ACtion Magazine - May 2012 - (Page 27)
Vacuum: how much is enough?
By Eugene Talley, Assistant Professor of Automotive Technology, Southern Illinois Univ., Carbondale, Illinois
W
hat do you know about vacuum? It works great to clean your carpet or seal the food you buy at the store. How about using a vacuum gauge to check your engine timing?— sorry, am I showing my age? All kidding aside, how many of us really understand the importance of vacuum when it comes to servicing an automotive air conditioning system?
If you ask other technicians what they know about using vacuum during an A/C service you may get a variety of answers: • I do whatever the machine tells me to. • I don’t have time to wait for the system to get into a vacuum; I will lose money.
• I always turn the vacuum pump on for 15 minutes – that is long enough. • I only had the system open for a minute, I don’t need to pull it into a vacuum. If I asked for other comments my e-mail inbox would overflow quickly. The point is that there are many opinions, ideas, and procedures on how to use vacuum during A/C service. This article is not intended to say any one is better than the other, but a report on some of the things I found when I started looking a little closer. First, how do most technicians measure vacuum? Simple, right?— we use a gauge that reads in inches of mercury (inHg). Vacuum is often used to add oil or dye to a system, and pulling a system into a vacuum makes charging it easier. The problem is that the gauges are not accurate enough when trying to ensure a proper repair. So why do we need an accurate reading? ACTION • May 2012 27
Table of Contents for the Digital Edition of ACtion Magazine - May 2012
ACtion Magazine - May 2012
Table of Contents
Outlook
Expansion Valve
Technically RELAY-ted
Under the Southern Cross
Leonard’s Law
Cooling Corner
Virtual View
News & Updates
New Tools and Tricks From the MACS Trade Show
Vacuum: How Much Is Enough?
“Universal” Compressor Oil?
Association News
Quick Check
New Products & Services
Last Watch
ACtion Magazine - May 2012
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