12 and blows ice cold although it has rarely had much use where I live-perhaps 2 or 3 days a summer. I regularly ran it anyway just to keep gas moving and so far it seems to work. AC is one of those items that requires a professional to service properly in my opinion.
I was at Canadian Tire store today and out of curiousity saw that cans of AC stop leak is being sold as well as a dye kit to test for leaks so that may be worth a try. I stand by my initial advice to seek a professional to avoid damaging the entire system.

BetterDaze

Thanks all,

the shop already did the initial refill and dye add. I only go to them for things I for sure can’t do myself and I’m picking up where they left off. It’s fun and saves money!

Honestly spent a little over 1/3 of what I was quoted to restore it to its current state though it took a few years. My philosophy is that cars are often the most expensive thing we own and it makes 0 sense to know nothing about it, most mechanics WILL rip you off , I’ve had many blatantly lie to my face. I do have 2 I trust but you have to wait and even then you must respect their labor rate lol. You should at least enjoy the car if it’s going to be a persistent expense

I found the leak but would like to know where else to look. There is nothing around the compressor itself or any visible lines but what is this component? The gauge is reading 0psi

dolucasi

That might be the dryer connector. Maybe take a daylight photo.

If a leak causes the pressure to go down to zero in short order, you know it is at the high pressure side of things. I have had a low pressure hose leak for 4-5 years now. In my case the hose that goes from the condenser to the engine and back to the compressor has pin holes in it. Have not had to refill the AC at all even though I do not use the AC much, but when I need it it is there and working. I wrapped the hose with some sort of sealant tape and the the leak is much reduced.

The return hose of course is NLA at the dealer. I do have an aftermarket one in hand and will replace it but that would require the AC system to be discharged, captured, etc. So since it is not broken I carry on for now.

Looks like yours will be an easy fix since the system is already discharged. Perhaps have a qualified AC mechanic fix that and give you some sort of warranty for future leaks.

BetterDaze

Thank you dolucasi, quick chat with my indie and they said all my fittings are new. I think I should be okay to just tighten this and refill. Great news, I should have time this evening to try

190Efan

If the dryer connector is found to be at fault, I would suggest trying the MB Classic Center to see if they still have the part. They have better parts availability for the older cars than the MB dealerships do. You might also try www.adsitco.com. They also have alot of unavailable MB parts. I do agree with Dolucassi that this is likely a job for an A/C professional with older MB experience. You really need to determine where in fact the leak is and the best way to do that is with the dye. Just throwing parts and hoping that you guess right can get very expensive and not solve the problem in the long run. My car is like Laura's and still has the r12 system due to my desire to keep my car as original as possible. I've had to add Freon a couple of times but that's been it. I hope no more because Freon is now impossible to obtain. It's also crucial that once you get your A/C running properly that you run it on a regular basis to keep it functioning properly. My engineer father always taught me to run it at least 10 minutes at a time even in the cooler months for that purpose. Having been raised by an engineer has helped me enormously as far as keeping my cars properly maintained, knowing what work is actually needed and what isn't needed which has also saved me money. Maybe you should contact the BBB to find a reputable A/C specialist in your local area.

BetterDaze

I tightened that fitting and filled the Freon until the gauge was green. When I turn on the AC I set my phone to record the compressor and didn’t see it engage at all. Am I supposed to see it kick out or something?

Im getting cooler air from center vents but persistent and high heat from the vents near the windshield and doors at all times….years ago I replaced the heater valve under the leaf catcher and I possibly installed it backwards but I don’t recall if I ever corrected it smh

lsmalley

Definitely go check the heater valve. If coolant is flowing through the heater core, it won't matter how cold your a/c gets, you'll still get only get warm cabin temps still. Also, it sounds like your vacuum pods are not functioning if you are getting air from all vents with only certain diverter functions active. One major upgrade you can do is to get rid of the r134a and use r152a, regular Dust Off. That way you can always vent your system out and just replenish it whenever you need to work on your ac system without worrying about the ozone (or it being illegal) and also, it's dirt cheap. You can get like six 16 oz cans from Costco for like $20. You don't need to add or do anything other than to get the r134a out of your system and just refill with the r152a. One of the best upgrades I've done amongst a few others and now I literally get ice cold air on a 115 degree day.

190Efan

You should be able to hear your A/C compressor clicking on when you turn your A/C on. Since you're getting some cool air it must be working in some capacity which means that the issue is likely elsewhere in the system.

BetterDaze

I just now saw the conversion sticker my indie left and the capacity for the system is 2.1 pounds and the gauge is reading over 3(still in green range). It is likely overfilled and im going to leave it alone and let a shop drain it all out.

this is the orientation of my heater core valve Can someone compare to their own? I have heat coming out near windshield no matter what button is pressed. The bottom of the pick is heading to the front of the car

dolucasi

I believe that valve designed in a strange way but probably with good reason. If there is no vacuum on the pump it is on. If there is vacuum it turns off heat.
Hopefully my memory does not fail me. So you can attempt to apply vacuum an see if the hot air stops.

BetterDaze

Got my car back from indie and we have ac coming from center vents but at the same time heat from windshield vents. The only button giving me cool air is the “windshield icon” which triggers the state I described above.

the AC button itself will not trigger the compressor and only allow warm heat from center vents.

what can I test next? I believe either my ac controls unit is bugged or I have a leak somewhere in the pink pods system

dolucasi

Hi Betterdaze, have you already tried my suggestion? You can hand activate that hot air valve to see if there is any change. The lever on it is exposed. If you can make the hot air turn to cold by manually activating it then you know the pod is not getting the vacuum (or getting vacuum when it is not supposed to).

Hot water can only get passed that valve. If hand activation does not change anything, the valve is busted. If it does, than the the controller maybe busted or the vacuum line is busted. Also you can test your system by unplugging the vacuum line and looking for vacuum or absence of it by changing the settings. This will test the controller/switchover valves.

moose00015

You can test the pods for leaks with a vacuum hand pump. The switchover valve is behind the glovebox. This link will tell you which line goes where. You pull vacuum on all of them and the ones that don't hold vacuum indicate a bad diaphragm in that particular pod. You can get replacement diaphragms from George at Performance Analysis. He'd be able to tell you if he has the one that is necessary.

Here's a on the replacement process.

Hope that helps!

190Efan

I'll be interested to see where this goes. I've begun to notice my A/C beginning to behave in a similar manner.

dolucasi

I suspect eventually most who convert to R-134A will experience same fate as mine. The high pressure hose between the condenser to the drier unit(?), the long one that is also attached the the engine starts "sweating" refrigerant. It is as if it develops many tine pin holes. Mine did anyway. The leak is very slow and takes a year or two to sweat out. So check that hose which is visible from under the car right by the roll bar. Here is picture I took a few years back. Notice the droplets on the hose. I have an aftermarket replacement, dealer ones are of course NLA.
I suspect the R134A conversion ends up with higher pressure in this line perhaps. It is an odd failure mode, but very easy to see. That is nice,

BetterDaze

Sorry had a busy week.

I suspect it is the climate control unit itself, after playing with it and feeling the air I don’t think any of the buttons actually work except the defroster(windshield Icon) which is when I feel the windshield heat at the same time as cool air center vent air.

feedback from indie was that the compressor works with that button activated but solely pressing the ac buttons does nothing. They have some spares I can try which is my next step

BetterDaze

I discovered that if I press my AC buttons before starting my car it will blow cool air from the center vents with the arrow up and AC buttons pressed immediately upon starting but eventually stop.

I was enjoying it until it eventually I hear a click and it stops blowing completely. This is repeatable and I believed it did not work at all initially but there has to be some additional fuse or electrical component I missed and can check outside the fuse box ?

190Efan

I was always taught to NOT run my A/C before I start my car or try to run my A/C after I've shut the car off because it puts a strain on the entire system. You've probably blown a fuse doing what you've been doing.

BetterDaze

maybe I should better explain the scenario since it’s been a while…


AC system fully converted to r134 a couple years ago and the system was deemed working fine by my indie. The issue was the vent selection buttons didn’t actually affect location the air comes nor the temp wheel. I can get AC from my car but only via the defrost button which also gives full blown heat at the same time. Up/down arrows seemed to do nothing and I tried a used AC control module it it functioned similarly so I gave up trying to use it…fast forward to a few days ago now


car sat two days…I start it and feel ice cold air coming through and noticed that I had probably pressed the up arrow button and ac button last time I was in the car by accident since I do use the fresh air vents when too hot.

I let the car run with up arrow pressed and ac button pressed it got cold in the car, no heat from windshield either. I initially believed the arrows didn’t work at all but it does and after a couple minutes it started clicking inside the dash and it just stopped completely.

I then turn on the defrost and the ac kicks back on but again full heat at the same time, I press up arrow again to try and trigger the AC again without the heat but it did not work this time.

It only seems to work when i first start the car and then die out after so long. Something in there is working when I first start the car but getting tired or losing voltage, there has to be a fuse or relay outside the fuse box to check

I know what you mean 190efan but this is the only way to diagnose it right now and I discovered this on accident

190Efan

You don't want to be engaging your A/C compressor before you start your car.