This is strange... Im new to my 03 Discovery 4.6 with 83k and after I purchased it with mild stumble at idle the dealer said was bad coil so replaced it and wires... well its MUCH better but still have a miss... on side of cylinder #2 but only code now once resetting so far shows P1535 which I discussed on another thread here and apparently an a/c issue.. anyway.. I hear the groan and whine only a little in the daytime but at night is is very loud sounds allot like steering pump but I did the hose to ear test and definitely hear it from A/C compressor... A/C works great but I don't think I ever see the clutch disengage... and then of course that code... is this the a/C compressor or something else being at night even here in south florida same temperature, its much louder to point you don't want to drive it at night... not to mention, the added 3 amigos showing up only when turning on headlights and using LEFT signal...

 

Wonder if you AC refrigerant charge is correct, a low charge can make a unit run longer and longer...

Also, the AC fan inside the truck has variable speed, are you sure noise not from there? The sunlight sensors make it change speed from day to night.

If you have two un-related electrical things causing 3 Amigos, you may have damaged wiring, skinned wiring, moisture in connectors or fuse blocks, etc. Something is providing the electrical path....

Time for some serious time with the RAVE.

 

This is definitely coming from compressor and when I'm outside under hood facing engine and tap the theory is sounds like a loud buzzing that changes pitch with rpm... Same sound you get from a low fluid power steering pump whine but I traced it to Ac... I checked freon and it was a little low mYbe never was serviced... ? Might need a likely more? It still blows ice cold as always...

 

look at this drawing from RAVE manual. Looks like you could pull fuse 6 from the underhood fuse box and force compressor off, if clutch works (guess clutch could be stuck).

 

Ok .... Am I just testing to see if clutch disengages ? And if not then clutch locked on?

 

Well it is a test to see if clutch drops out, if it does not, you have other issues. There would also be a plug at the compressor that will drop power to the clutch. I'd whine too if I had to work all the time...

 

hahaha yup.. its a whiner all right and its loud enough I hesitate to drive it...lol so If the compressor clutch doesn't disingauge I guess Ill be needing replace compressor? its loud enough I don't want take truck over 1300rpm... also it seems to drag down idle to around 450rpm... is this symptoms of failing bearings? Im going to slide off the serpentine tonight if I have enough UMF after work 11pm and see if I can spin pulley freely and listen...

 

AC compressor can be siezed or almost, and load down the belt system when clutch is engaged. May can replace clutch separate from compressor, but usually just about as cheap to replace whole thing.

Another thing you can do BEFORE you remove belt it to listen thru a stick to each device the belt passes over. If one is really loud, it would be a suspect.

 

Yes... thats what I did and it was growling and howling and whining... a/c still cold but is just loud.. sounds like when I power steering pump goes how that buzzing sound but defiantly coming from A/C compressor... I added 2 of those cans , one with some PAG oil and it didn't make any difference or quiet anything down on the compressor...

Oh yeah! today when leaving banks.. HA! ... I heard something that sounded like a belt slip and got a quick grinding sound then normal the again... then went back to just that whine sound... maybe the pulley locked for a second??!!

so I guess now I can go have freon evacuated and then I pull a vacuum on the system then remove/ replace compressor or do the vacuum at home after they have evacuated freon?? Im a little confused about that one thing... If I take to shop and have it evacuated and vacuum pulled then can I drive it home, do the work(replace compressor), then take back and let them load er up on freon?

 

Just took off cap covering A/C compressor pulley clutch and noticed the clutch pulley bolt is missing! what size do I need for replacement? maybe that is what is causing the terrible whine! A/C does blow cold and seems to be working .. I was able to manually twist the clutch plate on front with my hand freely... BTW... its a DENSO and Im assuming aftermarket?