OK I give up searching past posts, Have AC/Stalling question

[Millersho]

Wow, about 2 years ago I was a regular SHOTIMES viewer, how things have changed, including the popular board.

I have a 90 w/136K and just about every part replaced and a few of the important mods.

The biggest issue I'm having with it is when the AC is engaged, the car will fight to say running.
900-1000K down to 400 then back up to 900 and so on.

It's a given that the AC compressor is bringing this engine to it's knee's at idle.

So what do I need to do to fix it?

THanks in advance fellows

<small>[ September 09, 2002, 04:51 PM: Message edited by: Millersho ]</small>

 

[projectSHO89]

Try cleaning or replacing the IAB.

The, perform the idle program relearn procedure frquently posted by sdpatt.

Welcome back!

Steve
89

 

[Millersho]

So you think this has nothing to do with the AC?

 

[Millersho]

Anyone else want to bite?

 

[Yamaha V6]

Is the compressor binding? If it's a source of resistance due to a mechanical problem, that may be a problem. Seriously though, if you have the ac on while the car is relearning the idle program, it'll see that it needs to bump up the idle a smudge to compensate.

Obviously, if you have a mechanical problem with the AC compressor / clutch, you should consider fixing that rather than band-aiding it.

 

[projectSHO89]

The AC does place a load on the engine.

It is up to the IAB, under the control of the EEC, to compensate for it.

Steve

 

[TimboSHO]

Hey, this is just a little off subject, but my A/C worked when i purchased my 89 a month ago, but now it doesn't. It smells like maybe the compressor isn't running (you know the smell, right?) Is there any way to test the compressor if it's working? Thanks!

 

[projectSHO89]

First, see if the clutch appears to be engaging. If it does, then use an inspection mirror to see if the compressor shaft is actually turning.

My clutch failed so that it appeared to be energizing and turning, but the compressor's internals weren't moving.

What smell are you referring too?

Steve
89

 

[SHOMEUP]

The smell is the rubber burning..

I just replaced my a/c clutch and coil- my problem was that the clutch would engage but the internal compressor wasnt turning due to the rubber being so worn out that it just slipped- the magnetic clutch is attached to the inner circle that spins the compressor(when engage) how this attaches is by rubber and once the rubber gets weak all it does is slip and doesnt turn the compressor- so basically make sure the compressor turns freely and all you need is a new clutch and coil(replace the whole clutch and coil since your down there)

My problem now i also have the weird idle problem- but mine does somethings differently- sometimes when my car is on and i hit the ac to go on- my idle goes up to 2k- than jumps down for a sec than goes back up to 2k and does this until u turn the ac off- but if you turn the car off and back on and than turn ac back on your ok- so its probably my iab and relearning the new idle since i had my battery off for a long time the other day- i just put in a new alt and A/C clutch and the ac works great but sometimes the idle goes weird- hope this helps alittle

Mike

 

[rangerj]

MillerSHO, and others,

If the A/C is putting a "drag" on the engine, more than it normally does, the following may be the cause(s);

1) The A/C pulley bearing may be dry and binding. This would drag with the A/C on or off. The pulley should spin freely, and quietly, when the A/C clutch is not engaged. In the early years the bearing can be replaced. In ther later years the bearing is not available as a replacement part. The KAYO bearing is an odd size, so that "standard" bearings will not work. If your bearing number is the same as the 89, 90, or 91, you can replace your bearing.

2) It should take 7 foot pounds (84 inch pounds) of torque, or less, to turn the A/C compressor shaft. If it takes much more than that,the compressor is dry (lack of oil), the bearings in the compressor are bad, or there is hydrolic pressure in the compressor cylinders due to too much oil, or too much refrigerant, or the refrigerant is bypassing the oriface too quickly, and returning to the compressor as a liquid.

This can happen when the "O" rings in the oriface no longer seal, or have become dislodged. High pressure readings on the low pressure side (an excess over 60 psi), in conjunction with low pressure readings on the high pressure side, indicate a failed oriface. However, it could also indicate a failed compressor!

The rubber connector in the clutch face cushins(dampens)the clutch when it is engaged. The failure of the rubber is usually due to a compressor that is dragging, and a clutch/coil that is working properly, i.e. the coil draws in the clutch, but the compressor does not want to turn. The computer may be trying to compensate for the drop in RPMs, thus your fluctuating idle RPMs.

Replacing the clutch coil, face, and pulley, generally can only be done as a unit. You may be fixing the symptom, and not the problem. Take pressure readings on your A/C system, and do some further diagnostics. Hope this helps, rangerj

 

[93MTXSHO]

How tight is your belt? Just asking because my 93 had a very similar condition. My belt would also squeal, so I just tightened it up. But the car kept doing it. In the end, I found out that it was just that the Compressor was so tight that the engine just couldn't turn it properly at idle. After replacing the compressor/accumulator/lines, everything is fine and works really well.

 

[DHMag]

93MTXSHO:
How tight is your belt? Just asking because my 93 had a very similar condition. My belt would also squeal, so I just tightened it up. But the car kept doing it. In the end, I found out that it was just that the Compressor was so tight that the engine just couldn't turn it properly at idle. After replacing the compressor/accumulator/lines, everything is fine and works really well.

specs quote the belt tensioner pulley to be torqued at around 250 ft lbs. common rule of thumb on ANY belt is tight enough that, between the longest pulley span, you should *just* be able to turn the belt 90 degrees.

 

[shojuan]

DHMag:
specs quote the belt tensioner pulley to be torqued at around 250 ft lbs. common rule of thumb on ANY belt is tight enough that, between the longest pulley span, you should *just* be able to turn the belt 90 degrees.

I think you mean the belt tension is 250 lbs. Big difference from a pulley torqued to 250 ft-lbs. Tension is a function of force only.

BTW, I've wondered on occasion, does *anybody* here have a belt tension gauge? These things are expensive and there are a couple different designs specified by different auto makers. I doubt that even many dealer service departments spring for one. I sure wouldn't mind having one, if it was free hehe.

Rick