Air Con recharge, what to consider?

[jsveb]

Hi

I have an AC in my 930, but it really doesn't blow as cold as it did 6 months ago. Back then it blew real cold - I figure it needs recharging.

This car is still somewhat new to me, and AC is not something I used to worry about back home (due to colder climate).

My question is: What do I need to consider as far as recharging the AC. Can I just by a can at i.e. Autozone and charge to system?

Or isn't it that simple.

thanks

[T77911S]

it is most likely R12. if it is, the only place you can get it is Ebay, but you still have to know how much to put in.
if it is not completly empty, buy some r12 and have someone charge it and see what is going on.
if it is empty, you may consider pulling the evap and cleaning it, along with the condensor(S) and replace the expasion valve. (and of course the dryer).

[Hugh R]

Buy a can or two of the R-12 replacement if it still has any juice still in it and see what happens, wear safety glasses!

[brads911sc]

Could be that simple... but not likely.

1. Are you sure that what is in there now is R134a? That is all you can buy at Autozone. If its R12 you cant buy it easily although you can get it on ebay.
2. You obviously have a leak somewhere. R134a is up 20% in the USA in the last year due to environmental concerns. It will likely double in price when the rest of the world outlaws it in 2012. What happened to R12 is going to happen to R134a. so you want to fix the leak.
3. If you have old components you likely will not be happy. What feels cold in October and March will NOT feel cold in June-September in AL or any other southern state.
4. AC is a slippery slope. Upgrading one piece makes it almost required to update other pieces. Example, one weak link is evap capacity. Once you fix this with a serpentine Evap, then you will find air volume is the issue, once you fix that with the Griffith high output fan you will find condensor volume is the weak link. once you fix that with new high capacity condensors you will find that it would make no sense not to change the hoses and compressor. Youll be in 3k before you have a modern system that will not leak and will make you sort of cool in the summer. Even with that level of upgrade, it will be no where near as cold in the rear seat area as a Honda or Chevrolet.
I opt not to drive mine between the hours of 12 noon and 4 pm. because even though i can be marginally comfortable, as soon as i park the car and it becomes 100 degrees inside.. there is NO way the system will be able to recover and actually cool the car.
5. Avoid the Hydrocarbon based refrigerants. The are not approved by the EPA. They will void ALL equipment warranties and you will find NO one who will touch your system for future repairs if you have used it.

Hope this helps.

[jsveb]

Wow, that was fast response.

As I said AC is unknown territory for me, but I do know the AC in my car is already severely upgraded. I think it has three evap.; on in the engine bay, one the front of the car and one underneith the car, the last one is huge.

I guess this just makes it even more expensive to repair.

I'll do some more studying and get back with more questions once I actually got the knowledge to ask them.

Thank you all

[T77911S]

those are condensors. one in the front, one on the rear tail. the one in the smugglers box is evaporator. they all need to be clean.

unless someone added a condensor.

[jsveb]

Condensers, OK. Makes sense, since they look like radiators and what ever is in there might condense once cooled???

It has got another BIG one under the car as well.

What can I use to detect leaks?

Thanks again

[rusnak]

He's got a belly pan condenser. If you can manage to post a pic of the compressor, tthen we'll know if you've got 134a. You need a high/low gauge set, and possibly a vaccum pump, depending on how much of a charge is in there.

[Gogar]

You can tell if it is R-12 or R-134 by the fittings on the compressor in the engine bay. Maybe take a pic of the compressor and post it here and that will help, too.

If it has been "upgraded", then that could be good news for you, because maybe someone else has already spent money on the big $$ items.

[wwest]

Originally Posted by jsveb

Hi

I have an AC in my 930, but it really doesn't blow as cold as it did 6 months ago. Back then it blew real cold - I figure it needs recharging.

This car is still somewhat new to me, and AC is not something I used to worry about back home (due to colder climate).

My question is: What do I need to consider as far as recharging the AC. Can I just by a can at i.e. Autozone and charge to system?

Or isn't it that simple.

thanks

I have long suspected that the biggest, maybe ONLY, problem with the earlier Porsche A/C systems is the lack of a high pressure limit switch. The only limit for compressor operation is the evaporator temperature sensor. So with a virtually infinite HP input to the compressor the refrigerant pressure could be, go, excessive long before the evaporator cools to <35 degrees.

So I would suggest doing two things, add the pressure switch, a modern one, and convert to R-134a. The newer pressure switches not only prevent the pressure from rising too high but also open the circuit if the refrigerant level is too low.

[brads911sc]

I have mine open so now would be a good time to add such a switch. Do you have a suggestion on brand/model of switch? vendor?

Thanks

Originally Posted by wwest

I have long suspected that the biggest, maybe ONLY, problem with the earlier Porsche A/C systems is the lack of a high pressure limit switch. The only limit for compressor operation is the evaporator temperature sensor. So with a virtually infinite HP input to the compressor the refrigerant pressure could be, go, excessive long before the evaporator cools to <35 degrees.

So I would suggest doing two things, add the pressure switch, a modern one, and convert to R-134a. The newer pressure switches not only prevent the pressure from rising too high but also open the circuit if the refrigerant level is too low.

[jsveb]

Here is a picture of the AC compressor.



I hope this can help you to determine what type?

[rusnak]

That's definitely an R-12 system, not 134a. I would get a set of R-12 gauges, and see how much pressure is still in there. It will be much better than a 134a converstion.

[brads911sc]

This might be a case where you take it in to an AC shop. 1st, you arent going to easily detect a leak on a system with lots of add on condensors. 2nd, You cant easily buy R12 anyway. You will spend north of $25 for one 12oz can on ebay. 3rd, a shop can evacuate, inject a die, and find the leak without letting any R12 into the atmosphere. If you are going to keep it R12, there are many reasons to pay the $100 or so they will charge to really check out this system. Otherwise you could piss away $100's of dollars worth of R12 finding and fixing your leak...

[RSTarga]

I agree, take it to a godd a/c shop and have it checked out. It probably just needs freon. I've heard those big underbody condensers do a good job.

[jsveb]

Hi guys

I gotta be honest and say that I have not been able to do justice to all the advice you have given me - yet.

But, today I opened up the engine lid again. I tried to unscrew the black cap on the RH "filler" plug on the AC compressor. It was moist, and it was as if I could see a small bubble as if the valve was leaking ever so slightly.

Is this valve just a valve, kind of like on a wheel? I am not considering a DIY swap with an air valve. I am just asking, and sharing my latest findings.

I have yet to find a local AC shop - that I'll trust to work on the car.

Thanks

[Neel]

Originally Posted by brads911sc

I have mine open so now would be a good time to add such a switch. Do you have a suggestion on brand/model of switch? vendor?

Thanks

Brad, there are 2 ways to go.. One, purchase a high pressure hose from Griffth with the switch in the hose.. Two, one I use a good bit is from Cooling Depot, part # 36683.. If your local parts house can't find it, I'll be happy to send you one at my cost + shipping.. Easy wire up, just splice it in series with the wire going to the compressor clutch.. I hope this helps...

[Neel]

Originally Posted by jsveb

Here is a picture of the AC compressor.



I hope this can help you to determine what type?

You have R-12, I've made these cool reasonably well with proper 'tweaking' of the charge..

[Neel]

Originally Posted by brads911sc

Could be that simple... but not likely.

1. Are you sure that what is in there now is R134a? That is all you can buy at Autozone. If its R12 you cant buy it easily although you can get it on ebay.
2. You obviously have a leak somewhere. R134a is up 20% in the USA in the last year due to environmental concerns. It will likely double in price when the rest of the world outlaws it in 2012. What happened to R12 is going to happen to R134a. so you want to fix the leak.
3. If you have old components you likely will not be happy. What feels cold in October and March will NOT feel cold in June-September in AL or any other southern state.
4. AC is a slippery slope. Upgrading one piece makes it almost required to update other pieces. Example, one weak link is evap capacity. Once you fix this with a serpentine Evap, then you will find air volume is the issue, once you fix that with the Griffith high output fan you will find condensor volume is the weak link. once you fix that with new high capacity condensors you will find that it would make no sense not to change the hoses and compressor. Youll be in 3k before you have a modern system that will not leak and will make you sort of cool in the summer. Even with that level of upgrade, it will be no where near as cold in the rear seat area as a Honda or Chevrolet.
I opt not to drive mine between the hours of 12 noon and 4 pm. because even though i can be marginally comfortable, as soon as i park the car and it becomes 100 degrees inside.. there is NO way the system will be able to recover and actually cool the car.
5. Avoid the Hydrocarbon based refrigerants. The are not approved by the EPA. They will void ALL equipment warranties and you will find NO one who will touch your system for future repairs if you have used it.

Hope this helps.

Brad, I agree with everthing you're saying, however I don't understand why your car won't freeze you out even in the middle of a TX summer, given your upgrades.. It gets hot and humid here in SC also and my A/C needs to be turned down even in mid-summer heat.. I have a complete Griffiths system in my car and it's black/black..
Follow Griff's evacuation and charge procedures (which I've used for years before reading his instructions). I have digital gauges, weigh in the charge from a 30# cylinder and have a vacuum pump that will suck the chrome off a trailer hitch.. It takes time.. Most techs aren't well versed in the proper procedures and/or don't want to take the time, or have the proper equipment to do these critical procedures properly..

[kuehl]

Jes,

Assuming your climate is like Montgomery, AL? 6 months ago the average temps were typically high 70's to low 80's? somewhat like April now? So possibly your system has lost refrigerant. There are few simple trouble shooting things you can do such as:
1) Determine if the compressor clutch is engaging, with the thermostat knob on max cold (fully clockwise) and the fan speed switch on, engine running, engine deck lid up, verify if the outer hub on the compressor pulley is turning along with the pulley.
If so then you know your system controls and compressor are working to a point.
2) You made a note that when you removed the black cap on the schrader valve port on the compressor you saw a bubble? Possibly your schrader valve inside is loose or leaking. You can use atypical bicycle valve tool to try to tighten the valve inside (gently, don't over tighten, its not a spark plug). You would not want to remove the valve core inside if there is refrigerant in the system.
3) Sounds like you have Nippondenso compressor (rotary piston), a deck lid condenser under the RH side of the engine lid, a belly-pan or "Armadillo Killer" under the tub and a front condenser. Depending upon the color of your car, the climate, number of occupants, etc. this condenser arrangement may just work for you.
4) Since you have stock service ports on the compressor you could assume the system is using R12, unless someone put in some other type of refrigerant and did not install the normal service port adapters. Normally when a car's refrigerant is changed there should be a sticker in the engine compartment which tells you the type of refrigerant, qty and type of refrigerant oil,.... this is only found if the car is "properly" documented. So for the moment you can 'assume' it is R12 refrigerant.
5) Unless you are ready to invest time and dollars in servicing the refrigerant system yourself I would suggest you take it to repair shop by you, a shop that
deals in Porsche's is preferred however you can go to any repair facility that has refrigerant evacuation, charging and test equipment to have your car checked.
They would attach their service gauges to see what the pressures are.
From there they can tell you if things look normal. If not you can ask them to quote you the cost to evacuate, charge and test system, and ask them if they can check all the components for leaks using an electronic leak detector (hose joints, compressor nose seal, compressor service ports, fittings at the condensers, drier and evaporator, and sniff the vents). From there they would give you an "estimate" to repair and you can make a decision from there.

Keep us posted,

Griff