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TnBlkC230WZ
07-06-2009, 03:09 PM
I'm finally getting the AC system charged and I hooked up the compressor wire. I expected the compressor to cycle on when I turned the system on, but it didn't. I have a trinary switch installed. There is no power at the compressor wire.

Will the compressor run before the system is charged or does it have to have refrigerant in it for the trinary switch will allow the compressor to come on?

Edit: I do have power going to the trinary switch, but power is not making it to the compressor

dhutton
07-06-2009, 03:38 PM
You have to charge the system. The switch will not apply power to the compressor if the pressure is too low or too high.

Some good info in here:

http://www.vintageair.com/DownloadsSection/MiscDocuments/ACBASICS(92806)-Inet.pdf

TnBlkC230WZ
07-06-2009, 03:46 PM
Thanks, I was hoping it was a low pressure issue. I just wanted to make sure it was working before I took it in to be charged.

TnBlkC230WZ
07-07-2009, 02:50 PM
I got it charged and it is blowing cold. The mechanic told me to lose the trinary switch and wire the fan to come on with the compressor. He said the AC will stay colder if I keep air moving across the condensor. The fan does cycle alot.

dhutton
07-07-2009, 03:17 PM
I got it charged and it is blowing cold. The mechanic told me to lose the trinary switch and wire the fan to come on with the compressor. He said the AC will stay colder if I keep air moving across the condensor. The fan does cycle alot.

Somehow it does not seem like a good idea to have your fans running while you are going down the highway. I would stick with the trinary switch, they are only cycling while you are idling. Once you are moving they should stay off.

TnBlkC230WZ
07-09-2009, 05:34 AM
Somehow it does not seem like a good idea to have your fans running while you are going down the highway. I would stick with the trinary switch, they are only cycling while you are idling. Once you are moving they should stay off.

80% of my driving is in traffic. With the Dakota Digital fan controller, it is very easy to switch between the two. If I don't see a difference with it to the compressor or plan a trip, I can put it back. I'm curious if it makes a difference it the air temp. Sitting at idle, it is definitely not as cold. I am running a small SD7 compressor.

Twentyover
07-11-2009, 01:10 PM
You're mechanic is an idiot.

The trinary has three functions, compressor control at low pressure, compressor control at high pressure and fan control at intermediate pressure.

A trinary's only reason for being is to increase fan speed or implement fan actuation at intermediate pressure to reduce that irritating fan noise on a luxo cruiser. The remaining two functions can be handled w/ a binary. Wire the clutch and A/C fan actuation through the switch- it will protet the compressor at both low pressures (low charge) and high pressures (usually blocked airflow over the condenser.)

The trinary may be wired to implement the fan at intermediate pressure- as dhutton indicates, there MAY be enough airflow at speed to not require the use of an engine cooling fan at these conditions.

parsonsj
07-11-2009, 01:25 PM
Your mechanic is wrong (just to pile on).

Use the trinary switch. What Greg said.

jp

TnBlkC230WZ
07-12-2009, 04:16 PM
I will leave it in then. A different question. The AC doesn't get cold when it gets above 93 or 94 degrees. It isn't very cold to start with. I am missing my door panels and back seat, but I thought it would be colder.

parsonsj
07-12-2009, 05:36 PM
I'd make sure you have a full charge. Do you have a thermometer? You need to measure the temp of the air coming out. Put your A/C at max, fan speed about 3/4. You should get air temps in the 30s or low 40s, depending on ambient.

jp

TnBlkC230WZ
07-12-2009, 09:10 PM
I'd make sure you have a full charge. Do you have a thermometer? You need to measure the temp of the air coming out. Put your A/C at max, fan speed about 3/4. You should get air temps in the 30s or low 40s, depending on ambient.

jp

I only have my hand, but it is now where near 40 degrees. Maybe 70 when the ambient is 93 - 95.

Twentyover
07-13-2009, 05:31 AM
You really need a thermometer. Also, the system needs to be evaluated at about 1500 rpm engine speed.

A refrigerant's boiling temp is very pressure dependent- at the evaporator suction pressure ranges, a 1 psi drop in suction pressure results in about a 1 degree change boiling temp. At idle, the compressor isn't turning fast enough to develop really good suction pressure.

That said, you need to determine if the evap is reaching it's potential, or whether you are re-introducing heat in the system. Park it in the shade, let the engine cool overnight (I'd suggest a garage if available) wait until the outside air warms up, start the car, run it at 1500 rpm, and measure outlet temp at full cold. This way you're not introducing heat through coolant temp or solar heatimng the dash.

This will tell you if the problem is in the refrigerant loop or elsewhere. Another quick check is to see if there is condensate forming on the accumulator (if ccot type) or on the suction tube from the evap or on the tube between the R/D and evap (could be plugged R/D)

Is this a factory A/C system or aftermarket? How is temperature controled? Vacuum motor, servo motor, or bowden cable? Does the system use a TXV (R/D on the small diameter discharge tube) or orfice tube (accumulator on the suction side of the evap?)

parsonsj
07-13-2009, 06:04 AM
You really need a thermometer, but here's what Rick Love (Vintage Air VP) once told me:

Use the back of your fingers and let the vent blow on to your fingernails for 30s or so. That should make them tingle/feel numb with the cold (like when you're outside and wished you had gloves).

jp

TnBlkC230WZ
07-13-2009, 07:12 AM
I'll get a thermometer and do the tests suggested but TwentyOne. It is VA Gen 4 system for a 1st gen Camaro that I put in my Nova. They are very similar cars. I'm running a Sanden 7 series compressor that is pretty small, but it is being overdriven by the March Pullies. It is the same compressor on the front runner system and my March pullies are designed for this compressor.

Twentyover
07-13-2009, 07:21 AM
Still need the 1500 rpm. I'll keep saying it until you can show me a 28-30 psi suction pressure at idle

On a Gen IV make sure the water valve is closing

TnBlkC230WZ
07-13-2009, 07:25 AM
On a Gen IV make sure the water valve is closing

I need to check the obvious. That wire does come loose. I need to tighten it.

TnBlkC230WZ
07-16-2009, 04:55 PM
I checked the valve and the wiring is tight. I took the hose off and I'm not sure if the valve is working correctly. I see it move a little, but I believe the valve should go all the way down and stop the flow. The electric coil that controls the valve got very hot, too hot to touch.

I measured the AC temp and it was 76 degrees with an ambient temp of 83 inside my garage. The -6 line was hot and the -10 line was warm when I touched them at the fire wall. There was no condensation on the lines.

I measured the temps when the engine was still cold so the heater wouldn't be hot and it didn't get cold.

Any ideas?

dhutton
07-16-2009, 05:49 PM
Did your mechanic use the Vintage Air charging instructions and charge it with the specified amount of R134 or did he just charge it up like he does normally? VA systems run at lower pressure than most systems if I remember right. Did you give him the instructions? It clearly states 1.8 pounds of R134.

TnBlkC230WZ
07-16-2009, 08:37 PM
Did your mechanic use the Vintage Air charging instructions and charge it with the specified amount of R134 or did he just charge it up like he does normally? VA systems run at lower pressure than most systems if I remember right. Did you give him the instructions? It clearly states 1.8 pounds of R134.

Yes, I gave him the instructions. When they got done, they said the air was cold, but I've never felt cold air. They are VW factory certified techs and friends/enthusiasts. If he said it was cold when he got done, I believe him.

Twentyover
07-16-2009, 09:57 PM
Then there's a leak or another problem. The system's not working as designed.You need to get a set of gauges on the system and get pressures.

parsonsj
07-16-2009, 09:59 PM
You need to get a gauge set on it. If it was cold when they finished, then the best explanation I can see is some sort of leak.

jp

TnBlkC230WZ
08-02-2009, 12:58 PM
Ok,

I've hooked up the gauges and here is what I got.

Engine off:
Red high = 61 lbs
Blue low = 66 lbs

Running 1500 RPM
Red = 145 lbs
Blue = 5 lbs

The preasure will get higher when the fan shuts off.

Are these preasures normal? What is my next step?

Twentyover
08-02-2009, 01:12 PM
Inadequate refrigerant. Operating discharge pessure should be 250-350 psi depending on ambient temp, suction pressure about 30 psi. Your low pressure cut switch should be cycling the compressor off to protect it from burning up. There's a leak here somewhere

TnBlkC230WZ
08-02-2009, 01:40 PM
Inadequate refrigerant. Operating discharge pessure should be 250-350 psi depending on ambient temp, suction pressure about 30 psi. Your low pressure cut switch should be cycling the compressor off to protect it from burning up. There's a leak here somewhere

What is the best way to find the leak?

dhutton
08-02-2009, 02:04 PM
Did you test the system per the instructions? According to VA the high side should be twice the ambient temperature plus 15 - 20% (140 to 230 psi). Low side should be 6 to 12 psi. Windows rolled up at 1500 rpm. Sounds like you are a little low depending on your ambient temperature. Are you sure it was charged properly?

TnBlkC230WZ
08-02-2009, 02:14 PM
I trust the place that charged it. They said it was blowing cold when they got done, but I never felt cold air. Can I add refrigerant? If so do I add it until I get the needed pressures? Is there a dye that I can use so I can see where a leak might be?

dhutton
08-02-2009, 02:34 PM
You can buy refrigerant with a dye in it. You will also need a UV light to detect the leak. Auto parts stores sell both.

TnBlkC230WZ
08-02-2009, 02:59 PM
You can buy refrigerant with a dye in it. You will also need a UV light to detect the leak. Auto parts stores sell both.

Do I put it in until I get to the pressures you indicated?

dhutton
08-02-2009, 03:04 PM
Yes. Make sure you have the fan on max and set it for max cooling and that the system is blowing cold. Follow the instructions and make sure you don't overcharge it. Should not take much to get to those pressures from where you are.

Keep in mind that I'm not an expert either. I just installed the same system so I've only got a little experience. Frank is the expert, maybe he will chime in.

Twentyover
08-02-2009, 04:54 PM
Pulled out my copy of the installation instructions- Doc 3S4Orig- I am surprised by the pressure reccomendations on that sheet- At 6-12 psig , R134a boils at about -3 to 8°F (http://www.iddl.vt.edu/TEST/testhome/Test/solve/basics/tables/tablesPC/pSatR134a.html). This would cause any moisture in the system (and there is supposed to be none) to quickly freeze the valve.

This is in cntrast to factory A/C systems which cycle at 25-30 psig.

The only explaination I can come up with is the evap feeze control strategy they employ and evaporator size requires they bury the boiling point of the refrigerant well below freezing to keep the log mean temp difference between the evap and air as great as possible to get away with using the small component size they use.

The OEM systems I've worked with in the past have a very different set of parameters (greater airflow requirements necessitating larger evap core face area and using a bypass series reheat system (which I've been advised that VA also uses on the Gen IV system). No way an OEM would risk potential evaporator freeze using the pressures that VA suggests.

TnBlkC230WZ
08-02-2009, 09:10 PM
I've read the tech instructions and my preassures are low. I've should have been in the 190 - 200 range. The outside temp was about 82 -85 degrees. I'm also going to take a closer look at the water valve.

MonzaRacer
08-02-2009, 09:40 PM
Inadequate refrigerant. Operating discharge pessure should be 250-350 psi depending on ambient temp, suction pressure about 30 psi. Your low pressure cut switch should be cycling the compressor off to protect it from burning up. There's a leak here somewhere


WRONG if your running high side pressures that high its gonna stay OFF.
Proper system pressure will usually be in the 28-32 range and try to keep high side no higher than 250PSI on hot days with condenser fans on.
Unless they system is supposed to run at lower pressure but too low and your gonna starve the compressor.
AS for fans running down the road, pretty much all cars go down the road on max ac have fans on continuous, At least I know my Cavalier does and many of the cars I work on do.
I generally try to see my operating pressures at idle in the proper range THEN bring my idle up to 1500-2000 and see if it pulls down too low then cycles.
I prefer my fans keeping air flow up but depends on system design.
Two big indicators of proper system operation is this, the condenser inlet.outlet differential should be 40 degrees minimum, like 200deg in 160degree out(actual number will vary) but that constant needs to be 40 degrees approx.
Interior temp number should be 30 degrees below outside ambient on max AC with fans on high one notch down, low sides usually int the 28-32 range high side on 90+ degree days 250 with fans on but shouldnt be any higher or you dont have enough air flow over the condenser or too small of condenser.

Now get this, the outlet temps inside should have around the 30 degree split with ambient(outside).
After seeing several roadster systems I found out a lot of aftermarket systems simply are under condensed.
I put a larger higher efficiency condenser on one gentlemans Camaro with unknown brand system, got his system back into proper relationship rewired his fans(his system had normal and max AC but kept fans on continuous.
His number worked out perfect, the system had good numbers and blew 38 degrees after about 10 minutes of operation AFTER sitting outside in 90+degrees and his car is black on black on black. Interior temps was 178degrees(he now has tinted windows) after I came back from lunch.
I had system operating and finished before going to lunch.
It was a mechanical h-block/expansion valve system and never dropped pressure after revved up.
Reason for condenser change was because it had literally blew apart 2 previous compressors.
He has since drove through death valley and had cold air in the 40s all the way.

TnBlkC230WZ
08-03-2009, 07:01 AM
The charging instructions say the high side should be ambient temp * 2 + 15-20% so that would be (85 degrees * 2 *1.2) = ~200

TnBlkC230WZ
08-03-2009, 05:54 PM
I charge the system this evening. The high side is 205 lbs and the low side is 18 lbs and I've got cold AC again. I'll keep an eye out for leaks.

dhutton
08-04-2009, 09:49 AM
If the shop that did the charging had pulled the system down with a vacuum pump they should have found the leak if there is one. Do you know if they did? If they didn't there may be moisture in the system.

TnBlkC230WZ
08-07-2009, 05:39 PM
The leak is in the middle of the -8 line going from the condensor to the compressor. The good news is it is easy to get to. Since I have to purge the system, I'll put a new drier in and move it under the hood. I currently have a splice in the -6 for the trinary switch so I will be able to get rid of that. I will have a one peice -8 line made. I got lazy on the two piece. I may also try to put a bigger condensor in if I can figure it out. From what I've read, it will help make it colder. I'll start a new thread on the upgrades.

It may not of leaked when they charged it. The -8 line is two pieces. They are joined under the core support and the nut is in between the frame and core support. It could have easily banged against the frame and came loose. The one peice line should fix that.

TnBlkC230WZ
09-02-2009, 04:18 PM
Finally got the -8 hose fixed. The mechanic said the Parker rubber hoses in the VA kit are notorious for leaking. He replaced it with a new Goodyear hose and all is great.

KUL FIR CHICK N
09-03-2009, 02:06 PM
You're mechanic is an idiot.

He certainly doesn't know enough about A/C to be messing with it. I won't bash on your friend, but he's not doing you any favors.

Parker hoses are not "notorious" for leaking. Parker and Goodyear both have excellent hose, neither has any problems with leaking. Your mechanic should have leak checked your system before the car left his shop.

Your best bet would be to seek out a shop that specializes in AC only. Better yet, find a Vintage Air dealer/installer.

The Gen 4 heater valve is a normally open valve. It must be powered to close. It will get too hot to touch under normal operation.

You MUST have your door panels, rear seat, carpet, insulation, seals, etc installed or you're never going to be cool. There's just too much loss through all of those exposed panels/gaps to let your car ever cool down.

BTW Greg, we run a thermister mounted in the evaporator coil so that we can sense a freeze condition. Our pressures generally run considerably lower than CCOT systems that are cycled only by suction pressure.

TnBlkC230WZ
09-06-2009, 06:45 AM
He certainly doesn't know enough about A/C to be messing with it. I won't bash on your friend, but he's not doing you any favors.

Parker hoses are not "notorious" for leaking. Parker and Goodyear both have excellent hose, neither has any problems with leaking. Your mechanic should have leak checked your system before the car left his shop.

Your best bet would be to seek out a shop that specializes in AC only. Better yet, find a Vintage Air dealer/installer.

The Gen 4 heater valve is a normally open valve. It must be powered to close. It will get too hot to touch under normal operation.

You MUST have your door panels, rear seat, carpet, insulation, seals, etc installed or you're never going to be cool. There's just too much loss through all of those exposed panels/gaps to let your car ever cool down.

BTW Greg, we run a thermister mounted in the evaporator coil so that we can sense a freeze condition. Our pressures generally run considerably lower than CCOT systems that are cycled only by suction pressure.

It was the hose maker that was commenting on the hoses, not the mechanic. He could be biased as he is selling Goodyear. The Parker hose that VA crimped did leak so at least it is fixed. It cools the car now without the door panels installed so I'm happy. They system really works good.

Unfortunately I've only found one VA dealer within 50 miles of me and it is inconvienently located. Otherwise, I would have taken it there.