Griffith's fender condenser dimensions

[scottb]

Bill: I initially had the same reaction as Charlie, but I didn't post it. $140 is cheap to recover your R12 and then later evacuate and recharge the system. If the job is done properly, that seems like a VERY reasonable price (even using your recovered R12). My local a/c shop doesn't charge to recover the R12, but they only give me 50% credit for it when recharging the system. My guess is your local shop may be doing the same. Still, $140 is pretty reasonable.

[brcorp]

I guess, but then there is the issue of unknown paws on my car. Plus I'm being cheap, i.e. the reason I started this thread which btw has over 11000 hits

[rusnak]

Where do you guys get your R12? Can I buy it in a huge cannister and service an R12 system at home? I have all of the 134a stuff, and have gotten good at keeping it running. What is the full charge operating pressure of an R12 system? How do I flush the 134a out, and where do I get the oil for an R12 system?

[brcorp]

You have to have a license to buy R-12, easy to get though. Sure you can buy a canister - costs $$ though.

Mineral spirit flush the entire system except expansion valve, dryer and compressor. Just let the compressor drain out fill and flush and fill with the correct oil.

[kuehl]

Originally posted by rusnak
What is the full charge operating pressure of an R12 system? How do I flush the 134a out, and where do I get the oil for an R12 system?

The full charge pressure (high side) varies with the ambient (outside air temperature). You can look an R12 "P&T chart" which shows what the average high side pressure should be at a given ambient.

You don't have to "flush" out R134a. You evacuate it out.

If you were running R134a before with "ester" oil (and not PAG), you can simply use the ester for the R12 application as well. However if you are a purest, then you would use AC "mineral" oil for the R12 and you maybe able to get some from a local autoparts store (though not a big moving product) or ask a local ac shop to sell you a small portion.

[niner11]

I promise to post pics when I get this thing working but for now I'm having problems with getting the car to take a charge of 134. This is part of the project to mount a 964 condensor and a procooler.

The basics: 82 911 rotary compressor, procooler, front fender 964 condensor. I just put vacuum on the system for over 45mins and proceeded to add 134 to the low side. Deck lid closed and high idle but after about 14 to 16 ozs it stopped taking refrigerant. Pressures were about 35low and 180 high at 80 f. Thanks for any ideas that you guys may have.

Chuck

[Jim Sims]

45 minutes evacuation time is on the "skinny side" for 80 F and your climate - three hours would have been far better to get the water out.

What makes you think it stopped taking refrigerant? At 80 F I would expect high side pressures of around 200 psi. What is your dash vent temperature? When it starts rising, stop adding refrigerant. The last portion of a charge is taken in much more slowly as there is less pressure differential to drive the flow of refrigerant out of the can. Be patient.

[niner11]

Thanks for the input. The can does not feel like its getting any lighter but I'll let everything cool down and try it in the am.

[fintstone]

Now that I have a bit more seat time with my new (feezing cold)A/C, I feel more capable of fairly addressing some of the earlier posted noise questions regarding the fans on the Dual Kuehl set-up. My '74 has SSIs and a stock 2 in/1 out muffler and a 3.0 engine. The fans on the Kuehl set-up are quieter than the factory fan on my Carrera oil cooler. In fact, I cannot hear the A/C fans over the engine from the inside of my targa with the top on or off. Although I do not have a CAT, the heat from the SSIs do not seem to have any effect. They sure seem like a great product to me.

[kuehl]

Originally posted by niner11
I'm having problems with getting the car to take a charge of 134. This is part of the project to mount a 964 condensor and a procooler. I just put vacuum on the system for over 45mins and proceeded to add 134 to the low side. Deck lid closed and high idle but after about 14 to 16 ozs it stopped taking refrigerant. Pressures were about 35low and 180 high at 80 f. Thanks for any ideas that you guys may have.
Chuck

Niner11,

Though I think the technique of charging the system has been addressed here and other threads, maybe this brief will clue you in on the system "taking on a charge". It is all relative to pressures.
The pressure in the refrigerant can must be greater than the pressure in the carls refrigerant system. Hence one reason why you have a vacuum on the car's ac system.

Assuming you have a good vacuum (45 minutes on a typical front engine car with all the ac components in the one area may be near adequate, however with atypical 911 with 3 times as much hose we find 3 hours to be more practical), on the car' system there are two methods to get the refrigerant from the can into the car.

The first is the more common method, what is called charging by gas. In this case your refrigerant can is upright (the exit point for the refrigerant is at the top). Your refrigerant can's hose or the service gauge set is setup to put refrigerant gas through both the low side (blue hose) and high side (red hose) of your service gauge set into car's system. The car engine is off so the compressor will not turn. After the car's system has taken in as much refrigerant as it is capable of, meaning the pressure in the car's system is the same as the pressure in the refrigerant can. You then close off the valve on the refrigerant can, close off the valves on your service gauges and close off the service valves attached to the car's refrigerant system. You note or determine how much refrigerant you have allowed go into the car, such as when you are using a 30 lb can of refrigerant you should be using an electronic weighted charge scale. If you are using small 12 or 16 ounce cans of refrigerant you have to wing it perse. You start the car's engine and turn on the ac system to full max. You then open the low side service valve on the cars refrigerant system, open the valve on refrigerant can, and then open the low side valve on the service gauge set. You monitor the amount of additional refrigerant gas until you have put in the amount of refrigerant you wish (another topic; we wont' address charging by pressures and temperatures for this post). If the refrigerant will no longer flow from the refrigerant can into the car's system you can either, increase the rpm's on the engine which typically lowers the low side pressure on the car's system, warm up the refrigerant can in a bucket of hot water, or use an electrical heat blanket designed for ac refrigerant cans, or use a metered heated refrigerant flask.

The second method of charging is called charging by liquid. In this case your refrigerant can is inverted (the exit point for the refrigerant is at the bottom). All the hoses are connected as noted in the first method, however the low side valves at the compressor and at the your service gauge set are turned off. The engine in the car is off. Your refrigerant path will be through the high side of the vehicles system; high side valves open, low side valves closed. You never charge by liquid through the low side as you can either flush the oil out of the compressor (leading to premature wear) or damage the reed valves in the compressor (called slugging). The liquid method is usually much faster than the gas method however with speed comes caution. You much have a very good idea as to how much refrigerant you wish to inject this way. Though, you can always get near say 80% of your target value and then switch over to the gas method to fine tune the final charge amount.

One little fluke to be aware of when using any brand service gauge set is that the rubber bushing seal located in the end of each hose fitting (which does not have a one way valve) tends to compress and close off the opening if you overtighten the service set hose fittings. This slows down both charging and evacuation procedures.

In other regards to service gauge sets, I purchased inexpensive and expensive brands and have had problems with loose needles on the gauges and leaks in site glasses. So know your equipment.

Be aware that it is very easy to forget which gauge valves or vehicle system service valves open or closed. Such as when you go to check the car's system running pressure you never want an open path from the cars high side going back to the refrigerant can. It is very easy to be careless or forgetful. So visualize the procedure, walk through the steps and don't try to take shortcuts. Otherwise it is a very simple procedure if you know what is going on around you.

You may have read in a few posts about pulling a 3 hour evacuation as opposed to one half hour to 45 mins. Personally I find that 3 hours works very well considering the length or capacity of the system. Whether you are using the 1/2 hour, 45 min. or preferred 3 hour evacuation. You might want to be aware of two hidden obstacles that can arise during the evacuation process that can leave even the experts puzzled when it comes time to testing the system.

The first obstacle or phenomena, we shall tag it for the moment, is where moisture or water should have boiled out under vacuum however it still present even though in theory you have lowered the boiling point of water by pulling a vacuum. We had a few clients, and we stumbled upon this problem once here, who pulled more than adequate vacuums on their systems however "internal icing" symptoms occurred. . What we mean by internal icing is that moisture still present in the system will cause problems at the expansion valve or in the drier.

A local friend does a lot of ac work on commercial (freezer boxes, buildings, residential) units and he suggested the following problem could be occurring: "If by chance you are pulling a vacuum and for some reason your vacuum pressure drops significantly and quickly in a long system (long as in the term so linear feet) before the moisture has had chance to boil off, the moisture will freeze while under vacuum and remain there ( I won't go into the related science of this as this is a one cup of coffee morning, but take it for what it is for the moment). So though you feel you have pulled down the vacuum level to or below the point where water will boil and evacuate from the system, what happens is the system actually freezes and hence remains there. One method to remove this remaining moisture is to do one of the following: a) after pulling a vacuum you flush the system with an inert gas, such as nitrogen (a bottle of nitrogen and an adapter with hose are relatively inexpensive in consideration of the time you waste troubleshooting the problem). So you pull a vacuum, allow the system to rise to atmosphere, blow in nitrogren, and then pull another vacuum. The dry nitrogen will help push out the air and moisture. Or b) simply use refrigerant in place of the nitrogen. I won't go into the how's, why not's and how much is acceptable in terms of purge refrigerant under the EPA guidelines however let's just say it can be done with respect to using refrigerant if you don't have nitrogen handy.

So getting back to evacuating the system consider splitting the process/procedure into two sequences. For example, after pulling a vacuum for 1 hour, you then proceed with the typical "gauge lock" where turn off the vacuum pump, close off your service gauges and check for gross leaks. If no leaks are apparent you then slowly open the system and allow it rise to atmosphere and inject dry nitrogen or refrigerant into the system, and then evacuate out the mixture from the system, and run the vacuum pump for two hours.

The second obstacle is more common in vehicles that being converted from R12 to another refrigerant for the first time. This problem relates to residual R12 trapped in a system that appears to have been properly evacuated (under negative pressure); you don't know it is there.
You then continue with an evacuation process and then inject our alternative refrigerant (R134a or whatever). When you test the system's pressures the high side is way off the earth and totally erratic. This problem relates to residual refrigerant trapped in the cars a/c system oil and or the desiccant in the drier. I have run across this problem years back when we first started exploring ac systems. After evacuating the old refrigerant from the system and noting a negative or minus gauge reading, when I opened the hose fittings to remove the drier suddenly liquid refrigerant spews out of no where. Here, even though we evacuated the refrigerant from the system, we have a negative reading on both sides of the system, refrigerant is trapped in the drier. Whether this problem is related to an ice block in the system as previously discussed or truly dormant refrigerant trapped in the ac oil or desiccant, we will never know. However we have avoided this on all subsequent evacuations by either using nitrogen or charging the system twice with refrigerant.

With respect to how much refrigerant you might be targeting on your setup, assuming you are only using the single 964/993 front condenser setup I would guess you would in the neighborhood of 29 ounces of R134a, or what atypical 964 or 993 would use; again it is a guess the 964/993 use a larger evaporator and the hose volumes are different than the 911.

Keep us posted.

Kuehl, totally chilled on this lovely Sunday afternoon.
Becks nearby.

[niner11]

First off thanks for the information and the great write up that you posted.

My SC has been running on 134 for a few years with a rotary compressor and a new receiver dryer and done a reasonably good job of cooling the car. For one reason or another this spring it would cool well for a few minutes then almost nothing. Mostly I needed a reason to install the procooler and 964 condensor, so here we go. The factory condensors are still on the car I just added the later model one in the front left fender (with no permanent body mods)

I ran a #6 from the front factory condensor into the 964 condensor's smaller inlet and a #8 out of the larger outlet. The #8 then was spliced into a #6 that returns to the procooler. To me it looks like the procooler is mostly a refrigerated reciever dryer.

I have confirmed with the previous shop that the system is using PAG oil so I measured roughly what came out when I opened it up and guestimated that and additional 5ozs would be safe to put back in. I have additional hose length and the add on condensor to consider. Any advice would be great.

[niner11]

(continued)

The best that I can figure right now is that I have about 30ozs in the a/c system but these small cans are hard for me to judge. Any thoughts on the amount of 134 in the system would be much appreciated. Procooler instructions recoment 25 to 28 oz but that is assuming a stock setup.

I'll post a better write up when the whole thing is up and running but I did not have much trouble mounting the 964 condensor in the fender. True it does not have the factory housing but it is reasonably well protected and it uses an aftermarket fan for cooling.

One more question: I have heard that you can check for blockadge in an a/c system by feeling the inlet line and outlet very close to the condensor. If there is an extrem difference then the blockadge is somewhere upstream of the cold line. Any truth to that? Thanks again. Chuck

[kuehl]

Originally posted by niner11
I ran a #6 from the front factory condensor into the 964 condensor's smaller inlet and a #8 out of the larger outlet. The #8 then was spliced into a #6 that returns to the procooler. Any advice would be great.

Go back and visit the connections at the 964 condenser in terms of what goes in and what comes out. A #8 is on the 964/993 condenser is usually the gas side and the #6 is usually the liquid side. So in a 964/993 you pump from the compressor (or from one of your other condensers) into the 8 larger opening (gas) and it leaves the 6 smaller opening (liquid). I don't know if I read your post correctly but it sounded like you have to change your in's and out's at the 964 condenser.

[kuehl]

Originally posted by niner11
(continued)

The best that I can figure right now is that I have about 30ozs in the a/c system but these small cans are hard for me to judge. Any thoughts on the amount of 134 in the system would be much appreciated. Procooler instructions recoment 25 to 28 oz but that is assuming a stock setup.

I can't comment on the pro thing but the rule of thumb when converting from R12 to R134a is that the amount of refrigerant will be between 70-90% in weight of the original charge. So if you have 47 oz R12 system you can do the math and get a feeling as to how much refrigerant to start with (70%) and then adjust your final charge based on P&T's or pressures and temperatures. I know there is a fella in FL that uses alot of our Kuehl serpentine evaporators in stock 2 condenser systems and he swears that 30 ounces works perfectly ... which is almost 10% below the 70% rule of thumb.

One more question: I have heard that you can check for blockadge in an a/c system by feeling the inlet line and outlet very close to the condensor. If there is an extrem difference then the blockadge is somewhere upstream of the cold line. Any truth to that? Thanks again. Chuck

Well there are quite a few "tests" you can do on systems to see where blockage perse may be, you can hose water on condensers, check pressures up stream (if you have fittings installed), check temperature drops, feel the expansion valve, look for frosting where it should not be, on and on.

I think first I check the in's and out's on your 964 condenser. Then I'd pull a good vacuum as discussed.
Then borrow a 30 lb bottle of R134a, an electronic scale,
and start from there with the guidance of a pressures and temperatures chart. Any good data from the test day, such as ambient temperature, relative humidity, fan speeds, vent temps, low and high side pressures at idle are usually the baseline you use to start tweeking or fixing.

Gotta, go.
Test drive is in order on the new blower (engine).

[niner11]

Thankyou unfortunately you read it correctly. I do have it backwards coming from the front condensor into the 964 one. Good news is that I have the hose length and fittings to correct it but here we go again with evacuating and charging the system.

Dumb question maybe but will it make a big difference in performance and or head pressures?

[kuehl]

Originally posted by niner11
I do have it backwards coming from the front condensor into the 964 one. Good news is that I have the hose length and fittings to correct it but here we go again with evacuating and charging the system....... but will it make a big difference in performance and or head pressures?

Will it make a difference?
In theory yes, because you have a liquid line or narrow line feeding into a larger diameter line so "maybe" the liquid could expand to a gas again.

I think I posted a note about a scenario where when you are charging a vehicle system with the liquid method and if you have a constriction in your charging lines (you can't get the liquid into the system quickly) the refrigerant expands back to a gas after it has entered the vehicle side and the system pressures equalize too quickly making charging more difficult.

Remember that in "practice" most condenser designs start with the gas entering a larger diameter and the liquid exiting through a smaller diameter. The flow enters the the top side of the condenser and comes out the bottom.

Frankly I have never designed, tried or tested an ac circuit where gas enters a small diameter and exits a larger and I have never tested it first hand. So I can't tell you from my experience whether it could make difference. I could also relate to the idea in this light: "trying to supply 20 amps of 120v, down a given length, through a small 20 gauge wire when I know from practice I'm suppose to be using at least a larger 14 gauge wire".

So, in the mean time, you might as well follow the practice of the trade. Recover, evacuate with some new knowledge, charge and test.

[niner11]

It was simple enough to fix the a/c lines and an even better idea to evacuate the system for a much longer time. Thanks
Chuck

[E Ray]

I guess I will jump in here, I have been working up to putting the a/c back in the 930 for about 4 years now, I think it’s about time. My plan is go with a 3 condenser system, rear fender, static belly and the stock one up front, while loosing the factory rear unit. I already have some of the basic bits, a new compressor, receiver/dryer, expansion valve, new front condenser and a 993 condenser assembly.

My question is has anyone fit the 993 unit in the rear fender area? Pictures? In its stock configuration it will not, I think it will fit with some modification to the sheet metal. I would really like to see how anyone else has done this before I start cutting it up.

Eric

[niner11]

Any chance that you could post a few pics of the 993 condensor and or its measurements? I thought long and hard about just putting the big belly condensor on my car but I like the 964 or 993 install a little bit more.
Chuck

[E Ray]

I will try to snap a few pix and take a few measurements tonight.

Eric