AC question: 1988 Sentra 3dr noisy

zakezuke · Mar 21st, 2003, 08:50 PM

This is owned by my sister's au pair presently for roughly 1 week now. The prior owner had the AC pump disconnected, claims that it *WORKS* but makes a racket.

I've been able to conferm that the thing makes noice when the engine is off, and the AC pump pully is turned by hand, it rattles as if the pully is not fully attached to the pump. Is there anything the end user may to resolve this condtion, as in, could it just be pully bolts that came loose? Or am I looking at something more complex that involves, well, dismounting the pump.

Myetball · Mar 21st, 2003, 09:03 PM

My experience with that type of noise is the bearings in the compressor are shot. Try hooking it up and turning on the AC. If it sounds like SHOCK and AWE it's time for a new compressor.

Usual cause is letting the system run almost bone dry and continuing to use the AC. This means there are probably leaks in the system.

SuperSentra4203 · Mar 22nd, 2003, 01:32 AM

I think you should just junk the AC, reducing parastitic drag on the motor, and roll the windows down. AC is for 60+ yr old farts. Roll the windows down, and crank the music. God I love summer!!!!

Myetball · Mar 22nd, 2003, 02:33 AM

Oh man, it depends on where you live. I've already run the AC a few times this year. In a couple of months it will be like hell on earth down here...more like hell's steam bath on earth.

Mar 22nd, 2003, 07:38 AM

I wish I could run without A/C. Right here, I run the A/C every single day, 24/7 whenever I drive. Without A/C its like burning in hell...ok..maybe I'm a little exaggerating

SuperSentra4203 · Mar 22nd, 2003, 02:52 PM

Aw hell, you don't need AC when your doing 90!

Location is key. I also can tolerate alot of heat.

zakezuke · Mar 22nd, 2003, 03:48 PM

Junking the AC is an option, but given that the belt isn't even hooked up, I think storing it on the engine is a viable solution, unless there is some drag on the engine i'm not familar with. As in, I don't know if it's worth the time to disconnect the belt in the non-summer months.

I'm not exactly sure how much drag there is when the AC isn't on. I mean, the pump seems to spin rather freely with ease. I'll be looking at the car later today. I'll check to see if it's still charged, and verify my theory about the noise it's generating. By hand the noise seems "external" to the pump, as if just the pully is loose, though i've not looked at it closely enough to verify.

Myetball · Mar 22nd, 2003, 03:53 PM

It could just be the AC clutch, the part that engages to drive the compressor when you turn it on, then disengages when you turn it off to allow pully to spin freely.

zakezuke · Mar 22nd, 2003, 04:15 PM

Would it be possible to replace a AC clutch without dismounting the pump?

Myetball · Mar 22nd, 2003, 05:46 PM

You should be able to, depends on how much clearance you have.

SuperSentra4203 · Mar 22nd, 2003, 05:49 PM

It would probibly be easier to take the pump off.

zakezuke · Mar 22nd, 2003, 09:05 PM

Ok, more to the point, is it possible to replace without loosing your freon?

Myetball · Mar 23rd, 2003, 12:06 AM

It may be possible but it would be a real bitch. You would be better off pulling the compressor.

I checked my service manaul which covers the Hitachi MJS170 and Atsugi NVR140 compressors. I wouldn't want to do it without pulling the compressor.

See if you can tell what model compressor you have.

zakezuke · Mar 23rd, 2003, 12:15 AM

Will do so just as soon as the auto arives here for it's pre-roadtrip tune up, the driver has reschedualed.

zakezuke · Mar 24th, 2003, 04:38 AM

To be honest, I was unable to determine the model of the compressor, and the photographs left with the driver off to cali for 2 weeks. The engine was recently cleaned, but I could find no obvious model number on it.

I was able to put a belt on it and verify the following information

1. AC works just fine
2. AC when on makes NO unusual noise
3. AC makes a rattling noise only when off, as if it's shaking apart
4. I could see no obvious mounting bolts on the main pully.
5. The AC will not be reconnected till this issue is resolved and isn't very important in washington.