Automotive Air Conditioning Information Forum

Sept. 2018 the AC compressor on my 2004 Frontier seized up about 100 miles into our vacation. Oct. 2018 I replaced the compressor, condenser, receiver-drier, flushed the high pressure lines, evacuated and filled with R134 and added some UV dye.

Vent temperatures have been fine. Only concern was that on first use of AC each day (first time I pressed the AC on-off switch each day), there was a metallic grind-type noise the first half-second as the compressor engaged. When cycling, or turning on the AC switch on subsequent trips that day, no noise at all, silent operation. I even tried with engine cold first thing in the morning to turn the ac compressor drive plate by hand, turned readily, and smoothly; then I started up and when I pressed in the AC switch, got the same noise for the half second. Ambient temperature a first start of the day did not seem to affect this at all.

Jump to May 2020. On this Frontier I was still on the factory AC idler pulley at 105K miles, so I bought a new idler for $42 to swap that in (I'd had to replace same part on my 1998 Frontier previously when its idler seized up). So I installed the idler, and the factory one had just a twinkling of vibration when I spun it by hand. Anyway, after that, and with AC belt a little looser, I started it up; and when I pushed in the AC button, the noise appeared again for its usual half-second.

So next day, I decided that I wanted to hear the noise while being under the hood. Since my AC compressor won't engage unless the engine is running (or I jump its wire), I pulled the "AC compressor" fuse just rearward of the battery. I started the engine, turned AC on (switch "in"), and went up to the front. I inserted the AC compressor fuse and the compressor engaged BUT WITHOUT THE NOISE. So I pulled the fuse again and cleaned up its contact arms/blades, even though they looked OK, and re-inserted the fuse.

I fully realize that I'll jinx myself my writing this, but in two subsequent "first AC switch on of the day" situations, the noise has not occurred.

I'm open to any explanations, as to why somewhat-intermittent contact of the fuse blades would cause such a noise,and only on the first start up of the day.

Al9 wrote:The fact you could readily and smoothly turn it by hand means lubrication issues are unlikely.

That's what I felt too.

Al9 wrote:Have you got that rubber ring type of clutch hub peculiar of Denso 10 series compressors perhaps?

I don't have any idea. It's a brand-new (in 2018) UAC CO10607C compressor.

I'll update this thread as I try this on upcoming days to let folks know if the noise is gone or has reappeared and I'll just "live with it". This truck is at my summer place and we haven't really moved here for the hotter months yet, so cannot check every day.

Update: worked fine/quiet again first thing this morning.

I'll be up here more in a couple of weeks, and will update then.

Al9 wrote:Now that i think of it, did you burnish the clutch (it's a matter of engaging and disengaging AC rapidly and repeatedly basically) right after installing the new comp?

Burnishing??? Not intentionally !!! I don't know anything about this burnishing of the clutch, I'm not a professional mechanic. Unless you count my work on old air-cooled VWs in 1971-1975 !!

I know "some things" about auto AC; I would say that I've installed about a dozen compressors in my lifetime on various vehicles - those compressors work hard, and most of the time - in Arizona. I never burnished one before - what does this do?

I believe our high today was 110F. And morning low was 85F.

Al9 wrote:Getting a stronger magnetic field from the coil might have fixed things up enough to remove that initial slippage.

I'm guessing that is what I was observing: before I R&R'd the AC compressor fuse (and cleaned its blades), there were initially less amps delivered and I was getting a half-second of engagement/slipping noise. Thanks !

Thanks - good information !

I think I'm closing the book on this, calling it "fixed".