tranny / AC compressor help

2000 grand prix gtp 3.8 sup 116k miles

recently noticiing that the car does not want to shift into overdrive as quickly as it should. i only drive it bout 15 miles mostly highway to work each day and lately been noticing that it wants to stay up above the 2k rpm range doing around 60 which is not normal, eventually it will drop down into od.
lets see the filter/tranny fluid has been changed twice in the cars life once at 50k and again at 80k both times with mobil 1 atf and new filter. car has gm tranny cooler for last 5 yrs and i honestly can say i havent beat on it too much over time... all the other gears shift smooth rpms rise right up great will jump into passing gear no problems just getting it to drop into the high gear.
Any help is great other than saying to get a rebuild....

Other question is my ac compressor clutch is starting squeel intermittently when the ac is off, being the middle of winter in the northeast i dont need it much so rather than replace it im thinking of bypassing it.does anyone know what size belt or belt model number i can buy to bypass the ac compressor and if i can even do this on this engine.
thanks

I hate to break the bad news to you but it sounds like the 4th clutch shaft is starting to go so a rebuild may be in order. Common problem with the 4T65E and 4T65E-HD autotransaxles where the splines on the shaft strip or wear out which equates to no 4th - OD or intermittent 4th - OD. When it gets worse the gearing will default to neutral.

There is no belt substitution bypass for the A/C compressor but a bypass kit is available where a dummy pulley and bracket is used after the compressor is removed. Let me know if you need a link to a supplier.

bnaylor, I hat to disagree with you on the tranny issue, but when its colder outside, the PCM doesnt command overdrive untill all the parameters have been met. Some of which include tranny fluid temp and also engine coolant temp. So if the car is cold started when the temp outside is freezing or below, the car wont go into overdrive untill the tranny and coolant temp reaches a certain degrees. So I believe his issue ie percectly normal.

What he can do is to get the car to operating temp and to shift into overdrive. Then come to a complete stop and accellerate up to 55 and see if overdrive locks in as it should.

I agree Tblake on the parameters for 4th - OD but based on the OP's specific reply you'd have to assume he has reached proper operating temperature for 4th - OD to engage to include the TCC lock function on top of that so my reply was based on the OP having a bonifide 4th - OD issue. You are assuming proper operating temp was not reached....correct? I find it hard to believe he has not reached proper operating temperature and TFT parameters have not been met in 15 miles to work for 4th - OD not to engage? His taching at 2K rpms at 60 mph is consistent with being stuck in third gear and 4th not engaging. Maybe the OP can clarify.

BTW - After reaching proper warmup he should see 4th - OD kick in at around 45-47 mph. The tach should show a significant drop in rpms and at 60 mph show around 1500-1700 rpms which includes TCC lockup.

Yes, The impression I got was that it not shifting into OD as quickly as it usually does upon being initially started. The temperature here is rought 15-20 degrees and I know my car wont go into overdrive for probably about 5 miles of driving. If his isnt in by then, then yes I would say there is a problem indeed.

lets see the filter/tranny fluid has been changed twice in the cars life once at 50k and again at 80k both times with mobil 1 atf and new filter.

After reviewing the first post I noticed the above. I'm assuming that is Mobil 1 synthetic ATF? I've heard of interesting issues using synthetic ATF instead of the regular Dextron-III in a 4T65E autotransaxle.

Another option is to run a scan with a trans capable scan tool that will read GM extended DTCs (P1XXX) and see if any tranny related DTCs are stored. I noticed in my ATSG SM many slippage or shift timing codes do not trigger a SES/CEL light but should store for retrieval.

The temperature here is rought 15-20 degrees and I know my car wont go into overdrive for probably about 5 miles of driving. If his isnt in by then, then yes I would say there is a problem indeed.

tblake,

To test your theory it finally got below the freezing mark this morning here in my neck of the woods. I tested my GTP and Regal GS. Temperature was 28 degrees, humidity 37%, chill factor 21 degrees. I gave each one minute warmup time and proceeded immediately to a main road where the speed limit is 55 mph which is one block from my house. Proceeded down the road in normal OD setting (automatic mode) and gradually accelerating - 1/8 throttle or less and progressively/slowly worked up to 55 mph. I observed each shift to each gear and watched the tach at the same time. Distance approximately 1/4 mile give or take. I had no problems getting into 4th - OD in either car. Tach was well below 2K rpms at around 1600 rpms after it settled out. I even saw the TCC lockup after it went into 4th.

yeah, sounds good for 28, I havnt seel a 28 degree day since november. Today topped a whopping 2 degrees with a negative 20 windchill. Maybe he lives near me.