72chevy

My 2000 Altima makes a strange sound and it's getting progressively worse.
With the AC on, at highway speeds, I can hear a loud SSsstt every few minuets. It seems to do it when the ambient air temps are higher. The sound started last summer and was really short but it has been getting longer and more frequent.
I took it to a service tech last summer and he said it had the proper amount of freon.
It cools good but when it makes the SSssst sound the blower seems to put out a puff of humid air. (I usually keep it on recirculate in the summer.)

Are there any tests I can do without a set of gauges?

Is there some kind of pressure switch going bad. I hope it's not the compressor.

Thanks in advance.

 

smj999smj

Check your drive belt tension, first, and adjust if necessary. That said, I have a feeling the noise you are hearing is the AC clutch cycing "on" and "off." With the A/C operating, look down at the A/C clutch while someone keeps the engine running at 2500-3000RPM and see if the noise occures in sync with the A/C clutch cycling "on" and "off."

72chevy

I replaced the belts a while back and it did it with the old set and new set. I was able to hear the noise with the hood up and it is happening when the AC clutch is engaging. It looks like there are clutch parts available but the old compressor might give out next anyway.

Brianz01Altima

I have always heard that sound you describe in my 01. My A/c worked great until 160k when the clutch went out. The hiss will occur for a few moments after the clutch has engaged.

If you have high miles the clutch may be going out (the electromagnetic part). The bad news is you will have to replace the whole compressor, as no seperate clutch is available.

smj999smj

Clutch is available......Nissan P/N: 92665-0Z001
That said, you can get a Four Seasons reman. compressor w/ clutch for about $120 cheaper than the cost of the Nissan clutch, alone.

 

Brianz01Altima

I see your point the clutch runs $252 and a whole new compressor assembly runs $338.(Discounted Nissan Parts)

You know, just a few months ago when I replaced my compressor I checked many online nissan part places and they all listed the cluch as "not available", and now everyone has them........

txn

I've been having the Sssst noise for a while now, too. More recently though, my compressor doesn't come on reliably when the outside temp gets into the mid 80's. Is that the clutch or compressor or belt?

Kraut-n-Rice

AC systems will sometimes quick cycle if there is a clogged or faulty expansion valve or switch . I haven't paid that much attention to the AC system operation on this car ,but heres some basics . If the system does have a partial clog the system triple pressure switches see the high pressure build as the compressor runs and shuts off the ac clutch prematurely and doesn't cool efficiently. The liquid tank (accumilator) may be partially clogged also . A certified AC shop or good dealership guy should be able to tell you what the issue is. Sometimes these syptoms come from a compressor going bad and metal debris getting distributed thoughout the AC system. The low side will have extra low pressure when looking at a gauge set and the high side will register high enough to possibly look somewhat normal because excess pressure is blown off from a relief valve on Nissan systems .