Improved Front Condensor Performance!
 

I bet half of you who opened this post thought I had the answer...no such luck! I'm looking for the holy grail on front a/c condensor performance improvement. The question is.. Has anyone successfully improved the performance of their front mounted 911 a/c condensor? I've done a search and seen lots of info on people asking the question but what I haven't found is someone who has achieved success. Specifically looking for info on anyone who may have found a way to better duct air to the condensor, found a way to get the condensor in the airflow of a moving car, found a better fan, or found a way to successfully speed up the fan. I've come to the realization that I'm at the point of being "condensor challenged" and would like to exhaust all innovative ideas on the stock condensor before I start spending more money on new replacement condensors. I have to believe that someone out there has figured out how to get more airflow to the condensor in it's stock or nearly stock location? Even if I eventually spring for one of the new serpentine front condensors I'm sure it would benefit from better airflow than the stock setup.

It's 93 degrees today and 74 percent humidity......

Help!

Not much you can do to that condenser. Try adding fans to the engine condenser or add a condenser in the driver side wheel well with a fan or underbelly condenser from Performance Air. Switch to ES-12a, add a subcooler (procooler). By the improved fan for your evaporator from www.mrjaguar.com. All will get you improvements. Try a search on es-12a or procooler. Many are getting high 30's from the vent.

I plan on doing the high effeciency evaporater

http://www.rennaire.com/index-2.html

with the Kuel front condensor
http://www.griffiths.com/porsche/ac/911ac/index.html#Condensers

All good stuff. Another option:

http://retroair.com/

Retroair is located near me, so I wound up using their products for an upgrade I did to my 930. It turned out very well.

Thanks guys...all good information but before this thread becomes a testimonial for all the various good products out there I'd like to keep the discussion focused on improving airflow across the front condensor. There has to be some method of getting more airflow across that front condensor whether it be through better ducting, a better fan, possibly a small scoop fabricated to grab air just below the condensor, possibly notching the underside of the bumper where the condensor fan intake is, etc. That's the kind of stuff I'm looking for...specifically guys who have experimented and gotten results. I'm pretty sure there are gains to be had here and I just was hoping that others had already done the experimentation and found what works.

Thanks again for the suggestions.

Do a Jim Sims subcooler instead of a procooler. If your making a/c lines it makes sense, $30 or $40 versus $300. I'm getting mid-30s on a 100 degree LA day on 134a

Focusing on your original query, I agree, Motorhead. I think the front condenser blower is not terribly efficient. I've also thought this area would be a good place to pick up some low-cost, improved performance. There were a couple past threads where guys were talking about using a marine bilge (is that redundant?) blower instead of the stock front condenser blower.

Another thread as I recall involved a guy who installed a second front condenser with computer fans blowing air over them in lieu of using a stock blower or blowers.

I'd like to see more cheap R&D applied to the front condenser/blower unit. It's the last shot before the evaporator.

Keeping it cool in Northern Virginia ...

Brian

People have been trying to cheaply modify the clunky 911 AC system for years.....and failing. Replcing old inefficient parts is the only way.

My 78 had factory air but was shipped without the front condenser. I have been slowly collecting parts so that when I re-install the A/C I have the option of installing the front condenser. Anyway, while searching the 78-83 PET for a list of parts I noticed that Porsche used a big honkin' fan assembly for the front condenser on some models [turbo, I think]. I don't have the PET with me but if you poke around you will see that they used a blower that appears to be the same as the rear heater blower. Not sure if it moved more air but it looks like it did.
I've wondered if more ducting and a pair of Spal fans would be more efficent at forcing air over the condenser.

This is the factory condensor fan below. My car has this fan and it works. Close examination this afternoon looks like there is nowhere to go with a fan swap without getting shadetree which isn't something I want to do. I may go ahead and notch the underside of the bumper to aid with airflow to the fan intake at speed (similiar to what other do to aid with oilcooler airflow). It's a no-cost out of sight mod.

While talking to a friend today who has a supercharged intercooled C5 Vette which is cooling challenged, he showed me his "Big Mouth" which is a stainless duct that routes air from below the front lip of his spoiler up into the intercooler which is mounted in a similar fashion to the Porsche condensor. He said it helps quite a bit with temps in the intercooler. Taking this idea I think I'm going to build a cardboard template and my bud has offered to fab up a ?little? Big Mouth for my Porsche. I'll also experiment with trying to shim the condensor down at the back a bit to maximize airflow across the surfaces. More to follow!

Also decided to opt for the Rennaire new "Desert Duty" Front Condensor to help things along. Ordered it today.

More to follow!

http://forums.pelicanparts.com/uploa...1152660813.jpg

Mororhead-45, What did you end up doing here? At last report you were going to change out your front ncondenser and do some experimental ductwork.

I was considering modifying the condenser coverplate to install one or two 4" spal fans blowing downward but there is no way to attempt without permanently removing the spare tire and I'm not ready to do that right now.

I sold the car last month to a guy in Atlanta but last summer I did a complete Rennaire upgrade to include one of the Rennaire Desert Duty front condensors and was "satisfied" with the results without further work. I'm on the Gulf Coast where we get both high temps and high humidity. The car was also a Targa which really tranferred heat from the sun into the cockpit during the day at work. About $1500.00 in parts and a weekend for the install but it worked well.

On my 82SC original A/C did not work properly from the day one that is last 24 Years since this was my Sunday morning car and we lived in N.J, A/C was not that important, now that i live in Eastern N.C, I needed the A/C.
Last year i took the whole system out, I got a new Sanden Compressor, New Barrier hoses and fittings, new Dryer/Receiver, new Expansion valve , new O-Rings and flushed the front and rear Condensers plus the Evaporator with a product called Clean and Flush. I put the system together and pulled 29.9 in Hg vacuum twice (i live at about the sea level), the third time i left the system under vacuum all-night to make sure there were no leaks under vacuum (a pressure test would have been more assuring but i did not do it). I put 2 onces of PAG-100 oil into the Compressor and divided 2 more onces between Dryer and the Condensers. Charged the system with 24 onces of R134A. Since then i have been getting low to mid 30's out of the vents here in N.C summer. Besides the Barrier hoses, Dryer, Expansion valve and Compressor rest of the system is all stock.
So i do not know if any after market equipment is necessary, Summertime here in Eastern N.C we may have weeks at a time above 90 F weather.
FWIW this is my A/C story.

Cheers

Here's a pic of the OE front condensor from my '86 next to Rennaire's desert duty. It is substanitially improved (not to mention cleaner) and I believe is available without buying the entire kit.http://forums.pelicanparts.com/uploa...1176248803.jpg

Rennaire is now selling their wares thru Pelican...the Desert Duty condensor is available here for $249.00 by itself.

Sure is pretty, might need to get me one! Looks deeper that the OEM - is it?

Only my front condenser and evaporator are original, everything else has been replaced. Got to think these modern units are much more efficient.

Keeping my fingers crossed...recent condenser fan adds are getting me very low vent temps (e.g. sub 30's). Now waiting for 90+ temps just around the corner for the true test. If my temps don't hold up, evap and front condenser are next.

Last summer (my first with a 911 daily driver) was the longest 5 years of my life - I'm determined not to sweat my a$$ off again!

The Desert Duty is twice as thick as the original.

[QUOTE]Originally posted by mthomas58
[B]Sure is pretty, might need to get me one! Looks deeper that the OEM - is it?

Yup, almost twice as thick. It's also serpentine which is more efficient than fin & tube. It takes a little work to bolt it up & it hangs a tad below the guard so it's a bit more exposed.

Another simple enhancement that is often ignored is to simply increase the idle speed a bit for summer operations. You'll get more airflow across the rear condensor and raise the compressor speed at the same time. This also helps with the typical slight loss of RPM at idle from the increased drag of the compressor. This makes a difference, especially if you spend much time in traffic. During the summer I ran my idle at 950-1000rpm and then backed it back down in the fall.

How about the "rubbermaid trick" set up on your condenser? Would that work?

???? What is that ????

I added 2 electric radiator cooling fans, ~$50/Ebay, to provide more consistent airflow downward through the engine lid condensor (and the engine). They run in series with the A/C system on and in parallel when the compressor clutch is engaged.

Removed the fuse from the front blower.

Thinking of shipping it off to my nephew in the Memphis area to confront the many naysayers "here".

'88 Carrera.

Old post but I'm working on something for this so I'll play along. MY 86 is all original and works, just not very well. I'm seeing 55* vent temps with ambient in the high 90s. I've been looking at ways to imporve performance incrementally without breaking the bank.

Recently discovered my front condenser blower motor seized. No fuse and I said a small prayer that it hadn't caught fire. Original plan was to replace the motor but the squirrel cage came apart on me as well.

I have a replacement unit coming from a fellow Pelican, but I figure I'll play around with the housing I have and see what can be done. Searching here it looks like the footwell blower motor is the same size and will fit in the con/blower housing but supposedly spins faster(more air flow).

I found a Fasco squirrel cage that is a little larger in diameter than the eom unit but looks like it will fit. Width wise it's good. I scored a pair of footwell blowers from eBay so I'll try that motor with the new cage.

There is also a thread here(sorry my links are on another compter) where a member sliced the motor area off the housing and bolted up a generic DC motor. Been scouring the internet for a suitable replacement motor but haven't found one cheap.

I'm about to head out for family vacatoin for two weeks. Should have stacks of parts waiting when I return. If I get anywhere with this I"ll post up again.

J

Front condenser...........
 

I have a front valence with the opening for an oil cooler. Since I have a large Setrab cooler mounted in the right front fender, the need for a front mounted oil cooler is non existant. I have thought of moving my front condenser to the spot where a front oil cooler normally lives and add a couple of small fans behind it. Haven't done it yet, but that's the plan.

http://forums.pelicanparts.com/uploa...1341921687.jpg

I replaced just the motor in the front condenser blower with a footwell blower motor - trade over the squirrel cage (rebalance if needed, bit of patience) and I think some minor mods to the electrical connections (I forget if it was a polarity or terminal-style issue, either way I don't remember anything dramatic was required) - otherwise mechanically it's identical...

Why bother?

'cos the footwell motors run at higher rpm than the condenser motors.

Noticeably louder but definitely made a difference. I'd already added a double-thick front condenser 10 years ago, although I'm sure the newer designs work even better, and converted to R-134a and added a trinary switch to compressor port to protect the installation, especially useful until I'd finished replacing all old leaky old hoses. Also added a foam seal around the top perimeter of the front condenser to force more fan/ram air to flow through it, not sure how much difference it made but seemed like a good idea at the time.

At center-console vents & home-made lower straight vent (where butterfly used to go), temps down to mid-low 30's on high fan speed in low 90's ambient here in SoCal. Just gone to a 3.6 so not reinstalling a compressor until I've got the oil cooling where it needs to be, but BAC the newer evaporators are a good way to go too re overall A/C performance, plus I'll add a fan to the engine lid condenser via the trinary.

I tried several things such as series/parallel stacks of electronics cooling fans and surplus squirrel cage blowers, but never found anything alternative that either had more cfm than OEM or would fit the space. Maybe those "electric turbo"/model aircraft/brake duct fans that install into SCAT, SKEET or other circular duct setups might work well for stuck-in-traffic, need a big relay though!

Never tried the "Rubbermaid" idea but would probably help in lower humidity areas. Not very convenient though to have to carry all that deuterium water in the luggage compartment for a daily driver though, plus swamp cooling the condenser not very p-car like... sort of same ilk as the window-mounted ice-bucket "mommy coolers" old-timers have told me you could rent at gas stations in the Dark Ages - but wait, there's an idea - probably more effective than stock pre wet 911 A/C :)

Can you tell me more about the fans you added in the rear? Do you have photos of the install?

Lol

yeah, I know, Brad, it sounds like a Wile Coyote thing or worse!

I am all for creativity. But what works in the Pacific Northwest with 74-81 degree July ambients, will NOT work in Florida or anywhere on the gulf coast with 90-96 degree ambients and high humidity.

Its silly for WWEST to even present that as a viable option in any location where the average daily ambients in June - September is 90-96 degrees when his mid July mid afternoon temps are 74-81 degrees.

After doing a complete AC upgrade on my 80SC the only piece missing was improving the front condensor fan. I replaced the old slow condensor fan motor with a stock main fresh air blower motor. More RPMs. Lots more CFM and fit the stock housing and squirrel cage like a glove! Don't forget an inline fuse for safties sake!

Great Idea.

Do you have the Part Number for what you ordered?

[QUOTE=fred cook;6848746]I have a front valence with the opening for an oil cooler. Since I have a large Setrab cooler mounted in the right front fender, the need for a front mounted oil cooler is non existant. I have thought of moving my front condenser to the spot where a front oil cooler normally lives and add a couple of small fans behind it. Haven't done it yet, but that's the plan.



http://forums.pelicanparts.com/uploa...1342046760.jpg

You mean like this? Yes it works, once moving it really cools very well. I've been thinking of going to a more modern serpentine from griffiths here but I don't know if it will fit.

I don't have a part number but I know our host has them in the catalog. I just disassembled an old fresh air blower assembly I had on the shelf. Pulled the motor out and took off the blower cage. Same with the front blower assembly. Hardest part was separating the front cage off the motor shaft. Tested both motors side by side to confirm that there was indeed a difference in RPMs between the motors.

A few more cents: I have read somewhere in these forums that the footwell blower motors are exactly the same size as the front a/c condenser blower motor. They are supposed to have a higher rpm rate for better air flow, but are also a bit noisier- mostly noticed at stop/go city driving speeds. I have seen the footwell blower motors on ebay- new, for about $75 as I recall.

Tim

See my post 50 above, and 19 in an older thread where I'd first mentioned using footwell motors in condenser - "Anyone ever update their vent/AC system to 86+?".

Also correction that with the system on my 3.2, low 30's in 90's only on low fan speed - high yielded 40's.

Our host lists the fresh air blower motor w/squirrel cage, etc. - 911-571-320-32-M6. Just the motor, I had a number jotted down, Bosch R2031-12430.

For some $50 Dayton 3LCH7 can be adapted to replace the engine blower (I and many others have done this), condenser and footwell blowers, and probably the fresh-air blower too, some mods to housings. It runs at 2350rpm. In previous threads, no-one seemed to have any rpm data on the various blower motors, but since replacing the condenser motor, have procured a non-contact tachometer, so next time blower bits need work, I'll take some measurements.

At least one thread here has pics of some creative rear condenser fan installs and mention that this helps in traffic/high heat, but I don't understand why one wouldn't keep the front condenser fan as well, FME anything you do to improve that component & airflow through it is worthwhile and conversely, disconnecting it cannot possibly be a good thing (unless it's about to catch fire :)
Barry

At this moment I am in Missouli MT having driven ~ 500 miles yesterday to get here. OAT was hovering around/above 95F from mid-WA to here, 2 or 3 slow-stop and go construction zones on the MT side. Otherwise speed was kept above 75MPH.

Only problem was the evaporator frooze up coming over the pass.

Even with the blower on low we had to lower windows slightly so as to not be too cold.

Car is Diamond Blue with matching grey interior and windows are tinted to the level WA allows. Once the interior is cooled it pretty much stays that way.

Not Huston or Memphis but climate wise closer than Seattle.

Cant prove it but Id think the front condenser is more a weakness than the deck. Not saying every bit doesnt help. Just saying that this will only work if everything else is great.

wwest, I'm curious as to your engine temps during these cooling periods - does your engine run particularly cool even with A/C on in slow/stop conditions in 90's?

For comparison, my India Red car would also get downright chilly on the freeway (I could run at low fan speed &/or lower the temp control and maintain); if I was stopped for long in traffic, I could keep cool but only at expense of 240-250F engine temp (approaching/on mark above 9-0'clock). If I parked in sun and car got hot, it might take 15-20 minutes on freeway for A/C to start to actually get car cooled off inside, longer around town.

My guess is color might be a big part too - mine's red, your very light and "bluetiful" color has to help over, say, a black car...

But still, how come you disconnected the front fan? Don't you think it would cool even better with that too? You can always lower the temp control and let the compressor cycle, course you might need to add a manual switch on your decklid fans...
Barry

Barry

J,
The technique for installing a Dayton Dayton 3LCH7 (about $50) into a footwell blower assembly is described here: (EASY DIY Footwell blower upgrade! - Rennlist Discussion Forums). It maybe be here too somewhere.

The technique would be similar for the condenser. I'm not sure though how the 2350rpm compares to the OEM footwell/condenser/fresh air blower motor speeds, which are all the same physical form (not sure about polarity) and are mechanically interchangeable (as per post 35) in those housings, FME footwell is faster than condenser motor and improves condenser. 3LCH7 is more usually used replace the engine compartment blower... but don't know rpm of OEM there either :(
Barry

Barry, will the Dayton motor shaft fit onto the cage fan of the front condenser without modification?