Air conditioning repair

I haven't owned a car yet that had an adjustable expansion valve.

And system pressures are almost useless except if your looking for gross problems like a completely plugged line. What you are looking for is measuring the temp differential between the freon going into and coming out of the different parts of the system. The pressures are very much affected by variables like humidity, air temp, temp inside the car, outside the car, etc. Some manuals do have tables of pressures that list the major affecting variables, these are somewhat useful.

And you also should not add freon to a system lacking a sight glass like this. The by the book procedure is to completely evacuate the system. Then refill the system with the designated volume of freon the system was designed to hold. You can also try adding refrigerant gradually until the temp differentials are where they are supposed to be, of course this only works if the system is in running order.

conditioner.

In all of the cars I've owned when the A/C compressor had problems it self-destructed throwing junk into the freon lines. I'd have loved it if only a bearing in the compressor failed.

Pretty inefficient when you can use an electronic freon leak detector to find the leak. And if you pull apart a sealed joint to replace an O ring the joint may not reseal correctly. Better to only mess with the joints that are leaking.

Many cars also do not use o-rings they use flared fittings.

Your lucky. Sometimes when hoses leak like that they lose bits of the hose into the freon line which will plug the screen on the expansion valve.

The explanation of how the AC system works is in the factory service manual It's also on the backside of the recharge kits in the auto parts store. This young tech was no tech if he thought he could repair anything without reading the manual.

The government wants trained individuals to work on R12 systems due to the environmental contamination. They don't care if idiot techs do shit like this with R134a systems since R134a sales are not restricted. Further R134a is used as an expansion gas in foam insulation, and a propellant in asthma inhalers. Those sources dump hundreds of tons of R134a into the atmosphere every year, dwarfing that produced by leakages from auto A/C systems.

You may know the theory but you seem to lack practical experience in current repair techniques. You would probably benefit from spending some time reading many of the online sources out there for that. You might also benefit from reading the EPA regs covering A/C work. The fact you didn't mention sight glasses or electronic leak detectors has me wondering.

Ted

R134A is benign until heated. It doesn't burm, but DOES produce poisonous gas by thermal decomposition.