Hello all, I haven't driven the car for a couple of months due to travel and on return the AC isn't getting cold. It was regassed last year and was working fine when I left. I've read some posts here and think it isn't getting iced up and must be the compressor? Any tips on how to troubleshoot? Kinda stranded as the car isn't driveable during the day now so any advice really appreciated.

Thanks!

 

Which engine do you have? (The compressors are different)

 

2013 2.5 T5 petrol

 

do you hear/feel the compressor kicking on? Does it blow cold to begin with then gets warm or does it not blow any code?

 

no, only hot air. I don’t think the compressor is kicking in at all.

 

OK so its got nothing to do with icing up etc. If the compressor doesn't kick on - or even tries to, then its something electrical - start by checking the fuse, and the relay. The next possible cause is the freon pressure is low and the low pressure sensor has triggered to protect the compressor. you can try jumpering the sensor (I've used a paper clip between the two leads) to see if the compressor clutch tries to engage. The low pressure sensor is usually found on the AC return line going from the firewall back to the compressor so I'd look on the passenger side inner fender. Only try this for a few seconds - don't run it with the the clip in. If that doesn't do anything then you may want to see if you can get an OBD scan of the ECC - that will require some pro equipment like VIDA DICE. PS the fact that you had the AC recharged last year suggests you may have a small leak that will require a dye test to locate. Could be the evaporator, an O ring, etc. This is again where having a pro with the proper equipment is the right way to go.

 

thanks. This is super super helpful! When you say “passenger side” is this for left hand drive (eg USA) or my right hand drive model?

I’ll look for some videos or whatnot on how to short the relay. And I’ll connect and fire up VIDA DICE. But at the moment no errors showing on the screen at least. Plan is to get it back to a garage but just logistically a bit challenging because the car is so hot it really isn’t drivable during the day (and I’m still under a c19 quarantine order just to add to the fun!) and the nearest person who could check is some distance away so was hoping to check if there are some possibilities I could look at first.

 

lol - right hand side, ie the side near the timing belt cover - unless RHDs reversed the engjne too :-)

 

Got it thanks 😅. That’s why I was a bit thrown by “passenger side” as on my car that’s driver’s side. I was assuming your car was therefore LHD but thought I’d better check. I guess “fender” was all the clue I needed as not a word used over here (I think we would call that a wing?)

thanks again for your help. Didn’t get a chance to troubleshoot the car today but no work tomorrow so will try take a look.

 

Certainly could remove the compressor relay (2/22) and send power directly to the the clutch (using a jumper wire) to see if it works. Or swap with a same part number relay if available. Then work backwards as to why the relay is not being turned on or simply not working. The ECM has final say on when the compressor comes on - and it won't turn the compressor on if it thinks the engine is too hot, thinks it's too cold outside, or pressure is too low or high in the ac system. 7/8 is the ac pressure sensor, 7/16 is the engine temp sensor.

 

thanks for this. I checks the fuse and it tested ok. Not sure I’m ready to short relays as I’ve never tried that before. Pull it out? Would it be obvious which two terminals to short ? Tried to find a YouTube or similar on this but didn’t hit gold yet.

 

VIDA showing an error with the pressure sensor so I’m guessing that’s the culprit. Seems to be located on the left hand side of the condenser of facing the car but doesn’t look too easy to get to 😅. And I guess it would need degassing and regassing before and after replacement.

is there an easy way to confirm this is the issue? It’s not clear to me how to activate this as you mentioned.

 

Let's diagnose this rather than guess, cheaper and less frustrating that way. Vida is reporting the ECM does not like the signal from the pressure switch - not that the switch is bad. First step would be to erase those codes and see if they come back, and if the ac still does not work and the code comes back connect ac gauges to the system to verify what the pressure is in the system. Very rarely have I seen a bad pressure switch on newer cars - and most pressure switches are connected to a fitting with a schrader valve - so no freon is lost when replacing most ac pressure switches.

Did you click on the code and follow what VIDA thinks might be the causes?


And to bypass the compressor relay use your test light to find 12v at terminal 3 (where the relay plugs in, engine running ac on) and find terminal 1 - using an ohmmeter to check that terminal goes to the compressor clutch. Sometimes those terminal positions are written on the relay socket of the relay itself. use a short jumper wire between those terminals to send power to the clutch. Or swap relays with a same part number from somewhere else in the car.

 

Thanks Hoonk. Yes, you are right VIDA is only reporting the pressure is too low. I thought I read online the 2013 model wasn’t a Schraeder valve but I could be wrong there but to your point so far not proven what the issue is.

If I understand correctly the next step is to confirm if the pressure is too low - which would suggest a leak in the system or, if the pressure is ok then that would show the sensor to be faulty?

i don’t have any gauges to measure the pressure. And I can’t see an easy way to access the sensor but will try and source some AC pressure gauges on Monday.

This is what VIDA reported.

 

Yes if it's this part number there is no valve.

And if you jumped the relay to run the compressor for 20 seconds or so - if the return/large pipe does not get cold - the system is empty.

 

Ok I think I got it. So:

1. Remove the relay
2. Test light (or multimeter?) check the outputs to the relay for a 12v feed.

3. Locate the AC clutch. Establish which live goes from the relay to the clutch - in order words use a multimeter and check for continuity.

4. Short piece of wire - short the 12v feed line from step 2 to the line from step 3.

I obviously haven’t done this before so thanks for patience and detailed steps.

 

With the 2/22 relay unplugged (and engine running ac on) - there will be 12v at terminals 2 and 3. There may be little numbers written on the relay socket, the relay itself, or the relay may have a wiring diagram on the case. Jump that power to terminal 1 to send power to the ac clutch. Might be able to determine which is terminal 1 with an ohmmeter. With the key off terminal 1 to ground will be close to 0 ohms as the resistance in the clutch coil is minimal. (key on you will maybe blow the fuse in your ohmmeter if you check ohms on a 12v lead)

 

Seems the advice here was spot on. Regassed the system and found the compressor is now activating and the system is cold. Been monitoring it for a week and it definitely seems “less cold” than it was when regassed. Not scientific but I think there’s a leak.

Any obvious way to confirm ? Bottle of water and fairy liquid and look for bubbles ?

 

Certainly. When a system is properly charged using an ac machine - a leak check is done during the charging process. After the freon is pulled out, a vacuum is pulled on the system and held for 5 minutes or so to see if the vacuum stays in. If it passes the leak test the machine will continue with the charging process. Also Dye visible with an ultraviolet light is installed when the car was manufactured and more can be added during the recharging process. Simply examine all areas and components (that you can get to) with an ultraviolet light for dye stains/marks. For a pressurized system a leak detector sniffer is available that sniffs the air near it's probe and will beep - in the presence of freon. Only a small portion of the evaporator (the cold radiator in the car) can be seen or gotten to easily - if there is a large enough leak there the freon will get trapped in the ac box - sometimes putting the sniffer in a vent then turning the fan on you can find a leak.

 

Ok thanks again. Sounds like a job for the professionals. The refill was done with what looks like a simple two connector rig (blue and red) and a small bottle of 134a refrigerant. They wanted to keep the car but unfortunately as I use it for commuting that wasn’t an option and without AC (albeit temporary in this case) the car is simply undriveable. Sounds like identifying the leak is a quick job with the right equipment but probably take some time to resolve depending on where it’s leaking.