hello everyone and yeah, im back again with this loud ticking problem. i followed the advice of everyone from my earlier posts and took off my belt and ran my truck and no noise. i also spun every thing that spins and no noise. when i put the belt back on and start it, theres the ticking again. i thought it was the water pump but no signs of it malfunctioning at all. i swear the ticking is coming from my ac compressor because thats where it is loudest and also i put my hand on every component and i can feel the most vibration on the compressor, in fact, thats where i feel the vibration period. another hint is that when i put my heat on 64 degrees, it feels like 100 degrees but when i put it on 62 degrees the ac kicks in and it gets a little cooler and i do see it spinning but the noise doesnt change at all. my question is are those tell tale signs of a failing compressor?? and is it possible for a compressor to do that and still halfway work? i really think that this is whats throwing me off. one more question, is the oil pump belt driven at all and how does it work?? i was thinking that may be a culprit also but again no noise when the belt is off and no leaks or oil light. thanks for any suggestions guys.

 

did you inspect the inside of the belt? i had a faint ticking noise once and i discovered a small spot on the belt maybe a 1/16 of an inch piece had came off across the width of the belt. got a new belt and the sound was gone.

 

No, if you would look, you would see the oil pump is not belt driven.
Remove the belt and spin each pulley, 1 at a time till you find the noise.

 

And while you can feel the vibration when running by touch, if you use that very same hand to hold a stick (broom handle, long screwdriver, etc.) between your ear and that suspected noise source you will hear it so much better.

Here's a pix of the oil pump, it is inside the front cover, directly behind the big crankshaft pulley on the front. This one is cracked and can make a tick.

 

what year is your truck?

 

An AC clutch can make noise, but normally that noise will change when AC compressor is engaged.

 

oh, ok. the truck is an 03 and out of the death vin range. no noise at all when the belt is off so i thought that would rule out the oil pump. i did put a screwdriver on the compressor and all the other components and the tick is loudest at the compressor. the tick is loud whether the ac is on or off. i did check the belt and its fine. i just dont see what could make a compressor tick that loud. the only clue i have is the extreme heat when the temp is at a low setting (ie) 63-65 degrees.

 

OK, addressing the compressor - if the refrigerant level was critically low the pressure switch would keep the compressor from kicking on. If the level was good and the compressor bad you should have a fault code in the Motronic (can't say if its a standard OBDII or not). The best bet is to check the pressures to either confirm or eliminate a faulty compressor or refrigerant issue. If neither the heating issue may be a faulty blend door servo motor.

You can check for HVAC fault codes by (with the key off) holding down the auto and air distribution buttons and then turning the key to position two. The display will flash a few time and read FC followed by the code number. If it reads 00 then no faults otherwise it will go through the faults and then read 00 to indicate the end of the fault list. RH blend is 32 and LH blend is 31. Codes only show up for an OC or short so the diagnostic capabilities are limited and you could still have a motor issue but no FC.

Agree with the above comment on noise changing when engaged. Generally the noise is isolated to engaged or disengaged. The clutches and bearings on these Denso compressors are sensitive to water ingress so If you wash the engine always take it for a drive to dry everything out.

Make sure the noise isn't coming from the purge valve, they love to tick and the location of the noise can be deceiving.

 

have you tried simply unplugging the compressor, if you do that will only leave the clutch spinning and not the compressor internals.
If you unplug it and the noise goes away you have a bad compressor (maybe a valve plate) if you unplug it and the noise is still there you probablly have a bad clutch assembly.

 

Good point on the low refrigerant making compressor not turn on, so that might explain noise not changing. Need someone to operate buttons while you observe.

The compressor clutch has bearings in it and turns whenever belt is moving, AC on or off. Frequently, if compressor turns on, the increased load will make the sound change, but not always. Rover wants you to change the whole compressor, but the clutch is available I believe thru AC repair shops, on-line, etc. You may have to google the clutch repair for that particular compressor (Denso, etc.). Seems like we have had posts by an owner from Miami with a compressor that he replaced the clutch on. Now if it can be done on the truck, not vent any refrigerant, that would be good. Or you may need to go to an AC indy shop to remove your refrigeraant and recharge after clutch work done. Probably worth a call to a local one.

Of course a whole new compressor and clutch is like $275 on line, less at salvage. Some might be tempted to buy a salvage yard compressor, examine it, and swap out just the clutch. Would be a PITA to relalce all that, and find out compressor dies next summer. Many times a clutch associated with a rotating device is "holding hands while they jump off the cliff together", that is to say the clutch may have failed because compressor is starting to lock up on it.

In the Chevy and Ford world, they make AC compressor bypass barckets, so a truck can have the compressor removed, a bracket with an idler pulley is installed, and the truck goes back to work with same belt but without AC (which makes the driver an unhappy fellow, but at least he is still pulling down a paycheck).