AC system noise after 50k maintenance — nervous to take trip

Just did some routine maintenance as well as some preventative maintenance in preparation for a move from VA to NE (diff fluid change, radiator flush, etc.). Now, after the engine has warmed up, there is an odd sound coming from the front of the engine bay. It sounds exactly like an exhaust leak except when I turn off the AC system the sound disappears which kind of baffled me. I was thinking maybe something with the compressor clutch which worries me when I'm leaving on a 1300 mile trip next week.

On the short term why don't you disconnect the pressure switch that connects right as the line comes out of the a/c compressor. this will allow you to run all the vent settings without the a/c engaging at all.

check the electric cooling fan and the fan shroud as well-- when the AC is on, the electric fan runs and can vibrate things that don't make noise otherwise.

P.S. we'll miss you-- but where are you headed in N.E? 1300 is a bit high unless it's round trip.

Shorty said:

check the electric cooling fan and the fan shroud as well-- when the AC is on, the electric fan runs and can vibrate things that don't make noise otherwise.

P.S. we'll miss you-- but where are you headed in N.E? 1300 is a bit high unless it's round trip.

Click to expand...

The electric fan has yet to turn on since the coolant flush. Drove it around with the AC on and it has yet to break 190-200. But yea, I thought the E-fan came on no matter what if the AC was running.

I was thinking maybe the compressor bearing but I don't think the sound matches up.

And Sidney, Nebraska — not the other NE

You can determine the source of the noise with 3' of vinyl tubing, 1/2" ID or less, available at most parts stores and nearly every hardware store. Stick one end of the tubing in your ear, then carefully move the other end around the engine compartment near the various components--you WILL be able to isolate the source. Please watch your hands/clothing--wouldn't want any nasty accidents.

Good luck.

That is a great trick to mention, Joe. My dad taught me that one when I was a kid, it works every time. Also worth noting if you stick a piece of solid rod in the end of it you've got yourself a poor-mans stethescope to hear what is going on internally as well

GrimmJeeper said:

That is a great trick to mention, Joe. My dad taught me that one when I was a kid, it works every time. Also worth noting if you stick a piece of solid rod in the end of it you've got yourself a poor-mans stethescope to hear what is going on internally as well

Click to expand...

Sure thing--my Dad started me out with a hunk of conduit with a short piece of rubber hose on one end. I always use the vinyl tube first, then if I need to isolate more switch over to the mech stethoscope to pinpoint. I know everyone didn't have a great dad, and at times I didn't appreciate mine (I was a fool!), but I sure miss him!

joe_peters said:

I know everyone didn't have a great dad, and at times I didn't appreciate mine (I was a fool!), but I sure miss him!

Click to expand...

my dad was a real bastard, but he knew a thing or two. My only regret is that I was unable to learn more from him than I did. Old guys always know the best tricks.