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References From Automotive Aftermarket

A 1996 Toyota P/U Truck came in with the 'A/C system not blowing cold' complaint. This was a vehicle line we don't work on much since we are a European shop. But, since it was a friend, you know the drill. Sure, its just like any A/C System, right?

Initial analysis showed compressor not turning on due to low refrigerant. We evacuated & checked for leaks. Vacuum held pretty well, but I knew there was something leaking very slowly. We filled the system & added fluorescent dye then told the customer that he was going to be the test driver for a few days to let the dye do its work.

Three days later, the truck returns with no cooling again. We quickly got out the lights & started scouring over the entire A/C system. Not a stitch of dye to be found... We added a little more dye, filled the system back up with gas (reluctantly), & sent him on yet another test drive. This time the truck worked for about a week. Great. Again, no dye present on anything under the hood. So, thinking now that the leak has to be on the low side of the system, I started taking the dash apart for a visual on the evaporator core. On reaching the core, sort of, I hit what I could see of it with the magic light & sure enough, there was a trace of dye. The problem was, it wasn't exactly clear where it had leaked. It was a kind of a dusting on the outside of the core block.

I ordered a new evaporator core thinking that it just has to be seeping from the middle of the brick. Something kept bugging me about the way the dye looked. It was just weird. Then, I remembered that we have this great tool (Ultrasonic Sensor from CTRL Systems) & thought; this will be a great test. So I filled the system with nitrogen, about 110 lbs for good testing, took the test probe & shoved it into the heater box, right on the core surface. I could hear a leak without any problems, but it wasn't very loud at the core. It was louder towards the engine. What's up with that? A leak in an A/C system inside the car that's not the core?

Using the headphones, it only took seconds to narrow down the source. Turns out, there was a pinhole too small to see in the feeder pipe (manifold set) coming through the firewall, connecting to the expansion valve. Wow, I would have never suspected that. I'm so glad I didn't install that new core. So, I ended up saving my customer some pretty good money on this one, but more importantly to me, this truck was repaired accurately with no come-back.

Great tool. Makes us look really good.
Brad Bean - Dyno Authority, Redmond Washington website