Independent Renault Forums banner
Cancel
Create thread New Garage Forums

A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp) ( Solved )

Tags
131hp 19dci 96kw a or c pressure renault scenic sensor solved test
Jump to Latest
14K views 35 replies 3 participants last post by  Dainius Daujotas  
D
#1 · (Edited by Moderator)
Hey. So I set to repair my A/c system and its been a bumpy ride... But maybe just maybe the last thing I need to do is replace the A/c pressure sensor. At least thats what I gather from fault codes and a lot of google. Thou I still would like to test it before I go out and buy a new one. Is there a way to test it? Is it safe to test? I read that I would need to remove the negative battery terminal? All information would be helpful because more or less Im quite new to cars :D. Ty
 
#2 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

These sensors screw out..
Not come across any info explaining how to really test them,
Its usually done with Diagnostics, if certain the AC is full of gas, and still reading little or no pressure, then it points to the sensor ..
 
L
#3 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Post the actual aircon related codes you refer to.


How did you retrieve that code? (scanner brand) ............. what was the original problem and what has been done to make you say you had a bumpy ride?



Basically - you cannot fill the system if the pressure sensor isn't working properly (or very close to properly) - the pump is disabled ................. as a result if you can say that pump is kicking in then chances are you have at least some refrigerant in there and sensor is probably working ok


Engine off and ignition on, your scanner should read around ambient temp pressure on the R134a graph - 10 to 20 C around 3 Bar.


To remove the pressure sensor you must first remove the refrigerant in the system else the sensor will get launched to high heavens when you unscrew it
 
D
#5 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Adding some info : The system was empty when I started, went to specialists they filled it up, turned A/c on, nothing. Was advised to go see a electrician, so I did.

He hooked the car up and pulled up the faults(photos included Bosch ones)
Tried resetting the pressure one(or smth like that not sure) but it came back up, so he checked if the ac system had gas left (Was empty)/ And I just left .

Went back to the Ac ppl, they found a leaking hose in front. Changed it. Filled it up with gas and same thing, not working ,,Go see a electrician,,
So I did, just sadly it was ~6pm on a friday so only thing my eager self found was a backyard Russian style guy with a overweight friend? son? I have no clue.. Anyways they pull up the faults (Photo included)
In a lot of words tells me ,,Im fked, the system is too, everythings broken, better off buying a new car,, More or less.... Anywho I didnt take him serious but I did think the system was actually empty again, so I went back to the Ac ppl, they hook up the thing, check the system and there is gas there. So Here I Am. And yes... I won't touch the pressure thing.. Thanks
 
L
#8 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Dainius Daujotas said:
Wait, so its alright to pull it out? Because I also read somewhere that there is smth there to prevent the gas from leaking out(Correct me if Im wrong ofc)
Edit: Also, did my long post with the explanation not get through?
Click to expand...
Looks like its ok to pull out then yes based on what Ours just said. Question is if you have to.


No you long post never made it
 
D
#9 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Ok... Here I go again.

Starts off with me going to the A/c ppl, them filling my system up, we turn the A/c on, nothing..( I think the compressor wasnt even kicking in(Could be wrong here), but they just told me to go to a electrician, so I did

Went to one he hooked the car up and pulled the faults up( Photos included;- Bosh ones)tried clearing it I believe but it came back up, he hooked the car up to a pressure thingy to see if there is still gas there(Empty), and thats where I left.

Went back to A/c ppl, they did some testing back and forth and found a leak in a pype(the rubber one that has 2 metal ends, one goes into the thing where the pressure sensor is I believe). Went out bought a new one(was a damn pain finding the correct one as there are like ~20 variables :D). Brought it back to them, they swapped it, filled the system up, we turn the A/c on... Nothing. ,,Back to the electrician you go,, - they said.

Sadly it was a friday evening ( thought I just needed to clear a fault for the system to restart). The guy that I went too was a Russian decent type kind of guy with a obese friend with a Asus Tablet. Anyways, they hook the car up try clearing it... Nothing. Goes on a 5+ minute rant of how I'm fked, my car is fked, the A/c system is DEFINTETELY fked and it has no gas. I go into a small sad/angry panic go back to the A/c people, they hook the car up, says pressure is there, all good.

And here I'am not rly wanting to spend more money on this, hoping to draw the good card and all of this being the pressure thing. HELP :D
 

Attachments

L
#10 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Dainius Daujotas said:
Ok... Here I go again.

Starts off with me going to the A/c ppl, them filling my system up, we turn the A/c on, nothing..( I think the compressor wasnt even kicking in(Could be wrong here), but they just told me to go to a electrician, so I did

Went to one he hooked the car up and pulled the faults up( Photos included;- Bosh ones)tried clearing it I believe but it came back up, he hooked the car up to a pressure thingy to see if there is still gas there(Empty), and thats where I left.

Went back to A/c ppl, they did some testing back and forth and found a leak in a pype(the rubber one that has 2 metal ends, one goes into the thing where the pressure sensor is I believe). Went out bought a new one(was a damn pain finding the correct one as there are like ~20 variables :D). Brought it back to them, they swapped it, filled the system up, we turn the A/c on... Nothing. ,,Back to the electrician you go,, - they said.

Sadly it was a friday evening ( thought I just needed to clear a fault for the system to restart). Was a russian decent type kind of guy with a obese friend with a Asus Tablet. Anyways, they hook the car up try clearing it... Nothing. Goes on a 5+ minute rant of how I'm fked, my car is fked, the A/c system is DEFINTETELY fked and it has no gas. I go into a small sad/angry panic go back to the A/c people, they hook the car up, says pressure is there, all good.

And here I'am not rly wanting to spend more money on this, hoping to draw the good card and all of this being the pressure thing. HELP :D
Click to expand...
I always ask for details when people post about AC issues because inevitably your unfortunate experience is the norm ....................


1. You cannot possibly fill the AC system properly if the pump isn't kicking in - its really simple as that.
2. In order to get the pump to kick in, the pressure switch must be working and indicating an initial pressure of at least the ambient temperature of the amount of R134 refrigerant currently in the system (if the system was empty you need only a very small amount of refrigerant to get you there) - ie around 3Bar as I said on the technicians gauge.
3. Once the pump kicks in you need to keep on filling in order to fill the system properly because the refrigerant is now circulated throughout the whole system - and you keep on filling till the sight glass is full (rough indicator) or the actual measured suction line pressure is around 2.2Bar WITH A RUNNING COMPRESSOR.


Answer this - was the AC not working to begin with? ............ iow why did you take it to the AC guys - working but just not cold enough?
 
L
#14 · (Edited)
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

I totally understand your reaction.


If you dont have the tools or the inclination to do the work yourself, you need to find a professional AC shop - you now have the knowledge to see if they are buggering around and only stealing your money.


........... and to answer the question about the pressure sensor testing - its not sensible/easy to test without a proper test bench to simulate pressures - I would say if, with the AC off, the pressure reading of the refrigerant found via a scanner on the ECU in the car is equal/close to the pressure read on a manual gauge connected to the filling port, the sensor is more than likely working just fine.
 
L
#16 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Dainius Daujotas said:
Would I be able to check with a simple elm327 blueetoth thing? Or would I need a proper connection
Click to expand...
On the Scenic II like yours and mine the pressure sensor is located on the high pressure line running to the condenser (protection checks for overpressure) - for that reason you need to be aware of the R134 pressure vs temp chart in order to make heads or tails of the reading you get there - iow its not a simple reading that always will be the same - eg - at an ambient of 30C you want to measure about 15Bar+ on the pressure parameter WITH THE COMPRESSOR RUNNING and the system near properly charged.



If your ELM327 gets you the refrigerant pressure on your particular ECU then sure you can use that to see whats going on BUT NOT TO PROPERLY FILL THE SYSTEM
 
#19 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Cannot make out what ECU OP has fitted, Just EDC16.. .
so not sure if short to battery is from the pressure sensor , but something back of my mind is saying this is the fault the ECU logs to stop it working if other faults are present
would think AC guys have bypassed this sensor by applying power to the pump, to get the system to work ( Naughty people )..
 
D
#20 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Ok... So I opened the front and Low and Behold the sensor isnt even plugged in... NOTHING AND SAME. Thou, if I had to bet my money it wasnt the ac ppl, it was the ppl who fixed my generator before, since the pressure sensor error was after that repair while the Ac people didnt even touch anything there.

Ours you mention the Ecu not letting it work because other faults are present. I did hear from a different Scenic owner, that once his system leaked and he fixed it, before it started working he had to clear the fault. And now,,, maybe that I plugged the damn sensor in, all I need is a reset...? Also I tried checking the plug with a voltmeter and it kinda gave 0's but Im not sure I was doing it correctly.

Edit: BTW! Is there a easy way to find out my Ecu name? Or what kind of Ecu it is?
 
#21 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Yours Climate Control ..
Would go have the Aircon system checked now multiplug is on, and see what codes will clear..
Themoplungers, though not sure if part of AC or Ecu as regards stopping AC, dont think they are,, would leave alone.
As you can not not buy these separately , ( You have 4 , look like glowplugs )
 
D
#22 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

I tried connecting to the Ecu myself through ddt4all program, and I saw faults from the injection that I have( I get "Check Injection light" time to time) but did not see any error fault codes for Ac. Buuut, I tried disconnecting the sensor and I still didnt really get a error. So either the program was ill suited for Ac checking or there arent any fault codes for Ac. Anyways, guess Ill go down to a electrician tomorrow and see what he tells me.

Also one more thing, I tried checking the Voltage of the plug itself. And it all came back 0, except for when the fan randomly started working, then one of the connections( I imagine the + one?) Was around ~3.5V (And I think it should be 5?) Could that indicate something?
 
D
#24 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Okay fair enough. Means that the electrician is the person to go 2. I guess before that I can try going to a service and ask them to hook up the system and check if the gas is still even there, but I feel like just to be safe I will go to the guy either way(I got a recommendation of a good one who deals with Renaults specifically so hopes are high he will tell me everything). Ill post an update as soon as I know something. And thanks for you input so far!

Edit: Forgot to mention but when I was hooked up to the computer chilling in the Ac settings, the Ecu seemed to react to me pressing the A/c button as it showed something like "Request to Ac" Active or Inactive depending if On or off. But maybe Im misunderstanding something. But that means that the Ecu sends the command to Activate Ac and it gets it? In those same settings I remember seeing the passenger side fan information where it also showed Active or Inactive depending if the blowers were on.

Sorry for the randomly wrote down information, Im just trying to remember the details as best as I can, as that kind of caught my eye.
 
L
#25 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Sorry had to attend to a demanding Cayenne yesterday so missed out on part of the fun.


See you mention DDT ................ have you then managed to get to look at values for the refrigerant pressures now that you have connected the pressure sensor?


I would sort this aspect first imo - make sure you personally know and can monitor what the pressure in the system is.


Its good news that you report seeing the ECU reacting to the pressing of the AC button ................ can you confirm the engine speed bump/sound changes in sympathy with that parameter changing state (ECU compensates for the compressor pump load)?


What is you vehicle's 4 digit model code ?
 
D
#26 · (Edited)
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Hey @LvR

Mmm yeah I did manage to hook DD.. up to the car and look at a few things. But I think I tried searching for the pressure sensor values but didnt see/find them.

And yeah I agree with you that probably now it would be a good idea. But once again I can only monitor the pressure with proper pressure gauges I suppose. Because at least when It comes the Ecu I don't really have a clue where to look. All I remember seeing is was some -40C temp values in there, and thats it,

And no, deffo cannot confirm the rev changes if that's what you asking, doesn't seem to be any. So A-My compressor is fked B-No pressure in the system to begin with C-Maybe just maybe some fault in the Ecu... But at least DD didnt show any faults related to the A/c Thou! I did try unplugging the pressure sensor and seeing if that shows a fault, it didnt. So either the program I was using wasnt that good, or I dunno (All wild guessing by me ofc :D)

Anywho, I should manage to meet a PROPER electrician this time as recommended by many, and he will probably tell me all I have to know. Since I'm also experiencing a "Check Injection" fault rather often, so would like to get that sorted out at the same time as well.

Edit: Scheduled a meeting tomorrow morning. And for now I kind of ran out of options of what I can do. Except for maybe trying to go to a service and ask them to check if there is any pressure in the system, because maybe... just because that sensor was unplugged( I'm still really mad as how this came to be) and the system not properly filled that now the reason it isnt working(or me seeing a fault) is just that there isnt enough pressure in it for it to even work.
 
D
#27 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Some adition. Went to some ac people, they hooked it up, checking the freon and it was at ~350g full is 550g, so either the system has leaked, or the system wasnt filled up properly (If its another leak im gonna evaporate like the gas in the car)

So I filled the system up but ofc it still doesnt work, So fingers still crossed for tomorrow and that the electrician guy will answer all my problems.

Also @LvR I'm not sure what is a 4 digital code you mention.
 
L
#28 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Refrigerant pressure is found in the ECU section - its here that its used to compensate the engine speed, torque output and also battery charge rate .


In order to fill the system yes - unfortunately the gauges hung off the LP port is the only reading to trust. However - the high pressure line's measured pressure (your sensor's purpose) can help you check the guys are not overfilling the system and thereby again screwing you.


If you saw -40C temps on there I guess you have no or very little refrigerant in the system (low pressure refrigerant = low temperature on the P vs T chart) .............. lets hope as you say you now have a situation where a low refrigerant pressure is simply disabling and protecting the pump.
Went to some ac people, they hooked it up, checking the freon and it was at ~350g full is 550g, so either the system has leaked, or the system wasnt filled up properly (If its another leak im gonna evaporate like the gas in the car)

So I filled the system up but ofc it still doesnt work, So fingers still crossed for tomorrow and that the electrician guy will answer all my problems.

Also @LvR I'm not sure what is a 4 digital code you mention.
Click to expand...
So just imo - I don't know anybody that can hang a gauge of the AC system and come up with a statement as to the weight of refrigerant currently in the system ...................:eek::confused:


Also imo only - again - how the heck did they fill the system properly without the pump kicking in ?:crazy:


On your driver's door pillar there is a sticker with your Vin number on it - its the 4 characters found in position 4,5,6, and 7 of the Vin number - mine is eg JM1B - yours will be something similar like JMxx
 
D
#31 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

LvR said:
Refrigerant pressure is found in the ECU section - its here that its used to compensate the engine speed, torque output and also battery charge rate .


In order to fill the system yes - unfortunately the gauges hung off the LP port is the only reading to trust. However - the high pressure line's measured pressure (your sensor's purpose) can help you check the guys are not overfilling the system and thereby again screwing you.


If you saw -40C temps on there I guess you have no or very little refrigerant in the system (low pressure refrigerant = low temperature on the P vs T chart) .............. lets hope as you say you now have a situation where a low refrigerant pressure is simply disabling and protecting the pump.So just imo - I don't know anybody that can hang a gauge of the AC system and come up with a statement as to the weight of refrigerant currently in the system ...................:eek::confused:


Also imo only - again - how the heck did they fill the system properly without the pump kicking in ?:crazy:


On your driver's door pillar there is a sticker with your Vin number on it - its the 4 characters found in position 4,5,6, and 7 of the Vin number - mine is eg JM1B - yours will be something similar like JMxx
Click to expand...
Don't forget my system only has one connection to it (Its the high pressure one?Don't remember :D)Once again sorry if im misunderstanding what you saying :D

Maybe I wasnt clear. They checked the level by pulling out all the refrigerant out of the system which was 350g, then they put it all back in + and extra 200g. Once again yes, this was done with the car turned off, Then when he was done he asked me to turn the car on, he looked at the pressure metter on his machine and said yeah your ?pump? I believe he said wasnt engaging. And thats that, he removed the thing, put some thing on to see if there were no leaks from the gauge on the pipe and thats that.

Ill get the Number thing in a few minutes when i go downstairs
 
D
#34 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

Alright... It works... The problem was 2 things, the sensor and the actual plug... I changed the sensor the day before but it still wasnt working. So he checked all the leads... All the wires seemed to be fine, we were almost ,,giving up,, when he noticed that the holes of the plug seem to be a bit too wide(as in they have been forced, or it was tried to plug in a different sensor???) Anyways, he fiddled about it, made the holes for the contacts in the plug smaller, we hook it up, And baaam we hear a click and it starts blowing cold!!!! After that just 4fun I tried fitting the old sensor back and it didnt work.

MORE QUESTIONS THOUGH!
After we shut the car down, we heard a small hissing sound(as if air was leaking from the system?) for about ~10secs max, Is that just the pressure regulating itself? Or could there be a leak somwhere? I would guess the sound was coming somwhere from the front where the radiator was.
Also the blow isnt that strong(but that is most likely cuz I havent changed the cabin filter in awhile?right?)
The Electrician guy said the same thing as you @LvR, that now it also might be that the amout of gas in is low, because the compressor wasnt kicking in when they topped it up.
So he recommended to go vacuum(I think he said that) check the system or smth like that.
 
L
#35 ·
Re: A/c pressure Sensor Test Renault Scenic II 1.9dci 96kw (131Hp)

OK then - glad you at least seem to be making headway now.


Re the hissing sound:


Once the regulating valve located on the evaporator starts closing to prevent ice forming on the coils, the pressurized refrigerant coming form the pump is stored in the accumulator till its needed or until the pump gets switched off - then, if the accumulator has liquid in it and the pump is off (either AC control system or you switch ignition off), and your expansion control valve on the evaporator in the car opens because its sensing a non-freezing temp on the coils, the liquid will slowly move to the car's interior and you will hear a hiss as the liquid flashes to gas in the evaporator ................ so could be that what you heard is normal.


Re the uncertainty of the refrigerant volume in the system:


That's why I earlier commented "no exceptions" for the filling method - that is the absolute only guaranteed way to properly fill an AC system plumbing. Sure - in the factory the avg production volume of the AC plumbing is very close to fixed so for a std and non-modified AC plumbing one can easily spec an expected volume/weight of refrigerant to use to fill the system, but in your case you have replaced a hose and joints with a new assembly possibly differing in volume from the factory spec .......................... and as such there now is uncertainty about the fill of the system.


Yeah sure - you will have some people argue its probably good enough and if you want to listen to those guys then fine by me too.



If you want it done right though, the AC guys doing refill must use a R134 PT chart, measure ambient temp, follow what I said before and make sure the LP side actually is regulated by the expansion valve and that the HP side runs with about 5 to 10C differential to environment - this will ensure your HP side doesn't cause the pump to get disabled because of over-pressurization and you again start complaining that the AC isn't cold or doesn't work on hot days after all the money and effort spent.


FWIW - imo you never slap a slug of refrigerant (even the assumed correct volume as per spec on the system sticker) onto the LP side of the compressor without the thing running - you can sustain damage on the pump - it simply smacks of unprofessionalism


The blowing aspect you are on your own if you suspect the filter needs replacement already


I reckon you need to be able to view the HP refrigerant pressure yourself on a scanner just to check on the jokers filling the thing



Sorry for the many words - heres hoping somebody else at least get to save a ton of money by getting to know the basics of AC
 
Independent Renault Forums
posts
1.6M
members
226K
Since
2005
RenaultForums.co.uk is the best place to discuss the French automaker’s cars including the Megane, Clio, Modus, Captur and more. Join now!
Full Forum Listing
Explore Our Forums
Engines Electronics Welcome to RenaultForums Cars & motoring Bodywork