Delayed Air Conditioning

[robrichtx]

Weird one here folks - it seems that my AC begins to cool only after the car has run several miles. It's been like this for over a year, and it's really more of an annoyance than anything else. This condition only happens after the car has been sitting for a day or so. The AC works immediately once the car has been warmed up, or if the car has only sat for an hour or two.

Anyone else experience this? My wife's 2006 never seems to have this problem.

Time to recharge the AC? I'm loathe to do that, as it's probably special refrigerant, right

Rob

 

[christylea]

I JUST took mine in for this. At first I thought I was losing my mind, but after a hot hot weekend in Dallas shuttling friends from the Midwest around to & from a wedding I decided it was a real issue. I took it in yesterday morning and got a call in the afternoon that they weren't able to replicate the issue or see any codes come back from the scan. I asked them to keep it overnight and try again this morning. Sure enough, I just got a call from the Service department saying that they were able to replicate the issue: pressure-buildup in the a/c compressor. They said they were replacing it.

I know relatively little about the inner workings of automobiles (though I think I'm pretty savvy compared to your typical 27 y/o female). I had looked for this issue here before I took it in and just jumped on to share my findings so someone might benefit since it was so tricky to diagnose. I didn't see this post then but here it is now. Even in Austin! Take it to Hewlett and they should know just what your issue is now. More likely -- you can replace this yourself.

 

[Tim Birney]

Weird one here folks - it seems that my AC begins to cool only after the car has run several miles. It's been like this for over a year, and it's really more of an annoyance than anything else. This condition only happens after the car has been sitting for a day or so. The AC works immediately once the car has been warmed up, or if the car has only sat for an hour or two.

Anyone else experience this? My wife's 2006 never seems to have this problem.

Time to recharge the AC? I'm loathe to do that, as it's probably special refrigerant, right

Rob

Always let the car (U.S./Japanese/German) get to normal operating Temperatures,,,, then turn on the Air.

 

[glandpuck]

This problem has been described elsewhere on the forums. people with Climatronic AC systems have been noticing a delay of from 4 to 10 minutes before cooling begins. Also, the AC doesn't seem to get as cold as when the system was functioning properly. The vent air temps should be as low as 36 degrees even in southern heat when the car is freeway driven. A Vag-Com will help if you monitor the HVAC system. Also, it appears that the compressor is not completely pressurizing to the fullest extent, maybe 10 N-M instead of a 17 - 18 N-M. When gauges are put onto the compressor, the low ports read maybe 50 and the high port 175-200 and stays steady. The problem then does not appear to be a leak as even if the system is vacuumed out and R134a re-installed to spec, the same condition exists. Of interest to know, is what brand of compressor was installed on the car: Zexel, Denso or Sanden and what brand was the replacement. Also, if possible, those persons with a VAG-COM should try to monitor the HVAC temps, pressures, amperages, etc. and post to the forum so we can begin to establish what is normal for a Climatronic and how to determine exactly when failure is occurring. Also, if possible, try to retain the replaced compressor so it may be torn down and inspected for design failures or rebuilding in the near future.

 

[unsub1]

robrichtx, Hmm, mine takes a minute to kick in but I didn't really question it. Figured the car had to get going or something. I see a theme here; me, you and christylea all live on the surface of the sun, so maybe that's it.

 

[Mach1]

Both of mine have delays, but that is the delay on, of the system..It takes about 1/4 to 1/2 mile before they start pushing some cold air..at about 3 miles, they are both pushing some very cold register air..

 

[Mach1]

Rob/others, are both of your fans running??? I could see a cooling/delayed problem if you aren't moving enough air across the condensor..

 

[christylea]

Yah, both fans were running. And the air was always very cold when it did get cold.

Glandpuck, godo info. Unfortunately, my previous compressor is gone. I could probably glean some sort of info from the service receipt about then new one if anyone is curious.

 

[DanG144]

Knowledge is power.

Please let us know what they find, compressor data, who made it, model.

I would love to take one apart and see what was wrong (or at least try to see what was wrong.)

I think I know, but I would like to verify.

Anytime the compressor is failed and they put a new one in, try to ask questions that will ensure they do a good and thorough flush on the system.

Otherwise, the compressor will last about as long as the warranty, then fail due to bad oil or metalic particles in it.

 

[hid3]

I'm having the cooling delay too! This year it got even worse. I think I'm not getting *cold* air at all, just mild instead. I've checked with VCDS (Engine Group 063 block 1) with A/C on and off. In both cases Refrigerant pressure was within specs. Should I woory about it?

 

[DanG144]

This seems to be very common with the A5 chassis and the newer compressors.

I would definitely worry about it if I was under warranty, and if my compressor needed replacing, I would try to get a Sanden pump over one of the others.

If the compressor has broken a rod, or has some other mechanical failure that is shedding metal particles, the sooner you flush it and replace it the better. If the only problem is that the electrically operated control valve is failing, then you can run it as long as it is cooling enough to get you by.

The problem is we are not sure of the failure mechanism. Some Zexel compressors are known to be problems. I think Audi has a bulletin out on them.

Another thread on A5 air conditioners. I hope to do more with this before next summer.
http://forums.tdiclub.com/showthread.php?t=253641

 

[hid3]

1. How do I know what compressor do I have (w/o disassembling everything, of course)
2. are there any diagnostic procedures to diagnose possible A/C compunent failures? (And yes, my BOTH A/C fans are spinning at both slow and high speed; triple-checked that).

 

[chemeng1661]

I have the issue as well. On very hot days (like it has been in NJ for the past week), it takes awhile (about a half mile) for the air to blow ice cold.

Also, over the past week, I noticed that the air periodcally starts to blow warmer, especially when at slower speeds (bumper to bumper traffic), then it gets ice cold again. It is really annoying. I haven't observed this before on the car.

I checked the fans twice on my most recent trip home and both were running. I really do not feel like visiting the dealer's service department for this. I have 5100 miles on the car.

 

[philip_g]

I do not have the climatronic system and my car is the same way.
At a light there's little to no cooling, once you hit the highway it freezes you out.
Both my fans are running.

 

[glandpuck]

Just a thought as I get ready to have some parts replaced: Could it be that the delayed start of the cold air and the air not getting very cold is in fact not a compressor issue at all but an issue with a stuck expansion valve? In my exchanges with DanG144, my reading of the Sanden site and speaking with some purportedly intelligent folks who sell these compressors, I am beginning to think that the compressors are maybe not at fault. First of all, the compressor in an A5, if it is a Sanden, is a PXE variable displacement unit and is in effect one of their most advanced models. That doesn't mean it cannot have design flaws, but it has been designed with many safeguards to prevent mechanical failure. Now in my system, my AC takes a while to come on, as long as up to 8 minutes and then the air temp only goes down to 54 degrees. However, that is still as much as 45 degrees below the ambient air temp and my high pressure port reads 200. So, my compressor is compressing as it should be. I would like to hear from those folks who were told their compressors were broken, but they cooled this much. It just doesn't make sense to me that a broken compressor would work to this degree. Next, I have learned that my low port pressure was 50. According to those who "know", it should be 20. This means the pressure into the evaporator is okay, but out of the evaporator is too high and would explain the air getting cool, but not maximally into the high 30's. As R134a leaves the evaporator, it passes through the expansion valve again enroute to the compressor. This higher pressure transmitted to the evaporator prevents maximal cooling and also might explain the delayed startup as the pressure it too high on the low side.

Also, I am not certain why a system would need to be backflushed and flushed if the problem just requires replacement of the expansion valve and drier cartridge. If in fact there is no mechanical failure of the compressor, where would the metal contaminants come from to ruin the new compressor?

My dealer quoted ~$1300 for compressor, expansion valve and drier replacement. I am going to replace the valve and drier, recharge the system and see if this solves the problem. If it turns out that I really needed a heart transplant (compressor), then I will put that in, but at least I will know for certain what the problem was in the system and might wind up saving a ton of cash.

Any thoughts on my conceptualization of this problem would be appreciated.

 

[DanG144]

Glandpuck,
I hope you are correct, but I am not quite so sure. It is true that the suction pressure should be 25 or so.

The suction pressure is created by the compressor pulling the refrigerant out of the suction side.

This compressor capacity is varied to maintain suction pressure. From your operating data files we saw the compressor maintaining full demand continuously. If it was working properly it would pull suction pressure down and then the demand would drop when proper suction pressure (actually controlled by temperature) was met.

So it is very difficult to make the call.
The compressor is definitely able to produce a good discharge pressure, but it is not able to pull the suction pressure down. Is it because the compressor is not at full capacity as demanded? Or is the thermal expansion valve putting so much flow through it that the compressor operating at full capacity is not able to keep up?

It is not really possible to be sure.

If you were doing your own work, I would suggest you do exactly as you are doing. Then replace the compressor later if you need to.

One thing that could occur is that they could pull the compressor discharge line and find metallic particles in it, and know you need a new compressor.

The other is you find no indications, then it simply works the same as it did before.

I do not know what your labor charges are, but you may have to buy a second drier and go through this again.

The vendor may know more about this than I do - he should. I just started learning about these AC systems in the last two years. Hopefully he is correct. He is obviously a good guy or he would sell you the compressor anyway. He has no incentive to mislead you.

Can I ask you what the compressor would cost?

I plan to do two things. One is to review your data files to make sure my memory is correct. The other is to review the troubleshooting guide I have from Bentley or EBahn.

 

[DanG144]

Bob,
You do not need to do the flush unless you replace the compressor, and you find either overheated oil or metalic particles in your old compressor.

A flush lets you remove all the old oil and replace it with new. This lets you ensure you have exactly the right amount of oil. Too much oil and you get poor cooling performance, too little and your compressor dies an early death.

So it depends upon what you find in the system and compressor. If the oil in your compressor is clear golden and has no metal in it, then you do not need to do a flush, unless you are concerned that your oil content has gotten out of whack.

 

[Tim Birney]

Always let the car (U.S./Japanese/German) get to normal operating Temperatures,,,, then turn on the Air.

I will say it one more time...

 

[Mach1]

Tim, that is sound advice..The delay is buillt in there for several reasons.

 

[john_tsouris@hotmail.com]

I have an 06 TDI which just turned 130,000. For the past month, I have started to have delayed AC turn-ons.

Hint-Hint The parts guy at the dealer, when asked, indicated that the #1 AC part that they supply to the service department is high/low pressure switches.


I dread taking the car to the dealer, as my dealer, Flow motors in Greensboro, I think is the biggest bunch of unscrupulous scumbags on the planet. I guarantee if the AC needs a 50 cent part, they will quote a new compressor for $2,000. I'll have to find an import AC local guy shop.

 

[DanG144]

1. How do I know what compressor do I have (w/o disassembling everything, of course)
2. are there any diagnostic procedures to diagnose possible A/C compunent failures? (And yes, my BOTH A/C fans are spinning at both slow and high speed; triple-checked that).

Jerry,

1. On every car I have seen that has a Sanden compressor there was a large, clear nameplate with all of the data on it. This was easily visible without dismounting the compressor, but I think you had to remove the belly pan or use a mirror. (And I found it very hard to read the numbers etc in a mirror.)
   I think the other manufacturers have smaller and less clear methods. Some use a metal tag on a screw or bolt.
2. You can log data from your AutoHvac module. pressure, evaporator temperature, control signal (spec and actual), along with RPM were all good tools.
3. This is assuming you have either the Climatic or the Climatronic AC, which is all I have seen on the 2005.5 and later Jetta's in the USA.
4. If you never see your compressor control signal decrease from maximum, then the evaporator temperature is never getting down to target temperature (which is inherently a target pressure, too.)

 

[DanG144]

cycling compressor

Glandpuck,
In one of your recent posts or PMs you had mentioned that your compressor was cycling. Could you post more on that?

These A5 electrically modulated compressors should not cycle on and off, just modulate displacement.

Dan

 

[DanG144]

Always let the car (U.S./Japanese/German) get to normal operating Temperatures,,,, then turn on the Air.

Tim, while this sounds good, why do you say this? Is it for the car or for the AC?

The AC load is much less than the operating loads. Do you wait to move your car until it is warmed up? Moving the car is a much greater load than the AC.

The AC is a more constant, small load that will aid in warming up your engine.

I have never heard this advice before, and would really like to know.

 

[hid3]

Latest news from my Climatic's diagnostics today. The label file in question is 1K0 820 047 (Component: Climatic PQ35 084 0404).

So I set fan setting to "2" and the coolest setting, drove about 20 secs and turned the A/C on. After about 30-40 seconds since that it started to blow cooler than ambient air.

Drove 6 miles city traffic from my workplace to garage. Ambient temps were about 22-24 C. Arrived to garage, ambient temp was 19.5 C according to instrument cluster. Hooked up VCDS:

Engine, Group 063:
1. Refrigerant pressure: 10.09 bar
2. Load Torque: 4 Nm
3. -
4. -
 
Auto HVAC:
 
MVB 001,1: Code for compressor: 0
MVB 001,2: Engine speed: 800
MVB 001,3: Driving speed: 0
MVB 001,4: Standing time: 3:59
 
MVB 002,1: Compressor current (actual): 0.665 A
MVB 002,2: Compressor current (specified): 0.685 A
MVB 002,3: Compressor rotations: 1000
MVB 002,4: Compressor load: 5
 
MVB 003,1: Coolant pressure: 10.6 bar
MVB 003,2: Radiator fan (actual): 44%
MVB 003,3: Radiator fan (spec): 43%
MVB 003,4: Engine speed: OFF
 
MVB 004,1: Outside temp, unfiltered: 26
MVB 004,2: Outside temp, regultaion: 19
MVB 004,4: Coolant temp: 85
 
MVB 005,1: Outlet blower temperature: 4
MVB 005,3: Footwell Blower temperature: 12
 
MVB 006,1: Temperature behind condenser: 3
MVB 006,2: Interior temperature: 21
 
MVB 011,2: 100
 
MVB 012,1: 27
MVB 012,2: 31
MVB 012,3: 31
MVB 012,4: 224

Hope this might help for someone...

And after I finished doing these tests I could see a little puddle under the car (about under passenger's feet).

 

[hid3]

Jerry,

1. On every car I have seen that has a Sanden compressor there was a large, clear nameplate with all of the data on it. This was easily visible without dismounting the compressor, but I think you had to remove the belly pan or use a mirror. (And I found it very hard to read the numbers etc in a mirror.)
   I think the other manufacturers have smaller and less clear methods. Some use a metal tag on a screw or bolt.
2. You can log data from your AutoHvac module. pressure, evaporator temperature, control signal (spec and actual), along with RPM were all good tools.
3. This is assuming you have either the Climatic or the Climatronic AC, which is all I have seen on the 2005.5 and later Jetta's in the USA.
4. If you never see your compressor control signal decrease from maximum, then the evaporator temperature is never getting down to target temperature (which is inherently a target pressure, too.)

According to ETKA my car is equipped with SANDEN compressor p/n 1K0 820 859 F. There were no recalls for it.

Unfortunately I can't inspect my compressor from under the car. Besides I doubt I could find there anything visible: I othen drive through dusty and muddy country roads (off-road) and there's lot of dirt stuck to oil pan, tranny and of course the compressor. Thanks for directions though. I'll try to find/inspect the plate during my next oil change.

 

[christylea]

Not sure if part number alone is enough to know which brand of compressor I now have, but it's 1K0-820-859-F.

Additionally, the notes do say that a valve in the compressor was sporadically sticking. This note is preceded by a number, 5374. Not sure if that number is useful or just something that the invoice software inserts but thought I would include it.

 

[chimmike]

I will say it one more time...

that's all good and nice to say, but when the interior of your car reachest 130* for 9+ months out of the year, the last thing you want to do is wait a few minutes while driving around to turn your a/c on. No thanks. By that time, I'd be soaked in my own sweat (no, I'm not exaggerating either)

 

[Rauss]

This is a new generation fuel efficient ac system... that`s why. It use the heat of the motor, and exchange air from outside to create cold air... sucks but fuel efficient... want some ac power get a old GMC or something like this.

 

[Antsrcool]

old fords 87 to 93 had the best a/c my 88 towncar woudl blow frost out of teh vents

 

[Antsrcool]

altho my r12 79 cadillac would do that as well