Ac Compressor Issue. Anyone Else Experience This?

[ED.]

I've noticed that when it's warm out the AC compressor seems to make its presence known. The fact is even more apparent when it's down right hot outside.

On a normal warm day, the cars feel and idle while tend to "drop" when the AUTO button is pushed and the compressor is engaged. On days when the mercury is the upper 90s, the feel is even more amplified. One Tuesday, I started the car after leaving the gym and I had about two seconds of pretty profound idle flucuation.

Is the compressor that noticeable on these cars? Could I be low on freon? There have even bee instances where I've gone from cool air to rather warm, humid air.

Thanks for the help,

Ed

[steve2006]

Normal warm engine idle speed is around 650rpm when I turn on the AC the idle goes up to around 800rpm. I would assume there is some communication from one ECU to another to get the rpm to increase when the AC is on but how I don't know.

If your AC has not been serviced for some time it wouldn't hurt to have it checked out and topped up if required before going any further.

[ED.]

Mine seems weather related for sure. I never noticed such a drag on the engine like this one on my car.

You're right, I should have it serviced. Just any AC place?

[1990LS400]

Ed, my 2000 LS400 is essentially the same ans yours and changes in it's engine idle speed are not noticeable when the A/C is on either in manual or AUTO mode. Maybe the idle speed is increasing but I don't notice it. It's been pretty hot recently in your area so you should have noticed if your A/C isn't producing enough cold area.

[ED.]

Yeah I've definitely noticed some flucuation in temperature. You can always tell when the AC is not on and the air is very humid.

This pump makes you feel it activate so something is up. The cabin filter was awful but that didn't really have anything to do with it. I don't really trust Jiffy Lube et al, for work so I am not sure where I will take it. I can do a google I guess and see what comes up. There's a place right down from my office I could drop it off at. Greasy spoon theme but they seem pretty nice.

[1990LS400]

Assuming that you are avoiding the dealer, are there no independent Lexus repair shops in your area? Where do your Lexus owning friends take their cars?

[ED.]

The dealer LOL. My buddies car(s) are under CPO warranty. I normally do any maintenance myself (oil change, tune up, suspension items, etc) but for this I will need a pro!

I use to take my car to the "family mechanic" out in Saint Charles (county west of St Louis) but he use to get upset when I would provide my own parts.

Maybe I can take it there and have him look it over or give him a call and see if we diagnose it over the phone.

I need to do something soon since I want to get the windows tinted and I <i>know</i> if I do that first it will be jinxed and who knows what'll happen! Today is beautiful and I am about to go to the driving range but it's going to warm up this week. Which I like....but my car doesn't!

[Robert Young]

Hopefully, the suggestions for A/C fluid level check will fix your problem. However, one thing most of the dealers and mechanics don't seem to be aware of (or don't want to be) is that A/C compressor clutch wear is much more significant with recent cars. The main thing to look for is normal A/C operation when the engine is cold, but the compressor operation starts to cut out when underhood temperature warms up (potentially the cause of the idle issue, as the electronics would get confused). This is due to the shift in design from a compressor that runs 100% of the time with the A/C on to a sytem that cycles the compressor (done for fuel econ), it is the frequent cycling that just wears out the A/C coompressor clutches.

My wife had a Ford Taurus that about drove me crazy with this problem (I know, but she had the Taurus before I knew her). The Ford OEM Nippon Denso compressor clutch would only last about 30k miles or just enough to be outside the Ford warranty, before the wear increased the air gap enough that the clutch coil would not pull it in when warmed up. On her Taurus with the 3.8, changing anything on the engine was a real nightmare! After getting the compressor / clutch replaced once for about $800, I decided to look into what was happening and that was when I found the air gap problem. You should be able to find the air gap spec in the service manuals, but anything much above zero will work. From some place like Snap-On you should be able to buy a tool to remove the compressor clutch plate, fortunately it is on the front and frequently not too difficult to remove with everything in the car and without draining the A/C fluid. On every system I've seen, you can then simply replace the shim washer with one a bit thinner. IN some cases, the dealers will actually have a variety of shims factory OEM. On the Taurus I had to do this about every 20k miles and you could see the wear on the clutch plate when it is removed. The 97 Volvo S90 that she has now has a better specified system, but it still had the same problem at 110k, fix was again easy.

[curiousB]

I doubt many tech follow this procedure (from Lexus HVAC course). You'd have to drain refrigerant... and pull the compressor. If going to this trouble I think most would recommend to replace entire compressor assembly.

When replacing a compressor clutch, place the compressor and

magnetic clutch in a vise. After disassembling the clutch, save the

magnetic clutch shims (washers) to use with the new clutch.

Because the shims are for adjusting clearance, they may vary in

thickness, and there is no specific number of shims used.

After assembling the new clutch with the old shims, set up a dial

indicator to measure clutch hub movement when it is energized.

Connect the battery positive lead to terminal 1 of the magnetic clutch

connector, and the negative lead to the ground wire. Turn the

magnetic clutch on and off to measure the clearance.

If the measured clearance is not within the range specified in the

Repair Manual, remove the magnetic clutch hub and change, add, or

remove shims as necessary.

Before reinstalling the compressor and clutch, be sure to adjust the

oil level in the compressor as described in the Repair Manual.

[jaswood]

I've noticed that when it's warm out the AC compressor seems to make its presence known. The fact is even more apparent when it's down right hot outside.

On a normal warm day, the cars feel and idle while tend to "drop" when the AUTO button is pushed and the compressor is engaged. On days when the mercury is the upper 90s, the feel is even more amplified. One Tuesday, I started the car after leaving the gym and I had about two seconds of pretty profound idle flucuation.

Is the compressor that noticeable on these cars? Could I be low on freon? There have even bee instances where I've gone from cool air to rather warm, humid air.

Thanks for the help,

Ed

Hot and humid engine intake air....

Check the engine air filter and the MAF/IAT (Mass AirFlow sensor and Intake Air Temperature) module.

Disconnect/pause/reconnect the battery on a hot and humid day and let the ECU "relearn" intake conditions in that situation.