Front A/C condenser air flow.

[86 911 Targa]

^^^^^
It has been suggested on a previous post
that cutting 1-1 1/2 inch round holes across the
front condenser shield improves cooling.

I can't find the post.

Any thoughts?

Thanks in advance.

Gerry

[Bob Kontak]

Can't you just remove it?

[Nick Triesch]

Gerry, I just serviced my 85 AC and it works well! But not well enough to take on a drive in the heat. I get 55 through the tiny vents on a hot SO Cal day. Terrible AC . I just drive when it’s cooler in the morning or evening.

[86 911 Targa]

Originally Posted by Bob Kontak

Can't you just remove it?

That has certainly been under consideration.

But, it also acts as a stone guard,
so decisions-decisions...........

Best.

Gerry

[DRACO A5OG]

Hey Doc G,

Replace with chicken wire mesh, paint it black and you will still have some protection. :-) Not Concours but you may get a few degrees lower temps :-)

[Bob Kontak]

Originally Posted by DRACO A5OG

Hey Doc G,

Replace with chicken wire mesh, paint it black and you will still have some protection. :-) Not Concours but you may get a few degrees lower temps :-)

Hardware cloth is a touch beefier/less wiggly. You could probably form it to replicate fastener mounts given proper gauge.

Good idea.

[86 911 Targa]

Originally Posted by Nick Triesch

Gerry, I just serviced my 85 AC and it works well! But not well enough to take on a drive in the heat. I get 55 through the tiny vents on a hot SO Cal day. Terrible AC . I just drive when it’s cooler in the morning or evening.

Why don't you post your A/C configuration for constructive comments?

Gerry

[RNajarian]

I went underneath my car this weekend and saw a new dent in my stone guard. Not sure how it got there but sure glad as hell that it was.

I say go the Tim “The Tool Man” Taylor route, MORE POWER! Try and find a front blower motor that puts out more CFM than the one you have. I am not sure what our squirrel cage blowers put out but I know there are 12V DC blowers that can do 450 CFM

[kuehl]

Originally Posted by 86 911 Targa

^^^^^
It has been suggested on a previous post
that cutting 1-1 1/2 inch round holes across the
front condenser shield improves cooling.

I can't find the post.

Any thoughts?

Thanks in advance.

Gerry

I'd suggest before you go cutting any holes you get some empirical data: using an anemometer to measure air flow; create a grid of cells and measure the air flow in each cell.

[86 911 Targa]

Originally Posted by kuehl

I'd suggest before you go cutting any holes you get some empirical data: using an anemometer to measure air flow; create a grid of cells and measure the air flow in each cell.

Hello Griff,

And thanks for your thoughts.

Having compared (just by hand), the airflow does
increase without the factory screen by quite a bit.

Some of the airflow may be getting trapped between
the condenser and the screen.

Unfortunately, there no way to measure A/C
performance with, or without the screen under identical
ambient conditions.

Best,

Gerry

[kuehl]

Originally Posted by 86 911 Targa

Unfortunately, there no way to measure A/C
performance with, or without the screen under identical
ambient conditions.

Best,

Gerry

Wrong.
You can observe the high side pressure, if it drops then in theory
you have an improvement.

Loosen the 3 ten mm head bolts that hold the perforated grill.
Toss on your gauges. Note the high side reading at idle when clutch
is engage. Remove the grill, and use one fastener on each end to hold
up the condenser. Observe the gauge readings.

Griff

[86 911 Targa]

Originally Posted by kuehl

Wrong.
You can observe the high side pressure, if it drops then in theory
you have an improvement.

Loosen the 3 ten mm head bolts that hold the perforated grill.
Toss on your gauges. Note the high side reading at idle when clutch
is engage. Remove the grill, and use one fastener on each end to hold
up the condenser. Observe the gauge readings.

Griff

I'll give that a try today.

And, thanks again.

Best,

Gerry

[T77911S]

i would put a fan in front of the car to simulate driving conditions.

check hi side as suggested, at a steady 1500 or 2k. then remove the cover and check hi side again.

[kuehl]

Test for the worse case scenario.... not when the car is driving down the road,
not with fans that are not there when you are driving, and not at 2000 rpms.

Idle, at stop light is the worse scenario.
Driving slowing in traffic is the second worse scenario.

[T77911S]

the system was designed to work when driving,.
the compressor is turning too slow, and air flow is inadequate at idle and sitting.

you also spend most of your time moving, not sitting so why test it sitting or charge it at idle and with very poor air flow. AC in a Porsche was an after thought and the design reflects it, also lack of space.

if the guard does not restrict air flow when driving but does when sitting, leave it on. it protects the coil.

just so you know I have been to HVAC school and I am not just blowing hot air.
you check load current of both evap motor and comp along with clean filters to make sure there is proper air flow and the comp is operating as it should be.
same with cars, the comp needs to be above idle and with the very poor air flow on the coils of the 911 extra air flow is needed for them to operate as designed.

[kuehl]

Originally Posted by T77911S

the system was designed to work when driving,.
the compressor is turning too slow, and air flow is inadequate at idle and sitting.

I would not say it was "designed" to work when driving.
True, refrigerant flow and air flow over the deck lid condenser improve with RPM's,
but the front condenser has a fan sucking air in from behind the front bumper and it blows down over the front condenser ...... because rather than "design" a condenser that gets air force directly through it would required a change in the entire front vehicle looks.

Originally Posted by T77911S

you also spend most of your time moving ,

I would not say 911 owners in LA, Chicago, NY City, or Miami spend more time moving. They spend a lot of time in traffic sitting or moving slow. Hence why they want improvements in product designs and charging techniques which help improve comfort in their situation.

Originally Posted by T77911S

so why test it sitting or charge it at idle and with very poor air flow?

The reason do test and charge at idle is to improve cooling. If you know what you are doing, if you know how to charge with P&T, you will see better overall results.
This you can ask of our clients.

Originally Posted by T77911S

AC in a Porsche was an after thought and the design reflects it, also lack of space.

That is a known, and there are plenty of threads here on PP and Rennlist about that.

Originally Posted by T77911S

if the guard does not restrict air flow when driving but does when sitting, leave it on. it protects the coil.

I don't think I would advise you to drop your guard, at least not in this thread. However if you have ever seen what happens to a condenser under its guard with a simple 5 mph bump over high rail road tracks or a cement parking slab, the guard really does nothing other than help to push what is left of the condenser into the bottom of the tub.

Originally Posted by T77911S

just so you know I have been to HVAC school and I am not just blowing hot air.

And, you have a sense of humor too!

Originally Posted by T77911S

you check load current of both evap motor and comp along with clean filters to make sure there is proper air flow and the comp is operating as it should be.
same with cars.

The Porsche 911/930 does not have filters, there is NO value in measuring the amp draw at the compressor coil, the evaporator motor and the front condenser blower motor when evaluating the effectiveness of the system while there is a load on it because load does not affect their amp consumption. Now, if you are discussing charging, testing or evaluating a typical home or commercial system that is a different discussion; I have helped many HVAC "techs" repair the system on my home; I've helped their crew evacuate the system, charge the system by P&T, explained to many of them the reason the evap coil is freezing is because the system is low on refrigerant because the cond coil had a leak and they did not sniff the outside unit the last time they stopped to fill it, and that the reason the outside cabinet is shaking and the cooling is not as good as before is because they bent one of the fan blades (and they forgot to evaluate it after they replaced the motor; because they were in a hurry, etc), and by the way one of them left their electronic leak detector inside the cabinet but is worthless now because it rusted up from leaving it in the cabinet for 6 months.... on and on, Oiy!

Gee, I'm kinda missing Willy, where is the love?