Engine Size: 350
Refrigerant Type: Freeze12
Ambient Temp: 90
Pressure Low: 30
Pressure High: 280
Country of Origin: United States
I was trying to recharge my 73 Corvette's A/C system today. It had been overhauled about 8 years ago still using F12, and seemed to work ok for a couple years, never really cold. Over the weekend it was not cooling much at all, 80F at the vents. Today I purged the system and pulled a 29.8 "Hg vaccum on the system. After the pump was turned off the system held this vaccum for 45 minutes. Upon putting three cans of Freeze12 into the system the vent temperature dropped to 64F. The LP side reading was 30 psig and the HP side reading was 280 psig. I tried lowering the HP side down to 230 psig but the LP side dropped to 16-20 psig. The vent temperature stayed at 64F. I then added another can of Freeze12 and the LP side went back to 28 psig and the HP side went back up over 250 psig, the vent temperature still was reading 64F. So what do I need to do now? The 73 Corvette use a VIR system that has the POA, the throttling valve, drier and accumulation in the same housing. I do not believe there is any part of the VIR that is adjustable. Should I replace the VIR or what?
We don't support or recommend alternative refrigerants, but the system pressures indicate the system should be cooling. Is the suction line cool? If so, try clamping off the heater hoses - hot air could be blending.
The expansion capsule in the VIR could be bad. Try this quick test: With the engine running at 2,000 RPM record your pressures. Now partially cover the condenser with a piece of cardboard to obtain a high side pressure of 350 to 375 PSI (be careful here). If the low side pressure rises, suspect the expansion valve.
If the system is fully charged, disconnect the blower motor wire. If the low side pressure falls below 28.5 psi, the POA capsule in the VIR is likely bad.
Keep in mind VIR and EEVIR components are physically interchangeable, but mechanically different. Your valve could've been rebuilt improperly.
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