Is auto-temp control good, or a waste of money?

[blue2000s]

Originally Posted by Jump

OK, I'm curious. What harm does running the AC with the top down cause?

Running the ac pump takes a few hp, using more gas. The pump will also wear out sooner. Also, turning off the car with the ac running leaves moisture in the ventilation system,which contributes to mold growth. This is what makes that sweat sock smell when you first run the fan.

[z12358]

blue2000s:
"Running the ac pump takes a few hp, using more gas. The pump will also wear out sooner."

So how is this different when the top is up? By this logic, running the wipers, playing music, or taking a lady for a ride "takes a few hp, using more gas", too.

Z.

[MNBoxster]

Originally Posted by blue2000s

Running the ac pump takes a few hp, using more gas. The pump will also wear out sooner. Also, turning off the car with the ac running leaves moisture in the ventilation system,which contributes to mold growth. This is what makes that sweat sock smell when you first run the fan.

Hi,

Technically, you're correct. But, also realize that the Compressor on the Boxster is a variable pressure type and can be running anywhere between 5%-100% of rated output depending upon demand (Ambient Temp and desired Temp Setting).

This is to both enhance Range (MPG), and maximize Perfomance (reduced parasitic power loss). But, I think we can all assume that running the AC Top DOWN on a warm day will have it operating at, or near, 100%.

Also, remember to run your AC at least 2 min./mo. (top UP or DOWN) to circulate the Compressor Oil though the system for both the Compressor and also to delay drying out of the 'O' rings.

It's certainly true about the Sweat Sox in the Vent system though...

Happy Motoring!... Jim'99

[blue2000s]

Originally Posted by MNBoxster

Hi,

Technically, you're correct. But, also realize that the Compressor on the Boxster is a variable pressure type and can be running anywhere between 5%-100% of rated output depending upon demand (Ambient Temp and desired Temp Setting).

This is to both enhance Range (MPG), and maximize Perfomance (reduced parasitic power loss). But, I think we can all assume that running the AC Top DOWN on a warm day will have it operating at, or near, 100%.

Also, remember to run your AC at least 2 min./mo. (top UP or DOWN) to circulate the Compressor Oil though the system for both the Compressor and also to delay drying out of the 'O' rings.

It's certainly true about the Sweat Sox in the Vent system though...

Happy Motoring!... Jim'99

The variable load ac systems will also reduce their draw when you open the throttle fully to allow max power to the wheels. But in general, it's using up hp.

I'm not sure where the 2min/month # comes from but it probably is good for the pump seals to get some lubrication.

To prevent the bad smell from the vents, run the fans at full blast without the ac on for a couple of minutes before turning the car off. It dries the water out of the ventalation system.

[MNBoxster]

Originally Posted by blue2000s

...I'm not sure where the 2min/month # comes from but it probably is good for the pump seals to get some lubrication....

Hi,

From the Dealer Service Manual. It says to run the AC for 2 min. for fully circulate the Compressor Oil. This is because the Compressor Oil - ND 8 (a synthetic), has poor mutual solubility with the refrigerant (R-134a). It is moved through the system by the R-134a, and it takes this long to transfer the required amount through the system.

Most Compressor Oils, and ND 8 in particular, are somewhat chemically unstable. If left static in the system, it will react, particularly with metals like Steel and Copper (found in the Compressor). It's acidity rises with this reaction, and this can attack the system's components over time. So this is one reason you want to operate the system for at least 2 min./mo., to circulate the oil away from the compressor to other parts of the system.

Also, when installed, the 'O' rings at the various junctions in the system are coated with fresh compressor oil to keep them from reacting with the refrigerant, which effectively dries them out. By running the compressor at least monthly as described, you give these a fresh coating of oil, extending their lifespan.

Finally, if left stagnant, the Oil lubricating the compressor will settle, creating dry spots on bearings, compressor vanes, etc. This will accelerate wear to the compressor and it's internals. Again, circulating the oil keeps these dry spots from occuring.

I am EPA 609 Certified. A very easy and inexpensive process. I did it several years ago to be able to purchase R-12 OTC, to maintain my Esprit and my Datsun 240Z for about 1/3 the cost of having a shop do it. I took an exam online (after reading the text book from the Library), passed, getting more than the required 21 of 25 questions correct, paid my $15 and received my certification. Anyone can do it, though I see the cost for the exam has risen (like everything else) to $19.95. If interested, check it out at: http://www.epatest.com/e_609cert.html . Hope this helps...

Happy Motoring!... Jim'99

BTW, Good advice on drying out the vents!