Here is a factual story.
Visited a friend in Antioch, a machinist while purchasing an unsmoggable Nissan for pennies. To return to Mexico and sell the car. Friend's neighbor had a multi-thousand dollar fuel injector cleaning machine (on-car).
"Hey I hear you know electricity" "Rob" asks. "I have a car that is driving me nuts the customer is angry. Step on the throttle and it shuts the AC fan off".
"Rob" has charged the customer hundreds of dollars trying to fix the problem.
I walk over to the car, start the engine, turn on the A/C and sure enough, give it gas and the A/C stops.
I know what the problem is but I want to turn this into a cheapskate game that costs me nothing.
"Say" I ask, those cars over there, the one's with all the dirt on them, what gives?"
"Not fixable" Rob replied
"What do you want to diagnose and fix this car?"
"How about a full course treatment on your fuel injection cleaner?"
"That's a ninety nine dollars service" Rob explained.
I sighed and smiled and turned to leave
"OK OK" he agreed. "I have to go to court and I'll be back around five"
He leaves. I select one of his junkers sans engine.
I go under the dash and look for vacuum tubing fittings.
I find an Ell non return valve, plastic 1/8".
I get under the dash of the Chevy pickup and install the valve.
Rob returns and was incredulous to find car fixed.
The Nissan enjoys two hours on the SMART injector washer.
NOTE: The "wash" did not make the Nissan smog legal but chopped HC by 60%
Car was purchased for $300 and sold for $1700 in Ensenada. The purchaser was a mechanic who checked tailpipe color which was no longer black.
Should I feel ashamed of myself?
I found "Rob" was a genius compared to some USA "Electrical Technicians"
I can only shake my head.