LS swap - poor A/C performance - The 1947 - Present Chevrolet & GMC Truck Message Board Network

foamypirate · 07-26-2016, 11:48 AM

I just completed my A/C system on my LS swapped 88' Crewcab, and I have to admit, I'm not entirely happy with its performance. The system is all new except for the evaporator, which was flushed. It has an ACDelco parallel flow condenser in it. Compressor is a Denso 10S17F. I used a Ford blue orifice tube, 8 oz of PAG46, and the shop that charged it said they only had to put 32 oz of R134a in the system. I vacuumed the system immediately after buttoning everything up, and the accumulator was the last thing installed. The A/C shop also vacuumed before they charged, per standard procedure. The accumulator and outlet fitting are sweating, and the suction line fitting at the compressor is cold/cool as well. Compressor discharge is hot, condenser outlet is warm. The evaporator inlet, at least where I can feel before I run out of visible tube, is cold. At idle, pressures were about 45-50 low side, 350 high side. I am running 2 LT1 Camaro e-fans with proper fan shroud, and they come on with A/C pressure as they should (controlled by the PCM). Spraying water on the condenser dropped it to ~300-315, which is somewhat expected? At 1500+ RPM, the pressure would quickly rise enough to cut off the compressor via my HPCO (~455 psi, according to the spec). The cooling is OK, but seems like it should be better with a parallel flow and modern compressor. Once the sun went down, I took it for an extended highway drive, and the lowest temp I saw while moving was 51-52*. It actually got slightly cooler at idle - 49* or so. Temps were still in the 90F range.

Another drive during 98F heat resulted in a low temp of 60F after over an hour of driving.

I've tried tweaking the charge a few ounces in either direction without much change.

Am I just expecting too much from the system, or is something wrong? Should I swap the blue orifice tube for a white tube? Is it possible the smaller orifice in the blue tube is artificially increasing my high side pressures?

Let me know if there is any other info I can provide.

07-26-2016, 11:48 AM	#1
foamypirate Registered User Join Date: Apr 2009 Location: Pflugerville, TX Posts: 594	LS swap - poor A/C performance I just completed my A/C system on my LS swapped 88' Crewcab, and I have to admit, I'm not entirely happy with its performance. The system is all new except for the evaporator, which was flushed. It has an ACDelco parallel flow condenser in it. Compressor is a Denso 10S17F. I used a Ford blue orifice tube, 8 oz of PAG46, and the shop that charged it said they only had to put 32 oz of R134a in the system. I vacuumed the system immediately after buttoning everything up, and the accumulator was the last thing installed. The A/C shop also vacuumed before they charged, per standard procedure. The accumulator and outlet fitting are sweating, and the suction line fitting at the compressor is cold/cool as well. Compressor discharge is hot, condenser outlet is warm. The evaporator inlet, at least where I can feel before I run out of visible tube, is cold. At idle, pressures were about 45-50 low side, 350 high side. I am running 2 LT1 Camaro e-fans with proper fan shroud, and they come on with A/C pressure as they should (controlled by the PCM). Spraying water on the condenser dropped it to ~300-315, which is somewhat expected? At 1500+ RPM, the pressure would quickly rise enough to cut off the compressor via my HPCO (~455 psi, according to the spec). The cooling is OK, but seems like it should be better with a parallel flow and modern compressor. Once the sun went down, I took it for an extended highway drive, and the lowest temp I saw while moving was 51-52. It actually got slightly cooler at idle - 49 or so. Temps were still in the 90F range. Another drive during 98F heat resulted in a low temp of 60F after over an hour of driving. I've tried tweaking the charge a few ounces in either direction without much change. Am I just expecting too much from the system, or is something wrong? Should I swap the blue orifice tube for a white tube? Is it possible the smaller orifice in the blue tube is artificially increasing my high side pressures? Let me know if there is any other info I can provide.



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