1998 Limited AC Intermittent Clacking (1 Viewer)

[Learning Outdoors]

Ol' Crusty started making a clunking noise from the AC compressor, sometimes it's a very light tapping noise that then fades away. Sometimes sounds like a jackhammer. Sometimes when the AC is engaged. Sometimes with just the fan. Noise persists usually for no more than maybe 3-4 minutes then it's gone.

No squealing, no grinding, no vibrations. AC is super cold. AC compressor clutch is engages and disengages silently. Noise is unpredictable and can disappear for days. And yes, the noise is from the AC compressor or thereabouts. Engine is fine but you'd think it was Son of Rod Knock lurking in there. On my Taco, years ago the tension plate presented with a ticking but that was a continuous noise once the engine warmed up. This is on the opposite end of the engine and specific to the AC compressor area.

The noise is not continuous and it's independent of ambient temp. Any ideas?

Looked online and some say pulley bearings, some say worn idler pulley, some say compressor is dry due to no oil, but nothing definitive.

 

[Learning Outdoors]

Compressor was failing. Replacement of the entire unit and the evaporator canister during the full replacement took care of things. Evaporator canister, as noted on other threads is a default replacement item because if the failing compressor released any kind of abrasive particle (metal or non-metallic), those little pieces can end up hiding in the system, contaminating things, and causing an early failure of your new compressor. Purging the system which is part of the required process does not eliminate the possibility that contaminants remain in the system and the canister is the single most likely place that a purge will not fully remove things. All is well with the AC.

 

[vipergrhd]

Compressor was failing. Replacement of the entire unit and the evaporator canister during the full replacement took care of things. Evaporator canister, as noted on other threads is a default replacement item because if the failing compressor released any kind of abrasive particle (metal or non-metallic), those little pieces can end up hiding in the system, contaminating things, and causing an early failure of your new compressor. Purging the system which is part of the required process does not eliminate the possibility that contaminants remain in the system and the canister is the single most likely place that a purge will not fully remove things. All is well with the AC.

So you have replaced the compressor and the Drier? Did you backflush the condenser?

 

[Learning Outdoors]

Replaced the entire AC compressor unit, replaced the drier, backflushed and tested the entire system by the book. Step by step. Some years ago, the OEM compressor went out on my 2002 Tacoma at 130K miles. Skipped the drier replacement and 30K miles later had to do the job over again so I said never again even if it's a bit more. This 3rd Gen 4Runner had the OEM compressor from 1998 with 285K miles! However, at around 230K miles, the previous owner hit a deer and during that repair, radiator/heat exchanger/AC lines/Drier and all the lines were replaced with new. So, even if the non-compressor parts were not that old (~50K miles), canister type stuff is worth replacing because it's a dead-end component that's difficult to clean out.