88-94 5.7 Suburban A/C Diagnosis and Tuning

@L31MaxExpress To be honest, I'm glad this chapter of my wrenching life is closed. I'm afraid to tally up the number of hours and $ I put into this thing, but I'm too stubborn to call it quits until the job is done. Sure did learn a ton, with alot of help from the community. I won't remember the cost in a couple months but I'll enjoy the cold air every day on the way back home from work!

This old TBI 350 definitely feels the extra load on it, I'll track mileage and see how it does vs the single V7 which was pulling 13-14 MPG. Foreshadowing the future couple months, I've got a built ~420hp 406ci SBC just itching to get thrown in the burb. The 4L60e is due for a refresh, and I plan on installing a 9.75" HD 6 lug rear axle from the 2014-18 silverado pickups to deal with the increased power.

jd33173 said:

Do you have a one wire cable to plug into the high pressure switch the back of your compressor?

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The V7 does not have the rear switch in them, the V5's and R4's do from my research. I added an inline switch on the high side hose enroute to the condenser. I really like the Supco SHP series switches, very clean cut out and cut in.

Wildblue19 said:

This old TBI 350 definitely feels the extra load on it

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How many BTUs can you pump with that dual-everything setup, 36,000? More?

I wonder how many passenger vehicles have 3T+ of AC capacity.

IIRC the spec on my 1998 Honda is 15,000BTU.

1998_K1500_Sub said:

How many BTUs can you pump with that dual-everything setup, 36,000? More?

I wonder how many passenger vehicles have 3T+ of AC capacity.

IIRC the spec on my 1998 Honda is 15,000BTU.

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Each V7 is capable of something like 47,000 BTU. Not sure what the evaporator core limit is.

My aftermarket rear ac unit in the Express is rated 13,000 BTU alone. Front unit is probably 24-30K on most GM trucks, SUVs and Vans. The older A6 compressor moved 42,000 BTU.

You guys ever look into the larger Sanden (or other) scroll compressors?

The Sanden p/n 4910 is rated at 121cc/rev.

It's a member of the Sanden TRSA12 family (performance curve attached).

The performance curves for the scroll compressors are incrementally more efficient (COP) at higher RPM relative to the piston designs... which is no surprise (see the family of performance curves, attached).

They're not as efficient at lower RPM, as the curves show; this isn't a surprise either.

@Wildblue19, you mentioned engine load in your post.