Checking the clutch air gap before installing a compressor is an important step in compressor installation. This is because of the possibility of a clutch air gap getting knocked out of adjustment due to rough handling or it being gapped incorrectly at the factory. 这些问题当然可以导致问题与离合器操作. If detected and corrected before compressor installation, a lot of time can be saved.
There are two other “right out of the box” clutch issues that are encountered with some regularity on tech line calls. 这些都是:
1. 完全没有离合器功能. (通常是由于“开”离合器线圈.)
2. 空调压缩机离合器回路吹断保险丝. (通常是由于离合器线圈电阻太低.)
作为一个结果, it is advisable to do some other tests while you have the compressor on the bench checking the clutch air gap.
对离合器功能的台架测试很容易完成. This can be done by simply putting power and ground directly to the clutch coil. This can be done utilizing a battery and test wires or a power probe. 如果使用测试线, an in-line fuse holder with a 10-amp fuse should be utilized for protection and the test wires should be 16 gauge or larger. 一接通电源，离合器就应啮合. 断电时，应立即断开. 注意:在做这个测试时，必须观察极性. If the wires are connected wrong and the clutch coil uses a diode, diode damage will result.
The most common cause of compressor clutch circuit fuses blowing is a compressor clutch coil having a resistance value which is too low. Taking an ohmmeter and checking the clutch coil resistance will quickly tell you the resistance. If your information system provides the resistance value for the specific vehicle you are working on, 最好使用它. 然而, it does not seem to be readily available for very many vehicles.
Fortunately, the mobile A/C industry provides some guidelines on this. If you search Google for “A/C compressor clutch resistance” there are several articles that come up with clutch coil resistance information. Unfortunately, there isn’t universal agreement on the specifications. 将会看到的一些范围是.0到4以下.5欧姆”、“2.8 to 4.4欧姆“，”大约3.0 to 4.0欧姆”,3.0 to 5.0欧姆，然后最宽的范围是2.0 to 5.0欧姆”. A short discussion with someone working on a tech line also yielded the answer: “4 ohms plus or minus 1 ohm” (which of course is the range of 3.0 to 5.0欧姆.这些值仅适用于12伏离合器.)
Utilizing all that information, the lowest acceptable resistance value would be 2.0欧姆，可接受的最高电阻值为5.0欧姆. So, two lines could be drawn in the sand there with anything that checked below 2.0欧姆或以上5.0欧姆不符合条件. (Keep in mind that these resistance values are at room temperature. Resistance readings taken at extreme temperatures can be affected. 较低的温度会使电阻下降. 温度越高，电阻就越高.)见图1.
Picture #1: An ohmmeter test of the clutch coil can tell you if resistance is within an acceptable range. 然而, be sure you have good connections or the readings on the meter may be misleading. 许多离合器有两根线连接. The one in this picture has one wire and is grounded through the compressor case.
But you might say: That leaves a lot of grey area with all the other ranges that fall within the 2.0 to 5.0范围. kok体育安卓版下载如何解决这个问题? Taking all of that into consideration, the “sweet spot” seems to be from about 3.5 to 4.0欧姆，所以这是一种判断. 如果你检查离合器线圈电阻，它是在3.5 to 4.0欧姆, it would be a good idea to contact the compressor supplier and see what they say.
Some technicians like to go a step further and check the amperage with an in-line amp meter. To determine what the amperage should be, we would use Ohms Law: Amperage = Voltage divided by Ohms. 这里有一个例子使用充满电的电池与12.65伏特作为电源和离合器线圈与4.0欧姆的电阻.
12.65 ÷ 4.0 = 3.1625，所以安培数刚好超过3安培.)
就像气隙问题一样, clutch coil resistance issues and non-functioning clutches are not an everyday thing. 然而, 如果你做足够的空调工作, it is highly likely you will encounter a non-functioning clutch or clutch coil resistance issue somewhere along the line. 这是命运的安排, it will probably be on a vehicle where the compressor is buried and removing and re-installing another compressor might take hours. You’ll find taking a few minutes to check clutch function and the clutch coil resistance can prevent this from occurring.
An excellent article on clutch function can be found at the following link: http://www.macsw.org/WEB/images/Macs_Docs/2019TETS/TCCI.PDF
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