Damaged AC fitting bolt hole

[Genesis]

The pressure has to be ~35psi or so for the compressor to come on; there is only one pressure sensor on the ALH cars, on the high side. So yes, if there was no refrigerant added it won't engage (and neither will the fans, so if you push in the switch, turn on the cabin fan, and ignition ON -- but not running -- if the system is entirely empty the fans will NOT run on low)

 

[wonneber]

There's a sticky at the top of this forum list how to test the fans.

 

[intro]

There's a sticky at the top of this forum list how to test the fans.

Is it safe to do this with compressor plugged in and an uncharged system?
All this time I've had it unplugged so I wouldn't accidentally press the button in the cabin. I thought I read that somewhere? The last time I tested the fans there was still refrigerant in the system, now it's empty.

 

[Genesis]

The fans will not engage without refrigerant in the system (pressure sensor reading too low.)

 

[intro]

The fans will not engage without refrigerant in the system (pressure sensor reading too low.)

So really, what I need to do is go back and tell the Sears guys, the reason there was no power to the compressor is because you didn't start filling up the system? Is this car unique in this way that they would have overlooked something as crucial as this?

I did go out before reading this and took the chance when I realized the compressor wouldn't actually be spinning anyway with the car off. Fans did not turn on but that tells me nothing at this point based on what you're saying. Years ago I had been able to rule out the fans, I think I might have repaired one of them, can't remember.

Fuses look good.

 

[jokila]

So really, what I need to do is go back and tell the Sears guys, the reason there was no power to the compressor is because you didn't start filling up the system? Is this car unique in this way that they would have overlooked something as crucial as this?
I did go out before reading this and took the chance when I realized the compressor wouldn't actually be spinning anyway with the car off. Fans did not turn on but that tells me nothing at this point based on what you're saying. Years ago I had been able to rule out the fans, I think I might have repaired one of them, can't remember.
Fuses look good.

The system is loaded with freon when it is completely turned off after the vacuum pump has ran for sufficient time to purge the system of moisture. They then add 750 grams, by weight, of the freon, then they can turn on the system. There would be no reason to have turned it on with no freon.

 

[intro]

The system is loaded with freon when it is completely turned off. They measure 750 grams by weight of the freon, then they can turn on the system. There would be no reason to have turned it on with no freon.

Thanks, I'm just a little unclear on the process/machine they are using I guess, which probably isn't helping. I just got off the phone with them, the guy who had the problem isn't in until tomorrow. They're saying that after the successful evacuation they would have started filling it. I'm not too clear where they encountered the problem or if the guy just looked down and saw that the compressor wasn't engaged so he quit early. It seems like it's all automated on these machines right? It finishes, holds pressure and then they just press a button and fill it with Freon? When I went into the bay to take a look he claimed he had metered the wire going to the compressor and there was no power going to it, I had zip-tied the connector on because it wouldn't click, it seemed undisturbed.

 

[intro]

The system is loaded with freon when it is completely turned off after the vacuum pump has ran for sufficient time to purge the system of moisture. They then add 750 grams, by weight, of the freon, then they can turn on the system. There would be no reason to have turned it on with no freon.

I see what you're saying. The car is filled with Freon before they ever even try turning on the car and the compressor? This just makes even less sense then, because according to them they only did the evacuation (that's what I was charged for) and didn't continue with the adding of refrigerant.

 

[Genesis]

If they just evacuated it then it should not have run when they started it.

The same is true on my truck, incidentally; no charge, no run at all. The truck (a GM) has a sensor on the low side so when filling it the compressor will cycle until the low side pressure, while running, is high enough for the clutch to remain engaged. It also has a high-side sensor and clutches the compressor on and off during normal operation (depending on the temperature of the cabin and where the dial is set, of course) -- as does my Mazda, although I've never had a reason to screw with that car or take it to someone for A/C work as it's reasonably new and everything works. The ALH only has a high-side sensor and the compressor is variable-displacement so once it comes on it should stay on since once it comes on the pressure will rise, of course, on the high side. The only thing that should kick off an ALH compressor with the button in if there's refrigerant in the system is if ambient temperature is too low, during full-throttle pulls or if the coolant temperature gets too high (in those cases the ECU will shut the clutch down.)

It makes no sense that they evacuated the system, put nothing in it, then said "it doesn't run so it's broken" in short -- I can't speak to all auto A/C systems but certainly neither my truck or ALH will pull in the compressor with no refrigerant in them.

 

[intro]

If they just evacuated it then it should not have run when they started it.

The same is true on my truck, incidentally; no charge, no run at all. The truck (a GM) has a sensor on the low side so when filling it the compressor will cycle until the low side pressure, while running, is high enough for the clutch to remain engaged. It also has a high-side sensor and clutches the compressor on and off during normal operation (depending on the temperature of the cabin and where the dial is set, of course) -- as does my Mazda, although I've never had a reason to screw with that car or take it to someone for A/C work as it's reasonably new and everything works. The ALH only has a high-side sensor and the compressor is variable-displacement so once it comes on it should stay on since once it comes on the pressure will rise, of course, on the high side. The only thing that should kick off an ALH compressor with the button in if there's refrigerant in the system is if ambient temperature is too low, during full-throttle pulls or if the coolant temperature gets too high (in those cases the ECU will shut the clutch down.)

It makes no sense that they evacuated the system, put nothing in it, then said "it doesn't run so it's broken" in short -- I can't speak to all auto A/C systems but certainly neither my truck or ALH will pull in the compressor with no refrigerant in them.

Thanks! I'm guessing AVH/AZG is the same. This is a gasser wagon.

 

[AndyBees]

I installed a new Compressor on my previously owned 2000 Jetta about 6 weeks ago (leaky body seals and shaft seal).

After pulling a vacuum for about an hour, I started the engine, turned ON the AC.... obviously no Fans and no kick-in of the Compressor. But, as I was adding the first can of R134a, the Fans and Compressor kicked ON for a few seconds then back OFF.... did this a few more times as the refrigerant was going in... Then, they stayed ON as I completed the charge. That's how it is suppose to work. (2.5 cans of R134a will put the system in the ball park).

Fast forward to date ... cools just fine on these high 80s and low 90s days with high humidity.

 

[intro]

I installed a new Compressor on my previously owned 2000 Jetta about 6 weeks ago (leaky body seals and shaft seal).

After pulling a vacuum for about an hour, I started the engine, turned ON the AC.... obviously no Fans and no kick-in of the Compressor. But, as I was adding the first can of R134a, the Fans and Compressor kicked ON for a few seconds then back OFF.... did this a few more times as the refrigerant was going in... Then, they stayed ON as I completed the charge. That's how it is suppose to work. (2.5 cans of R134a will put the system in the ball park).

Fast forward to date ... cools just fine on these high 80s and low 90s days with high humidity.

Thank you! Really looking forward to having AC again for the first time in years.
I'm wondering if I should even trust that these guys at Sears evacuated the system properly after all this. I guess that would be kind of hard to mess up if there's a machine measuring everything.

 

[jokila]

It's important that the system not be overfilled. It's easy for them to weigh the freon tank or can and know how much is added. This system isn't one of those "keep adding until it gets cold enough". It's specific. 750grams.

 

[intro]

It's important that the system not be overfilled. It's easy for them to weigh the freon tank or can and know how much is added. This system isn't one of those "keep adding until it gets cold enough". It's specific. 750grams.

I will specify the amount.

 

[Genesis]

It's on the sticker under the hood. 750g with a maximum tolerance of +50 for the ALH.

(Which works out to two WallyWorld cans + 100g out of a third, and you're right up the middle of the tolerance band.)

 

[intro]

It's on the sticker under the hood. 750g with a maximum tolerance of +50 for the ALH.

(Which works out to two WallyWorld cans + 100g out of a third, and you're right up the middle of the tolerance band.)

Should I be trying myself since the system was evacuated? I'd still need to invest in gauges though right?

 

[Genesis]

Yes (plus a gram-reading scale -- a digital postal scale that can read to 2lbs will do), and you really want a vacuum pump because you want to get air out of the hoses before you start putting the refrigerant in. If this is the only car you expect to do this with, and only the once it won't be cost-effective to buy the gear.

 

[intro]

Yes (plus a gram-reading scale -- a digital postal scale that can read to 2lbs will do), and you really want a vacuum pump because you want to get air out of the hoses before you start putting the refrigerant in. If this is the only car you expect to do this with, and only the once it won't be cost-effective to buy the gear.

I will be doing the heater core on my ex's Passat at some point (jb-weld fix has a pinhole leak after 5 months), but I think I'll leave the ac service to the guys with the fancy equipment for now.

 

[AndyBees]

I agree 100% that the system "should" have the manufacturer's recommended amount of refrigerant. However, I've seen stickers with a Plus or Minus number. Example, the 2008 VW EOS sticker is something over 500 grams with a plus or minus of 25 grams (have photo somewhere). That's almost a 10% swing from low to high and I suspect the tolerance can be a little more either way. What pressure does the sensor switch say no? Is it within that minimum/maximum range or slightly less/more? And, no doubt ambient temp plays a role.

As for weighing the amount going in (which I agree is the industry standard procedure), well, it's only as good as the guy doing the job. The hose connected to the tank sitting on he scales will affect accuracy. Disconnecting the hose to make sure the weight calculation is correct invites air into the system if reconnecting is necessary.

I've rejuvenated several of the AC systems on these MK4s with great success. It is not rocket science. But, you need the correct tools and some general knowledge of the system as well as how AC works. I've changed over numerous MK1 Rabbits and Jettas with excellent success.

Example: There is really no info (certified) on my Vanagon with an SD 7V16 compressor (same as on OPs car) relating to the "correct" amount of R134a refrigerant. The hoses from front to rear are far longer than what's in any MK4 vehicle. But, I have it putting out nice cold air on 90f plus days. It takes approximately 2.75 cans (12 ounces [340 grams] per can). Installing R134a is a very slow process beyond the first can starting with 29 inches of vacuum. I end up with roughly 40 PSI low side pressure and 225-240 PSI high side pressure with an ambient temp of 85f. Those numbers on pressure and temp are extremely close to what I achieved with my Blazer after replacing the compressor (no complaints from the wife).

To the OP, I'd never trust a vacuum on the system unless I was looking at it on a set of Manifold Gauges. In fact, the manifold gauges should never be removed after pulling a vacuum unless it is obvious there is a leak. Otherwise, once the vacuum is pulled, the refrigerant should be introduced.

 

[intro]

I agree 100% that the system "should" have the manufacturer's recommended amount of refrigerant. However, I've seen stickers with a Plus or Minus number. Example, the 2008 VW EOS sticker is something over 500 grams with a plus or minus of 25 grams (have photo somewhere). That's almost a 10% swing from low to high and I suspect the tolerance can be a little more either way. What pressure does the sensor switch say no? Is it within that minimum/maximum range or slightly less/more? And, no doubt ambient temp plays a role.

As for weighing the amount going in (which I agree is the industry standard procedure), well, it's only as good as the guy doing the job. The hose connected to the tank sitting on he scales will affect accuracy. Disconnecting the hose to make sure the weight calculation is correct invites air into the system if reconnecting is necessary.

I've rejuvenated several of the AC systems on these MK4s with great success. It is not rocket science. But, you need the correct tools and some general knowledge of the system as well as how AC works. I've changed over numerous MK1 Rabbits and Jettas with excellent success.

Example: There is really no info (certified) on my Vanagon with an SD 7V16 compressor (same as on OPs car) relating to the "correct" amount of R134a refrigerant. The hoses from front to rear are far longer than what's in any MK4 vehicle. But, I have it putting out nice cold air on 90f plus days. It takes approximately 2.75 cans (12 ounces [340 grams] per can). Installing R134a is a very slow process beyond the first can starting with 29 inches of vacuum. I end up with roughly 40 PSI low side pressure and 225-240 PSI high side pressure with an ambient temp of 85f. Those numbers on pressure and temp are extremely close to what I achieved with my Blazer after replacing the compressor (no complaints from the wife).

To the OP, I'd never trust a vacuum on the system unless I was looking at it on a set of Manifold Gauges. In fact, the manifold gauges should never be removed after pulling a vacuum unless it is obvious there is a leak. Otherwise, once the vacuum is pulled, the refrigerant should be introduced.

Interesting use of the mk4 set up on your Vanagon. How do you like that motor conversion? I've heard it is not an easy swap and pricey. I picked up an 85 this past spring and am debating an abs with diesel components or a Subaru motor, leaning towards a 2.2 Subie.

I would think they will pull a vacuum again before charging it, I hope so.

 

[intro]

Absolutely ridiculous. Went back in to do this over at the Sears Auto Center. They insisted they added refrigerant and the compressor wasn't kicking in, so they drained it out again.

I insisted they do it over to ensure they filled it completely and that they'd have to evacuate it again on their own dime and then charge me for adding the refrigerant, that I needed the freon in the system no matter what so that I could troubleshoot correctly. I was very clear how all the systems were connected. The back and forth got loud as they refused to do it over. Finally they offered to refund me on the evacuation so I could take it somewhere else.

So here I am, with 3-4 hours wasted, still with an empty system.

My only fear is that the new compressor that's been sitting in the car the last 3 years was DOA and I didn't realize, or that the connector not clipping on to the compressor is the problem, but the fans aren't turning on so that would lend itself to the low freon argument-unless everything is toast, which is unlikely I would think.

Isnt it bad for the compressor to run 12v to it directly if it's empty? Guess I'll waste more time tomorrow and try a different Sears.

 

[Genesis]

If the compressor is not coming on and the fans are not running on an ALH with the button pressed the ignition ON (and engine running for the compressor):

1. There is no refrigerant in the system (less than ~35psi with the system OFF on the high side)
2. There IS refrigerant in the system but the (single) pressure sensor on the high side is bad; there is a wiring fault or it is either reading too low or extremely high (the ECU will NOT command the system or fans on.)
3. There IS refrigerant in the system and the pressure sensor is working properly but the AMBIENT temperature sensor says it is too cold outside (failed, not working properly, wiring fault, etc) and the ECU is preventing it from engaging.
4. There IS refrigerant in the system, the ambient sensor says the temperature is high enough and the pressure sensor is working, BUT the FCM is not providing drive current to the fans AND compressor clutch coil (BOTH circuits have failed.)

 

[intro]

If the compressor is not coming on and the fans are not running on an ALH with the button pressed the ignition ON (and engine running for the compressor):

1. There is no refrigerant in the system (less than ~35psi with the system OFF on the high side)
2. There IS refrigerant in the system but the (single) pressure sensor on the high side is bad; there is a wiring fault or it is either reading too low or extremely high (the ECU will NOT command the system or fans on.)
3. There IS refrigerant in the system and the pressure sensor is working properly but the AMBIENT temperature sensor says it is too cold outside (failed, not working properly, wiring fault, etc) and the ECU is preventing it from engaging.
4. There IS refrigerant in the system, the ambient sensor says the temperature is high enough and the pressure sensor is working, BUT the FCM is not providing drive current to the fans AND compressor clutch coil (BOTH circuits have failed.)

Genesis, really appreciate all your help. So is the next order of business to get it charged with 750g freon? They already had confirmed no leaks. If it works, great, if not, I have some testing to do.

Would I need to get the 2nd evacuation done now or can I just request the charge this time, moreso in the interest of time than $$$. I'd rather spend that hour troubleshooting than sitting waiting for evacuation to be done. Seems like the vacuum is part of the charging service anyway.

 

[Genesis]

Pulling the vacuum for a few minutes prior to putting the refrigerant in is part of the deal because you need to get the air out of the lineset on the gauges (there's some in the hoses) before you put the refrigerant in.

It's sort of tricky to charge without the compressor running unless the place doing it has a pump to force the charge in as opposed to simply hooking their source bottle to the lineset. It certainly can be done but what will happen is that as the refrigerant goes in the temperature in the source can goes down (adiabatic expansion; this is how an A/C unit works in the first place) and the pressure of the gas falls; when that reaches equilibrium with the gas in the system flow stops until the liquid that got cold in the source can warms up again.....

 

[wonneber]

It's to bad it turned into a ruckus at Sears.
I don't see why they didn't talk to you first before evacuating the system of the Freon they put in.

I personally would have paid them to leave the Freon in so I could continue.

Maybe the next place give them the story and explain you know the compressor has an issue.

Another thought, maybe jump the low pressure sensor (after checking it has power to it) so the compressor should run then trouble shoot it?

 

[AndyBees]

Intro, the ALH in my Vanagon is awesome. I put it on the road mid-to-late August, 2012. I've put over 82k miles on it. I just finished doing a long list of maintenance on it, including a re-work of the wiring relating to the Cruise Control.

I made a number of mistakes along the way. But, that is how you learn.

You can do a search and find my Build Thread. It is very long and loaded with pics.

I'll share this piece. 215/75/15 tires, air-cool DK tranny [4.57 R&P, 0.77 4th gear and 1.14 3rd gear]. In 4th gear, at about 3125 RPMs speed is 70mph (GPS verified). Other than welding, I did all the work myself. I've pulled a popup camper to Alaska twice with it....... over 25 MPG pulling the camper. Look for my 2014 & 16 Road Trips... stats in there.

Different topic: Does anyone know why there are no signatures at the bottom of our posts in this Thread?

 

[Genesis]

It's to bad it turned into a ruckus at Sears.
I don't see why they didn't talk to you first before evacuating the system of the Freon they put in.

I personally would have paid them to leave the Freon in so I could continue.

Maybe the next place give them the story and explain you know the compressor has an issue.

Another thought, maybe jump the low pressure sensor (after checking it has power to it) so the compressor should run then trouble shoot it?

There is no low-pressure sensor on an ALH.

There is ONE sensor, it's a PWM sensor (thus you CAN'T jump it), and it's on the high side.

 

[AndyBees]

Genesis, but doesn't that sensor respond to low pressure?

As I commented in a previous post, after installing a new compressor, as I was charging with refrigerant the AC and Fans kicked on for a few seconds and then back off and on, etc., until they finally stayed on (engine running and everything On). I attributed that to increased pressure above the minimum. What am I missing?

 

[Genesis]

Yes, but it's on the high pressure side of the system -- and it's the only one on the stock setup. I don't know what you have on the Vanagon or where the switch is on it, but on my ALH it's on the high pressure side just before the TXV, and thus once it allows the compressor to pull in (around ~35psi) it will remain on unless you have a blocked TXV or similar and it trips off on excessive (high) pressure.

I recently basically completely disassembled the system on my ALH, other than the evaporator in the cabin, flushed everything and replaced the compressor, dryer and TXV along with all the O-rings, so I got a real good look at exactly what is where.

 

[AndyBees]

What I was referring to installation of a new AC Compressor on my 00 Jetta.

The Vanagon does not have a pressure switch, FCM, or ambient air temp switch. It is as basic as they come. I even removed the PCV from inside that SD 7V16 compressor so it would function like the OE compressor that come on the Vanagon.