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slowmover · 01-02-2012, 08:05 PM

The FE improvement will not offset the lack of lube being spread through the A/C system, IMO, if the defrost engagement is disconnected. Potentially an expensive lesson since the de-humidification is beneficial; a double penalty. Figure that an A/C system is good for 6-8 years tops before complete system replacement is favored well above component replacement.

I really can't tell the difference between A/C and non-A/C use for FE. Today's compressors are efficient, and the CTD has power to spare. The old RV2 compressors were another matter. The Owners Manuals in those days recommended the compressor be engaged and run while above 30-mph for a good while at least monthly in cool weather. IIRC, the auto-defrost engagement of the A/C cooling showed up in the late 1960's/early 1970's.

We also got in the habit of running the heater in the "summer" in the same way. Seals, manifold doors, fluids all benefit.

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01-02-2012, 08:05 PM	#7 (permalink)
slowmover Banned Join Date: Oct 2009 Location: Fort Worth, Texas Posts: 2,442 2004 CTD - '04 DODGE RAM 2500 SLT Team Cummins 90 day: 19.36 mpg (US) Thanks: 1,422 Thanked 737 Times in 557 Posts	The FE improvement will not offset the lack of lube being spread through the A/C system, IMO, if the defrost engagement is disconnected. Potentially an expensive lesson since the de-humidification is beneficial; a double penalty. Figure that an A/C system is good for 6-8 years tops before complete system replacement is favored well above component replacement. I really can't tell the difference between A/C and non-A/C use for FE. Today's compressors are efficient, and the CTD has power to spare. The old RV2 compressors were another matter. The Owners Manuals in those days recommended the compressor be engaged and run while above 30-mph for a good while at least monthly in cool weather. IIRC, the auto-defrost engagement of the A/C cooling showed up in the late 1960's/early 1970's. We also got in the habit of running the heater in the "summer" in the same way. Seals, manifold doors, fluids all benefit. .