A/C Question

[ganun]

When I replaced the whole air con system last winter with a Retroair, they could not explain why the a/c draws air from the trans tunnel AND the cabin. Seems to me only cabin air should be used, I know this was left over from the gas heater days, but .....nevertheless l left the hole in the bottom of the evaporator box. Maybe for additional air volume????
George

[DRACO A5OG]

Doesn't seem right, OEM does not have plumbing to the tunnel. it should only suck/recycle in from the passenger side foot well, some air seeps up from the drain as well but very minimal.

[wwest]

The second air inlet is at the front of the tunnel, drawing air from the driver's side footwell.

Or so I'm told.

[ganun]

This is what I am talking about, at least the return air from the pass side id behind the foot rest, but the one from the tunnel also gets some air from the drivers right shoe, ....nasty ! I have it in my mind to cut a proper hole on the top side of the tunnel with a nice grille over it .

You can see the round hole going to the tunnel.


Here you can see the bottom of the plastic box where the evaporator coil sits and the round hole is visible, and the trapezoidal opening leading to the pass side foot rest opening. These are the pics of the old a/c unit removed from the car, it awas nasty also!

[Nickshu]

Yes it draws air from both places. Not sure why it's setup like that, seems that the passenger's footwell would be sufficient.

Bear in mind the "transmission tunnel" is basically sealed off and opens into the driver's footwell/pedal cluster area, so in the end 100% of the air going into the evap/blower box is recirculated cabin air. There is no outside or engine compartment air traveling thru the tunnel, provided all the rubber grommets at each end are good.

[JAR0023]

There is an opening on the top side of the tunnel at the front of the tunnel ahead of the console. Peel the carpet back and it's easy to find. This is how you access the cruise control clutch switch. -J

[wwest]

Since colder air settles to the lowest point the driver's feet might "freeze" absent the cabin air inlet from that point.

[quattrorunner]

Originally Posted by wwest

Since colder air settles to the lowest point the driver's feet might "freeze" absent the cabin air inlet from that point.

Freeze? Maybe in the winter.

[pc100porsche]

ganun -- can you comment on the effectivemess of the Retroair System ?
Why did you, personally choose this system over the other couple of suppliers ?

[wwest]

Originally Posted by quattrorunner

Freeze? Maybe in the winter.

Didn't mean it to be taken literally...

[pc100porsche]

Any Triple Black Cars out there with upgraded Aircond That Works -- eager to hear specifically what you installed and result ??

[wwest]

Originally Posted by pc100porsche

Any Triple Black Cars out there with upgraded Aircond That Works -- eager to hear specifically what you installed and result ??

Move to Seattle...

[Chuck.H]

What I believe we need is a re-designed evaporator box. Before I did the Kuel fan upgrade, I made a larger fan box using the blower motor from a Jeep Wrangler; this was ugly but man did it move some air! The Kuel fan motor helps, but it's not enough IMHO. I'm going to build another one that's not so ugly or intrusive, but still allows a larger fan.

Chuck.H
'89 TurboLookTarga, 352k miles

[wwest]

Originally Posted by Chuck.H

What I believe we need is a re-designed evaporator box. Before I did the Kuel fan upgrade, I made a larger fan box using the blower motor from a Jeep Wrangler; this was ugly but man did it move some air! The Kuel fan motor helps, but it's not enough IMHO. I'm going to build another one that's not so ugly or intrusive, but still allows a larger fan.

Chuck.H
'89 TurboLookTarga, 352k miles

When, under what circumstances, does our Porsche's really exhibit the shortcoming(s) of the design??

My answer would be consistent low RPM engine operation in stopped, slow moving stop and go rush hour traffic, and if that isn't enough....HOT August mid-day sun in Houston.

That might be, of course, due to the lack of the compressor not pumping enough refrigerant..

But then what about the "GOOD" reports we get from those that have added some sort of condensor cooling fan capability, fender mount, engine lid, whatever. On top of all that one of the most common "improvement" upgrades, recommended by none other than Kuehl himself, actually LOWERS the compressor displacement.

Maybe based only on theory, but that's why my recommendation is to FIRST add refrigerant condensing capability, or simply increase the efficiency of the condensors already in place.

A few years ago (01?) I purchased, Ebay, a BLACK 1992 Lexus LS400, 120K+. Already owned a '92 at home, purchased new. Flew down to Phoenix to take possesion...found that the windows were tinted dark well beyond the legal level in my home state.

On the subsequent drive south to Tucson it became obvious the the A/C capability was Somewhat lacking. Found an A/C shop in Tucson that told me the system was fully charged, R-12.

Drove over to Fresno, on to Santa Cruz and then home with the A/C just satisfactory, other than SLOW cabin cooldown and an evaporator freeze up (systemic to Lexus) over the pass near shasta. Had it converted to R-134a right away.

Grandson drove it until a few months ago when it was sold.

My point: Even the Lexus, in BLACK, and in hotter climates, needed extra aftermarket efforts to get satisfactory A/C.

TRIPLE BLACK...

Simply enjoy those times you can go with the top down.

[quattrorunner]

Quote de Chuck.H

What I believe we need is a re-designed evaporator box. Before I did the Kuel fan upgrade, I made a larger fan box using the blower motor from a Jeep Wrangler; this was ugly but man did it move some air! The Kuel fan motor helps, but it's not enough IMHO. I'm going to build another one that's not so ugly or intrusive, but still allows a larger fan.



Chuck.H

'89 TurboLookTarga, 352k miles

When, under what circumstances, does our Porsche's really exhibit the shortcoming(s) of the design??



My answer would be consistent low RPM engine operation in stopped, slow moving stop and go rush hour traffic, and if that isn't enough....HOT August mid-day sun in Houston.



That might be, of course, due to the lack of the compressor not pumping enough refrigerant..



But then what about the "GOOD" reports we get from those that have added some sort of condensor cooling fan capability, fender mount, engine lid, whatever. On top of all that one of the most common "improvement" upgrades, recommended by none other than Kuehl himself, actually LOWERS the compressor displacement.



Maybe based only on theory, but that's why my recommendation is to FIRST add refrigerant condensing capability, or simply increase the efficiency of the condensors already in place.



A few years ago (01?) I purchased, Ebay, a BLACK 1992 Lexus LS400, 120K+. Already owned a '92 at home, purchased new. Flew down to Phoenix to take possesion...found that the windows were tinted dark well beyond the legal level in my home state.



On the subsequent drive south to Tucson it became obvious the the A/C capability was Somewhat lacking. Found an A/C shop in Tucson that told me the system was fully charged, R-12.



Drove over to Fresno, on to Santa Cruz and then home with the A/C just satisfactory, other than SLOW cabin cooldown and an evaporator freeze up (systemic to Lexus) over the pass near shasta. Had it converted to R-134a right away.



Grandson drove it until a few months ago when it was sold.



My point: Even the Lexus, in BLACK, and in hotter climates, needed extra aftermarket efforts to get satisfactory A/C.



TRIPLE BLACK...



Simply enjoy those times you can go with the top down.

Car appears to be white

[wwest]

Originally Posted by Chuck.H

What I believe we need is a re-designed evaporator box. Before I did the Kuel fan upgrade, I made a larger fan box using the blower motor from a Jeep Wrangler; this was ugly but man did it move some air! The Kuel fan motor helps, but it's not enough IMHO. I'm going to build another one that's not so ugly or intrusive, but still allows a larger fan.

Chuck.H
'89 TurboLookTarga, 352k miles

There is no question about there being substantial inefficiencies in our evaporator/blower system design. Beginning with RESTRICTED air inflow and outflow for which NO aftermarket fan/blower air movement capability can really overcome.

But, with consistent hwy speeds, elevated engine RPM, if your system cannot maintain the evaporator core at <35F with the blower at high speed and a 72F cabin atmosphere you need to look elsewhere FIRST.

[wwest]

Originally Posted by quattrorunner

Car appears to be white

Was referring to post #11 by pc100porsche...

[ganun]

Originally Posted by quattrorunner

Freeze? Maybe in the winter.

I have headers so no heat, NP in so. Fla, BUT my feet froze during a trip to north FL .

I replaced everything except the front cond and its blower. Good kit, good quality, straight forward, no probs, I recommended to them a 90 degree instead of a 45 at the evap connection, but it was workable. I wish it had a real Sanden not a knock off.

In another trip to north Fl in Apr, maybe low 80s outside and sunny, but not the brutal summertime temps, with two in the car. we had to turn the tsat all the way to the left cause it got so cold inside. This was on the turnpike at 3200 rpm. I don`t use the car in rush hr traffic, stop and go in the middle of the day, so I cant say what it`ll be like. I think it will be OK once its cooled the inside.
It`s still the original a/c design but with modern components, and claimed 30% more airflow...thats why I bouight it.
Observations:
Drivers side vent blows hard, on the face,... good! Usu I close it off a bit. Other vents don`t get air to the drivers face. Not the kits fault though.
If anything I would increase the capacity of the front cond blower, perhaps the motor has slowed down (25 yrs old!) cause it doesn`t feel like much air is coming thru.

I also thought about a complete redesign but at the end it would prob just lower the value of the car. But yes, a blow thru evap, bigger blower, like double the CFM, and better condensing. This topic has been flogged to death IMO however.

[wwest]

Originally Posted by ganun

I have headers so no heat, NP in so. Fla, BUT my feet froze during a trip to north FL .

I replaced everything except the front cond and its blower. Good kit, good quality, straight forward, no probs, I recommended to them a 90 degree instead of a 45 at the evap connection, but it was workable. I wish it had a real Sanden not a knock off.

In another trip to north Fl in Apr, maybe low 80s outside and sunny, but not the brutal summertime temps, with two in the car. we had to turn the tsat all the way to the left cause it got so cold inside. This was on the turnpike at 3200 rpm. I don`t use the car in rush hr traffic, stop and go in the middle of the day, so I cant say what it`ll be like. I think it will be OK once its cooled the inside.
It`s still the original a/c design but with modern components, and claimed 30% more airflow...thats why I bouight it.
Observations:
Drivers side vent blows hard, on the face,... good! Usu I close it off a bit. Other vents don`t get air to the drivers face. Not the kits fault though.
If anything I would increase the capacity of the front cond blower, perhaps the motor has slowed down (25 yrs old!) cause it doesn`t feel like much air is coming thru.

I also thought about a complete redesign but at the end it would prob just lower the value of the car. But yes, a blow thru evap, bigger blower, like double the CFM, and better condensing. This topic has been flogged to death IMO however.

Even NEW, that front lip blower is pretty horribly inefficient, POWER IN, NOISE OUT, plus very little airflow.

I firmly believe that the factory system, even in the worse US climate environment, will product satisfactory airflow temperatures at a consistent 3500 RPM or above.

NOT saying that fully satisfies the overall human comfort equation. Radient heating (or "cooling) can be more than 50% of that equation. So it's possible for the cabin atmosphere to be in the somewhat discomforting range (<68F for me), and still be to "hot" for comfort.

[ganun]

Yep, ....my wife would be MELTING , and I would be FREEZING......hasn`t changed in 20 yrs. Amazing