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I have C180 2013 coupe. AC act abnormally. When I park more than 15 hour. At first start AC will not run and it has hot air blow for 5 minute then AC turn on and act normally with cold air.
If park less than 15 hour , it work properly. I so wonder what it cause.
I change new AC compressor, Climate control unit. But it still not solve. Anyone experience this and solving please suggest.
I worked on my ac recently. I hardly ever use it and when I did go to use it the first time this summer it was blowing hot air. I wrote a thread all about it here: https://mbworld.org/forums/mercedes-...ctions-do.html
Using my Foxwell scanner allowed me to see what the ac was doing, if it was turning on, shows the refrigerant pressure, shows the evaporator temp etc. Then I bought an inexpensive refrigerant hose w/gauge which showed me the low pressure line pressure with the ac off and then on. I ended up putting around 1/2 can of R 134a in and it now works great.
Do you have a scanner can can show what the ac is doing and check for any faults in general? I would look at what the refrigerant pressure is reading with the ac off then on, see if its reading low and then has to build up. I have very little experience with ac systems so im just guessing.
Thank for you reply & suggest.
Mine case might different. It won't blow out hot air all the time. It just 5 minute if park > 12 hr. If parking less then 12 hr. It work normally. So, if using car everyday, it run perfectly. But will happen only parking for a long period.
I understand what you are saying the issue is, takes awhile for the ac to start blowing cold air if the car hasnt been driven for awhile.
I was thinking it may be something as simple as the refrigerant is a little low. Or may be an issue with the blend air doors not opening right away.
Do you have a Mercedes specific obd scanner? I hardly ever use mine but for the few times I have used it i feel it paid for itself.
You will be able to see if the ac compressor is even turning on or if there is a delay. Can see the evaporator temperature, if it is getting cold but still blowing hot air that may mean an issue with the blend air doors. Then you can see the refrigerant pressure, see if its lower than it should be.
Then use a gauge to check the low side pressure, see what it reads when the ac compressor is of, then on. With mine the low side pressure would drop to very low when the compressor was on.
@panjap Excellent trouble shooting routine from @TimC300 !
I was thinking blend air doors also. The sealing foam begins to deteriorate after many years and becomes sticky. Other elastic components begin to get stiff. The actuators begin to leak a bit.
I understand what you are saying the issue is, takes awhile for the ac to start blowing cold air if the car hasnt been driven for awhile.
I was thinking it may be something as simple as the refrigerant is a little low. Or may be an issue with the blend air doors not opening right away.
Do you have a Mercedes specific obd scanner? I hardly ever use mine but for the few times I have used it i feel it paid for itself.
You will be able to see if the ac compressor is even turning on or if there is a delay. Can see the evaporator temperature, if it is getting cold but still blowing hot air that may mean an issue with the blend air doors. Then you can see the refrigerant pressure, see if its lower than it should be.
Then use a gauge to check the low side pressure, see what it reads when the ac compressor is of, then on. With mine the low side pressure would drop to very low when the compressor was on.
Thank you Tim for you suggestion.
I test when I park 18 hour up. Then this event happen . However, it blow no cold air <5 minute, then I heard an injection sound then air cold flow. I suspect that compressor work after 5 minute pass.
Then for making sure my idea. I test it again by going to the air-con shop. Fortunately shop is so close to my house. He use refrigerant pressure to check my compressor is work or not. Yes, it won't work in first 5 minute , then after that, it work perfect. Unfortunately he has no any diagnostic to check more.
This problem won't occur if I daily drive (no static park for >18 hour).
My guess , it may come from AC pressure valve problem and when pressure reach its limit then it order compressor to work. I will go to anther air-con shop and explain them on this. Will see how they may solve it.
I like to fix things myself which is why I got an OBD scanner that works with Mercedes vehicles. Then I study the MB repair manual to see how specific things should work. From personal experience I dont like anyone working on my car except the MB dealer and they are very expensive. Like you explained even the ac-shop you went to isnt able to do much with Mercedes.
I would get an inexpensive Launch Mercedes obd scanner so you can see what the ac system is doing.
When mine was blowing only hot air I noticed the refrigerant pressure was showing at 1.7 bar. And according to the manual this is right at the min limit for the compressor to turn on.
That specific pressure sensor is at the condenser at the front bumper.
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