redidrum

Anyone got any ideas on how I can get my Air Conditioning to get colder? I've had the Freon serviced and checked for leaks. It blows semi cold air, but, not cold enough for me. It doesn't leak any freon and the fan blows strong. Just not anywhere as cold as my Toyota 4Runner. It is going to be a very hot summer here. I'd hate to park the car for the summer. I've heard of doing a rotary Compressor upgrade. Trying to make what I have work best. Everything works.

Please help?

Thanks,

Ron

H. Miller

Can't help you with the cold part. My 83 SC blows pretty cold, the problem is those small vents and the volume of air coming through them. Even if you get the air to an acceptable cold, you can't blow enough of it into the cabin to cool it (especially after the car has sat in the sun).
911 AC has a bad reputation.

DGaunt

An upgrade form the york 1-lung compressor to a rotarty will help. Also, someone sells auxillary vents for the SC. No question the lack of outlets hurts the A/C

On my '76 with under dash air, I went to a rotary compressor, upgraded to R134 (which hurts you a bit for cooling, but saves your pocket book) and put a can of Wurth sealer into the system. It is plenty cool now, even in 90+ high humidity days. The only time it is a bit inadewquate is when idleing in stop and go traffic. Of course if cost is no object, several companies will sell you complete kits that will work fine, but big $$$$$. Good luck. Sure takes the fun out of it when it's hot dunnit?

2002M3Drew

911's are notorious for bad AC until the 89 models. From what everyone says, semi-cold air is about all you'll get, and it's nowhere near modern AC standards even when working perfectly. I'm planning to actually remove mine completely to save weight.

You may want to try that Kuehl Vent that they advertise in all of the Pcar publications. Supposedly it rechannels air better and improeves the system performance.

wwest

Before you install a new compressor be sure the one you have isn't cycling off part of the time.

The early systems regulate the base, coldest airflow by keeping the A/C evaporator just slightly above freezing. If the A/C evaporator gets close to 33F then the compressor will be cycled off until the liquid refrigerant is exhausted, or the evaporator temperature rises significantly. A second control source prevents the compressor form supplying too high pressure in the system.

You might want to have a technician more precisely locate the evaporator's temperature sensing bulb such that at your coldest setting the evaporator surface temperature declines to ~33F but no lower.

Bottom line is that if your compressor is running continuously then its quite possible that a high volume compressor will help. If it cycles on and off as the control system demands it's already providing as much refrigeration as the system can, will use.

Amazingly sometimes a lower blower speed will provide a more comfortable level of cooling. At lower blower speeds the airflow takes longer to pass through the A/C evaporator core and is therefore cooled to a lower level. Think of two glasses of warm milk, one left in a 42F refrigerator for 5 minutes the other for 10.

Also remember that you do not have a recirculate mode. The higher speed the blower is the faster the "cooled" cabin atmosphere exhausts into the great beyond.

Duct tape over the exhauster vents..........???

JackOlsen

Aside from making sure the compressor is performing adequately (or upgrading to a rotary type), and making sure all the other components (hoses, dryer, accumulator) are working correctly, the biggest improvement will come from increasing condenser area. The biggest step you can take in this arena is the Performance Aire underbelly condenser, which puts a huge static condenser behind the front wheels on the belly pan. It's not an ordinary condenser, though. It's much stronger -- you can literally jack the car up on it.

Read more here. Rennaire and Griffiths also have good information on their sites.

wwest

The secret is to find the "weakest link", the component in the system that's bottle-necking the cooling performance. Adding a new condensor or compressor to a system that simply needs the cappilary sensor "calibrated" would make very little sense.

I often see where some owners are adding the third radiator to their 996's. To what purpose?

If, when the engine water jacket coolant thermostat opens to flow, full flow, and the existing two radiators are not sufficient for enough cooling to keep the engine within its operational parameters then fine, the installation of the third radiator is fully warrented.

The first test is to discover if the A/C compressor is cycling on and off in a benign, cool, environment and then in the most adverse, HOT, environment you can test it in. If it cycles off on something of a regular basis then you know that either the A/C evaporator core temperature is close to freezing or there is so much liquid refrigerant in "reserve" that the system pressure is too high.

If the compressor cycles on and off in the cool environment but runs continously in the hot environment then you need to look at a component upgrade.

If your vehicle happens to have the second condensor under the front nose of the vehicle then check to make sure the blower motor for that condensor, a VERY common failure, is fully operational.

redidrum

Okay, Thanks guys. I'm getting some knowledge here. I'll go for the exhauster vents, cheap fix, first. Where are they located? Are there any other places I could check for obvious leaks? I do notice the compressor turning on and off with the switch, but, not as the control system demands. It runs continuously. Should the round **** be to the left or right for the coolest air? It's Hot Here !!!!

Thanks, Ron

Bill Gregory

If you haven't already, you may want to view the 911SC FAQ on tech.rennlist.com, where A/C improvements are discussed.

DGaunt

I am not sure what Wwext is referring too re: recirculate mode. IF (and only if) the SC system is similar to my "OE" under dash system, the air is pulled from under the passenger floor board, through the evaporator (in the smuggler's cubby) and back into the cabin via the ducting. This is a recirc system IMO.

I can only tell you what I found on my system and what worked. We get very hot and humid days up here in summer. The York 1-lung compressor is a known weakness in the system. Replacing mine made a big difference. Well, it turned the AC from useless at ambients over 75 Deg F to good. The only other thing I did that wasn't mentioned is that my high-side pressures were too high. The AC guy said the condensor was partitally plugged and used an agressive solvent to clean it. Quite a bit of brown sludge came out. This also made a big difference in the AC.

Now, with those improvements/maintenance done, I can run the fan on low, with the compressor cycling, once the cabin has coooed down initially.

Is it as good as GM AC? Not quite, but close. The big advantage I have is the under dash vents have much more area and volume than your SC system. The Kuel vent was the one I was thinking of.

The AC is as good or better than my Golf TDI, which is known for a slightly aneamic AC system, but adequate.

i agree with the others that it is a good idea to find the weak link, but I think most who have dealt with the York compressor will point to that first.

justkickenit

There was a thread about this on pelican. A guy was able to get 32 degree vent temps on an 83 degree day using the procooler setup. Her's the link with pics. http://forums.pelicanparts.com/show...threadid=211526. I believe the whole system was $1400.

nota_troll

I love Rennlist. It's almost telepathic! Just when I'm considering a Rennlisters 911 for a daily car I read this about the A/C which Houston's heat and humidity are quite intense.

I guess I'll need to get another 993.

redidrum

Pete and everyone,

How about if I buy the A/C Compressor Kit and Receiver/ Dryer from Pete's site and hope that solves the problem? https://www.allzim.com I could install it and have the guy that just serviced it do it again, waste of money again! It wouldn't hurt to have the rotary compressor. I know a guy that completely redoes the system for $1500. He could always use the compressor and receiver/ dryer if I need to go that direction. Trying to save a few bucks. Where does the receiver/ dryer live on the car?

Advice ???

Thanks,

Ron

Peter Zimmermann

Hi Ron: First, the sight that you mention isn't mine! The company that my shop found to be invaluable over the years is who Mr. Olsen mentioned, Performance Aire in Anaheim, CA. They have many ways of attacking the SC A/C problem, which is precisely what I'm struggling with here in Bakersfield, where it is over 100 frequently during the summer months. I sold my '80 Targa a few months back, and replaced it with an '02 325 BMW, just because of the A/C issue. All the points made on this thread reflect knowledge and experience. Yes, the vents (improved in 1986) are too small, but Performance Aire has created a larger outlet for the left/right vent under the dash, just forward of the console. It truly helps, but the A/C still won't keep up with 100 degree days. My '82 still has the York compressor, its clutch is making noise, and I'm about ready to pull the whole mess out and preserve the engine (let it run cooler without the rear condenser blocking the rear lid), rather than spending a lot of money on a rotary, and the required R-12, only to be disappointed with it. The first thing that you must do is measure your center dash nozzle temp, while driving. Everything is based on that, if it's only 45 degrees, or higher, you have problems. If it's low 30s, then Performance Aire's lower vent will help you. If you call Perf. Aire have your high & low pressures ready to give to them, perhaps they can advise you regarding a problem that your tech might not be aware of. I also have found that the SC will cool better on fan speed #2, than on #3. Performance Aire also has condenser solutions, such as the one mentioned, but I have little knowledge regarding how effective they are on cars with small outlet vents. Good luck with whatever you decide to do, it's an expensive problem that frequently leaves the car owner bummed out regarding the end result. If you do the fix have your tech inspect the back of your fan speed and temp switches (the wires can cook), as well as replace the system relay in the smugglers box.
Pete

redidrum

Thanks for the info.. I've decided to bring the car to my Porsche guy here in Indy, Bob Farmer, and have him do his mod.. He replaces the Compresser, Dryer, Hoses, and all related parts to 134. He guarantees the car to be very cold. Will be less expensive than me throwing parts at it and losing expensive r12 freon every time. Thanks to everyone. I'll pay to have it done right. He is a very reputable guy and I trust him. Plan on keeping the car. I'll print this thread and have him check the items everyone listed here.

Thanks to everyone that assisted here. I'm standing down on doing it myself.

Ron