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A burned clutch is a symptom of another problem

By Richard Hawkins, MACS Contributor

很多年前,我去了一个空调诊所,里面有一张幻灯片标题是: A burned clutch Is a symptom of another problem stuck in my memory. 当我开始接听技术电话时,它经常成为讨论的话题.  See picture #1.

Picture #1:  A clinic slide like the one I saw years ago.

没有太多的考虑,直到他们失败,但他们是非常耐用的压缩机离合器.  我个人拥有三辆车,行驶里程在20万到24万英里之间.  它们都还保留着原来的压缩机和离合器,而且它们仍然运行得很好.   也, 多年来,kok体育安卓版下载在技术电话上进行了多次交谈,发现里程相近或更高的汽车,其原有的压缩机和离合器功能都很完美.

Traveling down the road at 55 to 60 MPH, an engine will typically be turning about 1,800 to 2,000转, depending on the vehicle, engine size, gear ratio, 等.  When the clutch engages, 它立即从静止加速到离合器滑轮旋转的速度.   On a high mileage vehicle with a cycling system, the compressor might have engaged and disengaged more than 100,000倍.  能够承受这种惩罚简直令人惊讶.

Back in the “good old days”, 离合器更换是一个流行的事件时,有一个离合器问题.  Nowadays, changing a clutch seems to be a rare occurrence.  这是因为离合器是不可用的很多压缩机.  也, if they are available, 带有离合器的压缩机的成本通常比单独使用离合器和更换离合器的劳动成本要低.

On a tech line, burned clutches are a commonly encountered issue.  Often a conversation will go something like this:

Technician:  在过去的十天里,我在这辆卡车上安装了三个你们的压缩机,但离合器一直在烧坏.  Why are your compressor clutches so “sorry”?

Me:  车辆来维修时更换原压缩机的原因是什么?

Technician:  The clutch was burned up on it.

Me:  那辆卡车上有四个离合器被烧毁,而不是三个.

Technician:  Well yes.  但原来的那辆不算因为卡车已经跑了十万多英里了.  The clutch just wore out. 

Me:  也许, 但更有可能的是,有一个问题,导致离合器在原来的压缩机失效.  这个问题仍然存在,这是什么是导致离合器更换压缩机燃烧.   烧了, 这些离合器变得非常热,它们变热的原因是它们在滑动.  See picture #2 below.

Picture #2:  A slide from a MACS clinic.

Technician:  OK, go on.

Me:  Did any of the four compressors lock up?

Technician:  No.

Me:你检查过离合器气隙和更换压缩机上的线圈电阻了吗?

Technician:  No, 这个间隙应该在工厂设置,线圈应该有合适的电阻.  

Me:  是的, 气隙应该在工厂设置正确,线圈应该有正确的电阻.  然而,有时离合器结束与一个不正确的气隙和/或线圈与太多的阻力.  As a result, 压缩机安装前应检查离合器气隙和线圈电阻.  These conditions can cause clutch slippage, 但你们收到三个有这些问题的压缩机是极不可能的.  这又指向了一个导致离合器燃烧的问题.  See picture #3 below.

Picture #3: A clutch with bearing damage due to excessive heat.

Technician:  OK, so what do you think the problem is?

Me:  There are several reasons compressor clutches fail.  They include, low available voltage, high resistance ground, liquids on clutch surfaces, air gap too wide, blocked or internally plugged condenser, cooling system problem, bad fan clutch, high side restriction, overcharged system and lack of lubrication.

Based on the information you’ve supplied, high side pressure being too high, and voltage and ground issues would be the most likely culprits.  See picture #4 below.

Picture #4: Another slide from a MACS clinic.

Technician:  The pressures were OK when the system was functioning, so it sounds like I need to focus on the voltage and ground areas.

Me那将是一个很好的开始,但不要完全排除其他事情.  也, heat brings out the worst in electrical systems.  在启动后,当一切都很酷时,立即进行电气测试并记录结果.  然后让一切达到操作温度,并把空调系统在一个高热负荷的条件下,再次做测试,并比较结果. Then is when you are most likely to find something.

Whenever a compressor or compressor clutch fails, 有必要确定原因并纠正它,否则可能会发生另一次故障. This is called “Root Cause Analysis“.   只是更换压缩机而不确定故障的根本原因,只是治标不治本.

Technician好的,我再换一次压缩机,检查一下.

Me: Be sure to do a proper oil balance, 检查离合器气隙和线圈电阻,并打磨离合器.  抛光离合器将几乎立即增加扭矩能力的离合器约20%.

Technician:  What do you mean “burnish the clutch”?

Me:  It is sort of like breaking in a new set of disc brake p广告. 

I proceeded to explain the process.  See picture #5 for information.

Picture #5:  Clutch burnishing explained in a slide from a MACS clinic.

Editor’s Note:

Richard Hawkins will be presenting the class Behavioral Characteristics of Various Compressor Types at MACS 2021 kok下载安卓版 Event and Trade Show. Don’t miss the valuable knowledge Richard has to share. You could save your self hours of diagnostic time. Register here to attend MACS 2021 kok下载安卓版 Event and Trade Show, Sept 30-Oct 2 at the Rosen Centre Hotel in Orlando, FL.

One response to “A burned clutch is a symptom of another problem”

  1. Thomas C Potter 说:

    I know of one other clutch failure, 中心阻尼器过热,有时看起来像一堆小橡皮球. 检查压缩机时,压缩机没有锁紧,系统没有过充. 如果你把一个新的离合器在压缩机上,同样的故障发生在大约一到两个月.
    What causes this failure. I know, but does Richard Hawkins know?
    Note: this is on DENSO compressors.

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