Wow that’s a home run. Really blows away my hillbilly plan.
Yes since my car had a working factory A/C setup I ordered up a flush kit for the evaporator to clean it out of any/all R12 that was in there before I did the new install.
Ron,Back in the late 70's on a humid day my Charger(Factory air) would freeze if I ran it too long on Max air.
Out of curiosity, was the system a R-134A retro fit? If so, did you REMOVE the Evaporator Pressure Regulator in the suction inlet to the compressor, if it is the V2 unit? If it's the Sunden compressor system, did you install a new Thermostatic Expansion Valve (TXV) that is compatible with the refrigerant used (assuming R-134A) as this controls the liquid refrigerant entering the Evaporator. Too much refrigerant will cause flooding and subsequent freezing of the condensed water, on the air side, especially with high humidity conditions; conversely, too little refrigerant will cause poor cooling and higher air side temperatures. The TXV controls the amount of SUPER HEAT in the exiting evaporator pressure and temperature. Most, but not all, systems cycle the compressor clutch off/on to maintain an average evaporator pressure of approximately 35-40 psi to yield approximately 38°F - 40° F air side temperature. Perhaps your pressure switch is defective......just a thought. Just my opinion of course,....
I glad you posted this picture of your lines and firewall. I will say the switch they provided is similar to yours but not the same exact (probably just a different vendor) I have my switch secured off on of the fan motor studs hoping to hide it a bit and yes then you to that tube along with the capillary from the expansion valve. I know I used a worm clamp instead of their provided piece. I can't swear though if the one from the switch is also clamped to the tube or just held in there by the black tape stuff.
Car has all factory setup. Converted before I got it. They did a poor job, left half or more o rings black or missing. They also left one old line on and painted it. I did all green o rings and changed the small hose, also installed new drier and expansion valve. Guy that charged it added some oil and put in 3 pounds of 134.
Just be careful...some of the newer GM vehicles (Buick), use R-1234Yf refrigerant....totally different chemistry, operating pressures, volumes, refrigerant oil, and seals....look for the ID label...
If you are running the factory style compressor and R-134 freon, there is a EPR valve in the compressor, it was used to control the flow of the freon, it is not compatible with R-134. You have to convert the system to be a cycling type, like all new cars since R-134 was introduced. You may know this information. I have done a couple underhood retrofits and the companies did not explain this at all. If you are using the factory stuff under the dash, you will have to install a switch on the low side under the hood. And remove the EPR valve. The 165 high and 15 low side pressures are both really low with R-134, should be more like 250 and 38 lbs.
I said the same thing back in response #27 re the EPR VALVE. The suction and discharge pressures are temperature related not so much volume related. My readings may be totally different than you readings.....performance is the criteria not so much as achieving a given pressure.....
How would one find said switch? What happens if the epr is left in?
IMO...if the EPR valve is left in service, assuming the V2 compressor, it will act like a restriction to the suction pressure. As the EPR VALVE has a bellows assembly internal to the valve and reacts to pressure changes of R12, and R134A has different pressure characteristics, the valve will not respond correctly, likely causing a restriction and a reduced compressor capacity and a lack of cooling.
