VAG AC compressor--Solenoid Control Valve--SNAP RING!!!!

[metanosis]

Got a 2014 Q5 with a Denso AC compressor. Symptoms indicate bad Solenoid Control Valve, its held in place by a snap ring.
Got the snap ring off, replaced the valve, put the snap ring back on. Was not confident it was on, since I couldn't tell for sure it was grabbing into the groove...
spent some time with a screw driver making sure it was seated....tried to pull the valve back out...no way.....my understanding is snap rings are either on or off...it seemed to be on....
but when tried to pressurized the system with refridgerant....it popped off.


Are these a known problem? Is it possible the valve I have is defective, and doesn't quite fit into the snap ring groove?


Don't want to take it back to the fellow who is doing the refrigerant and have this happen again!!!

Thanks in advance.....

[EuroxS4]

No normally you get something like this diagnosed. If you have VCDS you can look at the necessary IDE channels. However Since the system has been opened its kind of too late for that. You shouldn't have any issues getting the n280 and span ring to seat unless perhaps using a aftermarket unit that's the wrong height.

[metanosis]

Thanks for reply.....refitted the snap ring....after using a dremel to clear out some gunk in the groove....it did seat differently, and more securely.....
...though compressor still not coming on....getting 12v at the N280 valve with AC switch on....and replaced the G395.....have an old version of VCDS....am not getting anything
on MVB 54 for G395 readings....so will check that when new unit comes in....but am thinking bad compressor....the AC just quit, from cold to hot in a few seconds...and never came back.....
also checked the old N280....and it appears to work as well.....should have checked this first!

Update.....got updated VCDS.....
[1] Put 16OZ UV dye 134a into system.....6.0Bar.....
[2] Engine on, AC on....no compressor off codes.....N280 getting amps....G395 reading pressure 6.0Bar(no increase with AC on).....No cold air.....
[3] Tried UV light....could not see any leaks......
[4] Listened to compressor....(used wood stick)....sounds like liquid flowing.....but no mechanical sounds...not sure what to listen for.
Thinking bad compressor....2014...with 156K...originally from Texas.....

[Turbo510]

I posted the wrap-up of my son's non-working AC on 6/14. It was the compressor that failed, and after installing the new one plus refrigerant and PAG oil replacement, he's got AC again (in the Phoenix AZ area too).

[metanosis]

Glad that worked.....am about ready to go that route.....what kind of tests did you do? You mentioned there was no resistance when rotating the compressor....
I have read where it should turn freely....mine turns very freely!...maybe there should be some resistance to indicate its actually turning?
Thanks in advance...hope all stays cool!

[Turbo510]

The tests that we did were generally using VCDS; system status, pressure, and control valve current. Those initially looked normal. He had previously gotten the system evacuated and refilled to spec, with no AC action. He changed the pressure sensor at the condenser, with no effect. At first the AC light on the HVAC panel would stay on, later it would not, so pressure was evidently being lost.

The difference in turning the pulley on the old and new compressors was significant. The old one spun like nothing was happening inside. The new one felt like things were moving inside, and made sounds at the open hose ports as air was sucked in and discharged.