I was adding some R134a the other day and came up with an idea-wrap the A/C lines with insulating reflective silver tape. The low pressure line connects to the compressor right next to the exhaust and near the radiator. If you wrap the lines with insulating tape, you should keep the lines cooler.

This should be good for cooling down the air a few degrees, especially in stop and go traffic when the cooling fan comes on all the time.

 

How do you know your R134a is low? My AC doesn't feel as cold as it should be.

 

You can get one of those 'self recharge' kits that has the little gauge attached to the hosing.

 

^
yep did this for 1st time 3 weeks ago...can cost like $25 from Murray's...

 

Is this easy to do? Not too mechanically inclined here...

 

Actually, very easy...I have had to do it a couple times to my Ram which I don't feel like spending $$$ on repairing.

 

I remember on g35driver.com the people there wrapped their metal AC lines with this rubber foam kind of tubing, to which they say the AC is now colder.

 

I don't think it would help. If it did, don't ya think the manufacturer would have done that?

A properly functioning AC system will cycle the compressor on and off ayways. There's a sensor built into the evap side to shut the compressor off to prevent freezing the line. Hard to tell in the Max, but the compressor does cycle, at least on mine it does. That's how I know the system is working at it's best, because if it weren't, the compressor would never shut off, or it cycles too fast and doesn't get cold.

 

Blowing hot air over lines that have A/C coolant in them can't be good for efficiency. Especially lines that are made of aluminium which does a very good job at transferring heat.

 

I'm sure the engineers that design these know that. There must be a good reason why not a single car ever made came from the factory with those line insulated.

 

You know this for a fact??

 

if the engineers were that flawless in their planning then no rotors should warp prematurely. this is just one of numerous examples but also consider they must work within a budget. if they can get the air cool as on previous models then the job is done. if someone can/has figured out a way to lower the air temp a few degrees then more power to them. the same principle holds true on ac lines to a house. there is a reason for insulating them. for 5 bucks of 30ft wrapping from lowes then its worth it for me to try.

 

Engineers don't get to implement everything they want either because of costs or other considerations. I'm sure that nissan engineers know that headers would improve performance but don't use them because of cost. If engineers weren't constrained by cost, you would get something as expensive as a Porshe or a Ferrari.

In warm weather, this probably wouldn't make much of a difference. But here in the west right now, there's a big heatwave. It's been about 105-110 lately where I live and the A/C isn't quite up to the task. If this could lower my temps by a few degrees for $5, than it's worth it.

 

Speaking on behalf of engineers, no, you cannot put every little $0.02 worth of improvements into a car. The a/c was likley deemed as being 'cold enough' for the cost at time of production, hence why they did not provide additional mechanical improvments to the system, thereby reducing total cost.

 

http://g35driver.com/forums/showthre...ighlight=a%2Fc

 

..thanks for finding it.

 

Can someone give me he Cliffs' Notes? I am not going to join to read a single thread

 

It basically says the same things that are said in this thread. A few people there tried it and it did cool down the air a bit.

 

Older Mercedes and BMWs wrap their refrigerant lines (which incidentally were intertwined with the fuel lines on older models). Someone try, and report the #s from the a/c test mode.

 

Our cars use a variable displacement compressor, so the clutch is always engaged, ie always on, UNLESS you have low outside temps, low refrigerant, main switch or fan switch is turned off, and I also think under high engine load/WOT. Anyways, if you're hearing your compressor kick on and off, you'd better check your refrigerant.

The compressor is turning low pressure gas into high pressure gas, which adds a lot more heat then ambient temp adds. Even if you could make a significant temperature difference, by definition of PV=nRT, our variable compressor would just compensate by adding more heat by trying hold the same pressure.

At least that's what my half-fried brain says when reading the FSM A/C section.

 

Trying to properly test that would be tough. Climate control may not be blowing straight through the evap if the car is out of the sun or outside temp sensor is reading something different then your test before you wrapped the lines.

Automotive AC is designed to run colder than residential AC. WHere a residential AC will blow about 55^ at the vents, car AC will be down around 32-36 at the vents if you are blowing straight through the evap. As is, they run close to freezing the evap and lines, I just don't think you guys are going to get much more out of it by insulating. If it's working right to begin with, a car AC can't get much colder. In my other car, I keep a thermometer in the vents, and when it's cooled off, the vent temp is 32-35. To get colder then that you'd end up freezing the evap and the cold side sensor just won't let that happen.

 

To be honest I've never been able to tell with my Max. My other car does cycle the clutch and I can feel that when I'm driving it. I'm glad the max has the variable displacement thingy because when the clutch engages and disengages on the other type, it's harsh at times.

 

I wish we had a "that went right over my head" smilie....

 

The FSM quotes vent temperatures only 30-40 deg below that of the air that passes over the evaporator.

Maybe I have something wrong with my A/C, but with this 105deg weather, my car never cools off enough to be comfortable. I think I would kill for vent temps of 32-35deg, I think I prolly have 70-75 when the outside temp is 105.

 

[QUOTE=IceY2K1]
The compressor is turning low pressure gas into high pressure gas, which adds a lot more heat then ambient temp adds. Even if you could make a significant temperature difference, by definition of PV=nRT, our variable compressor would just compensate by adding more heat by trying hold the same pressure.[QUOTE]

The compressor doesn't really add "heat," it compresses the low pressure gas which in turn increases its temperature and pressure. I guess the line going from the condensor to the evaporator is what would need to be insulated.

In thinking about this more, the line that goes from the evaporator back to the compressor should NOT be insulated. In fact, the more heat that is added to it, the better since the compressor wouldn't have to compress the gas as much to attain the same temperature and pressure.

 

And that's in a car that has 150k miles on it, and is 11 years old. And I've never recharged the thing. Even on days in the mid 90s when the car's been in the sun for 8 hours. On the the worst of days, the temp guage in the vent will read 140^F when I first get in the car. When it's that hot it will take about 15 minutes to get down to 35^ or so but it does. It's not R12, it was one of the first R134a cars, back in 1994-95.

I've never checked the vent temp in my Max but that get's cold too.

 

GUYS...GALS....BE SURE YOUR CABIN AIR FILTER IS CLEAN!!

A CLOGGED CABIN AIR FILTER WILL RESTRICT COLD AIR...CAUSING YOUR SYSTEM TO WORK HARDER!!

CHANGE THE FILTER...AND THE COLD AIR WILL FLOW IN EASIER!!

On a different note: I had tough problems cooling my Bonneville..like all the time. It was really pitiful even after recharges!

I did wrap the "cold" line into the firewall-it did help. I ALSO applied the foam tape insulation around the firewall where the air conditioner was. I did everything to limit hot air contact with the cool areas.

Do it...you can make a difference!


.

 

Nice enthusiasm and animation! ha

 

Dude,

Your caps quote made my day-Thanks.