We’ve all been new at one time or another, so there is no need to judge others about some of the mistakes new techs make. However, there are some very preventable mistakes that occur due to simple oversight and carelessness. Here they are:
Leaving caps off is never OK. While it’s true that Schrader valves and back seating service valves “should” seal completely and shouldn’t be left leaking, it is always possible that a little leakage can happen. Besides, keeping bugs and dirt out of the ports is reason enough to keep the caps on.
Bill Johnson (co-author of RACT) made a really good point on a recent podcast. When a system is apparently low (which you can verify through non-invasive temperature tests) you shouldn’t just pull off the caps and attach the gauges. First, look for oil at the ports and leak check them to eliminate port leaks as a possible cause. Once you remove the caps and attach your manifold, you won’t be able to know if the ports were a leak point or not.