Ac clutch on all the time with A/C

[Steveinfl]

Hey everyone,

Everyone here has been very helpful in the past. I may simply need a new a/c compressor, hopefully not as they are costly.

A little background.

Well maintained 03 I-6 with almost 100k miles.

The fan clutch was replaced in 2005 I believe, fairly certain I'm still on the oem water pump.

The car regulates its temperature as well as it always has. Running right around 205-210 in city traffic as the scan tool reports.

Fan clutch operates normally when the a/c is not engaged.

Ac outlet temperature is only carrying about a 20 degree differential, used to be close to double that.

Ac compressor has a rattling sound ( bad description), this is a recent change.

Low side Ac pressure is ~45 psi @ 90 degrees outside and humid.

It had been on my long term list to refresh the water pump, thermostat and fan clutch at some point but I really don't think any of them are malfunctioning. I have been using the a/c as sparingly as possible as I'm scared of the compressor grenading and stranding me somewhere. I should probably purchase an extra serpentine belt to take the compressor out of the loop as I've seen discussed here before but I'm just not sure what the root cause is.

Could a sensor be reporting incorrect pressures in my refrigerant?

Should a compressor last past 100k miles?

This is a side note but I saw that there is a group order for club tshirts taking place. I sent a pm to the op which started the tshirt thread but haven't heard back. I don't want to miss out on the group buy.

Thanks for any advice you all have to offer?

 

[DJones]

Ac compressor has a rattling sound (bad description), this is a recent change.

Should a compressor last past 100k miles?

The rattling sound is how I figured out what part on my A/C compressor was bad. It ended up being the bearings inside the pulley. It was easily noticeable after I removed the belt and played 'spin the pulley'.

As far as I know, I am on the original compressor at 201K but the refrigerant did need to get replaced once when a car accident left a hole in my condenser. If you need a compressor, let me know I have one available but it doesn't have the pulley or clutch plate.

 

[djthumper]

That is how I found that the bearings were bad in my clutch. It can be a pain but I think yours just needs the clutch rebuilt.

 

[Steveinfl]

I definitely prefer that to a brand new unit. I remember seeing a thread showing how to replace those parts. Is that something I could have a mechanic do or am I on my own.

Did your Ac function normally and just rattle or was it malfunctioning at the same time?

 

[djthumper]

I definitely prefer that to a brand new unit. I remember seeing a thread showing how to replace those parts. Is that something I could have a mechanic do or am I on my own.

Did your Ac function normally and just rattle or was it malfunctioning at the same time?

It functioned normal but the rattle was loud.. A mechanic should be able to handle it.

 

[Steveinfl]

10-4. I will look over that thread but I am pretty sure there is a correlation between the Ac being turned on and that fan clutch being turned on on continuously. Not sure what it is yet, but it functions normally with Ac off but is constant with ac on.

 

[djthumper]

10-4. I will look over that thread but I am pretty sure there is a correlation between the Ac being turned on and that fan clutch being turned on on continuously. Not sure what it is yet, but it functions normally with Ac off but is constant with ac on.

It is the friction that will cause it to stay running. If the bearing seizes it can keep the clutch engaged and the rattling is when it frees up. IIRC When I was taking mine apart the bearing pack came apart.

 

[Steveinfl]

Oh. I just connected the dots. I had myself confused over this. So the Ac clutch seizes which causes the computer to continuously command the fan clutch to stay on. Gotya. I had a brain fart there.

 

[DJones]

Is that something I could have a mechanic do or am I on my own.

Did your Ac function normally and just rattle or was it malfunctioning at the same time?

It depends on where your problem actually is. For mine, the clutch had a strong enough magnetic field to hold a crow bar to it, but the clutch plate could never touch the pulley. The A/C was "on" but only warm air would come out because the compressor shaft wasn't turning.

When I was taking mine apart the bearing pack came apart.

You had it worse than I did.

Oh. I just connected the dots. I had myself confused over this. So the Ac clutch seizes which causes the computer to continuously command the fan clutch to stay on. Gotya. I had a brain fart there.

You can do another test by removing the clutch plate. Easy to do, one bolt with something to prevent anything from moving.

 

[meerschm]

I have 150k on mine and recently replaced the ac compressor clutch. (but i do not live in florida)

you really need to measure low side and high side pressure to see if things are working ok. (or have someone do it)

I would not delay figuring what is going on.

the fan clutch is commanded by the computer, not by the ac clutch. needing ac does influence fan operation.

does your ac clutch cycle on and off? could be lots of things, including a clogged up condenser or evaporator coils.

you are sure it is the ac clutch making the racket? is it the same whether AC set or not? (not the idler pulley?)

your title threw me off a bit. thought you were saying the ac clutch was always engaged.

 

[Steveinfl]

I need to pull the belt and test each pulley for noise, but the Ac isn't functioning as well as it should. I don't doubt that I need to replace the Ac clutch bearings, that is on the short list. There is absolutely a correlation somehow between having my Ac engaged and the radiator fan clutch permanently engaging. The radiator fan clutch does not behave this way when the Ac is off. I need to have an Ac shop look at it first and see where that goes.

Would an Ac clutch that isn't engaging and disengaging as it should cause a pressure abnormality in the system causing the computer to engage the radiator fan clutch?

 

[meerschm]

The computer tells the fan clutch to engage, and how much.

the computer knows you have the A/C on, and considers this information, with other sensors, when it processes where the fan clutch needs to be set. when the ac is on, in most cases, the fan needs to engage. there are several temperature sensors in the system, as well as high side pressure sensors.



If the compressor clutch is not disengaging, the pressure in the system can get too high, and break something. if the compressor clutch does not engage when it should, the compressor does not operate.

in normal operation, the compressor clutch cycles on and off ( in some cases stays on for quite a while, for high heat loads in warm weather)

typical problem is when some R134a leaks out, and the compressor works, but the low pressure switch detects low side getting too low, and turning off the compressor. this cycling is normal when it is cool, but when it is hot, and you need full ac, the system would run all the time. if there is not enough R134a in the system, the low pressure switch works too much, (doing it's job of preventing a vacuum being pulled) resulting in too little cooling, since the compressor is turned off much of the time.

for a ten year old system, it would not be out of the question that some has seeped out. after checking high side and low side pressure, if this indicates low R134a, best plan is to find the leak and fix it (perhaps by filling R134a with a leak detect florescent dye, and using the dye to find the leak), then have a place pull a vacuum, then fill with the right amount of R134a.

if your compressor is shot, it needs to be replaced. if you think the compressor is fine, except for the clutch or clutch bearing, you can go with them. for the most part, a mechanic will want to replace the compressor, since it is a bit of a pain to replace the clutch/bearing while on the car, and once you have the compressor off the car, it is better to replace with a new or rebuilt unit, and probably change dryer, than to change a part which may or may not be the problem. the a/c compressor is not right on top where it is easy to change the clutch/bearing.

I would get the ac working, and then look to see how the fan behaves.

you still have not told us if your AC compressor clutch is staying engaged, or cycling on and off (with the ac on full blast and windows open) should be easy to see. be careful of the moving belts/fans.

also, does the accumulator/dryer get cold to the touch? should be cold and wet (like an ice cold can of beer on a hot, sticky day)
http://www.rockauto.com/catalog/moreinfo.php?pk=3913140&cc=1398719

have you looked at the condenser to see if it is full of dirt/bugs?

 

[Steveinfl]

The Ac clutch only engages and disengages with the in cabin switch, it does not cycle while the Ac is on as it should.

The junction where you would top off refrigerant ( the accumulater?) is cold as well as the metal tube running horizontally across the front of the motor, however the condenser is moderately warm.

The condenser is relatively clean, certainly not dirty enough to block airflow, I have no other cooling issues ( radiator) so I don't believe it is airflow related.

It's still
The case that my radiator fan clutch is on 100% if the time that my Ac is on, and it cycles normally when the Ac is off.

 

[meerschm]

when the ac is on, it does not always cycle; under some conditions, it just stays engaged. (when it is warm and humid, and has enough R134a)

it should cut off if the ac is on, but temperature inside the cabin is cool enough. (if you have the ac on, verify the AC clutch is engaged, and increase the temp control, it should cut off when it figures out the cabin is cool enough)

 

[Steveinfl]

I got in and drove around till I had the car at 70 degrees. I waited for the fans to wind down as I just use the auto temp setting. The recirculate function was off, I believe that always runs the Ac. I then bumped the desired temp up ten degrees and quickly got out, closed the door and checked the Ac clutch. It was still engaged. I then turned it up to 90 In the car and observed the same lack of disengagement. I waited a few minutes each time. My dad is going to be out of town all of the week after next, so it's going to the shop then and I'll just use his car. Might be time to renew all the rubber bits in the front end as well. This could get expensive.

 

[triz]

I'm kind of confused a bit. It sounds more like your fan clutch is engaged all the time? The Jet engine sound?

 

[Steveinfl]

The Ac clutch only turns on and off via the in cabin switch, it does not cycle normally once the desired temp has been reached.

The fan clutch is engaged 100% if the time that the Ac is turned on.

Both issues started at the same time.

 

[BRomanJr]

The Ac clutch only turns on and off via the in cabin switch, it does not cycle normally once the desired temp has been reached.

The fan clutch is engaged 100% if the time that the Ac is turned on.

Both issues started at the same time.

If your system is not cycling at all, then the cycling switch is stuck closed or the wiring is damaged or modified.

Probable that the system got low on freon and someone jumpered the cycling switch to keep it running instead of troubleshooting it properly.


Have you owned it since new?
Did you have it worked on prior to this for a "no cooling" problem?

 

[Steveinfl]

I've had it since day one for all essential purposes. Even when it was my dads car I did some of the maintenance on it. I haven't modified the Ac in any way. I have no doubt that the pressure switch may have failed. I will order and replace that part. The Ac doesn't seem to be functioning as well as it previously had, but it's been almost 100 degrees out every day for the past two weeks, so it is hard to tell. Low pressure side of the Ac reads approx 45 psi. I haven't the tools to check the high side.