11/30/2023 0 Comments Clutch burn out![]() These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. See picture #5 for information.Īnalytical cookies are used to understand how visitors interact with the website. ![]() Me: It is sort of like breaking in a new set of disc brake pads. ![]() Technician: What do you mean “burnish the clutch”? Burnishing the clutch will almost immediately increase the torque capability of the clutch by about 20%. Me: Be sure to do a proper oil balance, check the clutch air gap and coil resistance and burnish the clutch. Technician: OK, I’m going to replace the compressor again and check those things out. Just replacing the compressor without determining the root cause of the failure is just treating the symptom. Whenever a compressor or compressor clutch fails, it is necessary to determine the cause and correct it or another failure is likely. Then is when you are most likely to find something. Then get everything up to operating temperature and put the A/C system in a high heat load condition and do the tests again and compare the results. Do your electrical testing right after start-up when everything is cool and record the results. Also, heat brings out the worst in electrical systems. Me: That would be a good place to start, but don’t totally rule out the other things. Technician: The pressures were OK when the system was functioning, so it sounds like I need to focus on the voltage and ground areas. Picture #4: Another slide from a MACS clinic. They include, l ow 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.īased on the information you’ve supplied, high side pressure being too high, and voltage and ground issues would be the most likely culprits. Me: There are several reasons compressor clutches fail. Technician: OK, so what do you think the problem is? Picture #3: A clutch with bearing damage due to excessive heat. To burn up, those clutches got extremely hot and the reason they got hot was because they were slipping. That problem is still present and that is what is causing the clutches on the replacement compressor to burn up. Me: Well maybe, but it is much more likely there is a problem there that caused the clutch on the original compressor to fail. But the original one doesn’t count because the truck has over 100,000 miles on it. ![]() Me: So, you have had four burned clutches on that truck instead of three. Technician: The clutch was burned up on it. Me: What was the reason the original compressor was replaced when the vehicle came in for service? Why are your compressor clutches so “sorry”? Technician: I have installed three of your compressors on this truck in the past ten days and the clutches keep burning up. Often a conversation will go something like this: On a tech line, burned clutches are a commonly encountered issue. Also, if they are available, it often costs less for a compressor with a clutch than it does for a clutch by itself and the labor involved to change it out. This is because clutches are not available for a lot of compressors. Nowadays, changing a clutch seems to be a rare occurrence. Being able to withstand this kind of punishment is nothing short of amazing.īack in the “good old days”, clutch replacement was a popular occurrence when there was a clutch issue. On a high mileage vehicle with a cycling system, the compressor might have engaged and disengaged more than 100,000 times. When the clutch engages, it accelerates instantly from a dead standstill to the speed the clutch pulley is turning. Traveling down the road at 55 to 60 MPH, an engine will typically be turning about 1,800 to 2,000 RPM, depending on the vehicle, engine size, gear ratio, etc. Also, over the years numerous conversations have occurred on tech calls where vehicles with similar or higher mileage had the original compressors and clutches functioning perfectly. They all still had the original compressors and clutches, and they were still functioning perfectly. I have personally owned three vehicles that had between 200, 000 and 240,000 miles on them. Not much thought is given to compressor clutches until they fail, but they are extremely durable. Picture #1: A clinic slide like the one I saw years ago.
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