Check your radiator/condenser fan operation NOW

Leadbettr

Member
Joined
May 20, 2022
Location
Tucson
TDI
Golf 03 TDI
Age, or someone recharged the unit after a complete loss of pressure without purging and replacing the drier -- in which case you have acid damage everywhere and more trouble to come.
I'll vacuum and replace the drier. But can I clean/flush the system like you can in the coolent system?
 

Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
Realistically, no. You can flush everything but the compressor, but you need the proper stuff to do it, and trying to improvise that is a bad idea because you have to get absolutely EVERYTHING out. Anything that does not evaporate fully under hard vacuum is serious trouble.

About all you can do without replacing the entire system is change the condenser core, purge the system with either very dry air (e.g. scuba air) or nitrogen, install the new drier and IMMEDIATELY pull hard vacuum, then recharge with the correct amount of added oil (for the replaced components, in this case the condenser and drier.) The drier must NOT be allowed to be uncapped and exposed to atmosphere until you are prepared to basically immediately draw hard vacuum on it as it will absorb water vapor from the atmosphere and once it does its "consumed" and worthless.
 

Leadbettr

Member
Joined
May 20, 2022
Location
Tucson
TDI
Golf 03 TDI
Realistically, no. You can flush everything but the compressor, but you need the proper stuff to do it, and trying to improvise that is a bad idea because you have to get absolutely EVERYTHING out. Anything that does not evaporate fully under hard vacuum is serious trouble.

About all you can do without replacing the entire system is change the condenser core, purge the system with either very dry air (e.g. scuba air) or nitrogen, install the new drier and IMMEDIATELY pull hard vacuum, then recharge with the correct amount of added oil (for the replaced components, in this case the condenser and drier.) The drier must NOT be allowed to be uncapped and exposed to atmosphere until you are prepared to basically immediately draw hard vacuum on it as it will absorb water vapor from the atmosphere and once it does its "consumed" and worthless.
Great advice thanks. Where can I find Nitrogen or an adapter for a scuba tank fitting? I haven't seen that anywhere.
On a side note, I would haven loved to have bought a can of nitrogen with added dye to find my leak.
 

Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
A "blow fitting" for the LP hose works; they're available. Scuba air is dry to -50F dewpoint, approximately as dry as nitrogen from a gas supplier. I had an Airgas account for a long time so I could go pick up whatever, but since I also had a dive compressor with a hyperfilter on it (which is about as clean as it gets, and it has to be because otherwise partial-pressure blending with the output is asking for a "boom!") that was the easy answer. Detach both hoses at the compressor and clear it out. A LP hose on a dive reg is typically set to ~120psi maximum.

Just do not put the new drier on until you are prepared to pull vacuum; it is very, very important that it NOT become saturated or it won't do anything and moisture in the system combines with the refrigerant and oil over time to produce an acid, which then eats EVERYTHING.
 

SilverGhost

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Mar 25, 2005
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Back in So Flo - St Lucie
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'05 Golf - totaled :(, wife's '13 Beetle - buy back, TDIless
Volkswagen has a TSB on how to flush the Freon system (87-18-06). Have to put a bypass in for the expansion valve - we have case of brass bypass blocks, but you can gut an old expansion valve for the job. If the drier is external then we put in a jumper hose to remove it from the circuit. If it is built in (such as any of the new cars) leave it in then replace after flushing. Disconnect compressor and install adaptors on pipes at compressor, reverse flush system . Can by either nitrogen or Freon, but have better results with Freon. We have a filter box that screens out, then filters the rest of the Freon as it is recovered.

Before we got an updated AC service station we used brake clean to get the large chunks of junk out, then followed up with Nitrogen to clean that up.

Either case new drier went in last and IMMEDIATELY pulled hard vacuum for over a hour. Any remaining moisture would be boiled off and system was as clean as possible.

Jason
 

Rinderle_77

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Joined
May 29, 2018
Location
GJ, CO
TDI
2000 Beetle TDI, 2015 Audi Q7 3.0TDI
May be the wrong thread to ask in, but here goes. '00 NB, everything in the AC system seems to meet spec. Voltages, resistance on clutch coil, pressures, etc. BUT... the compressor just shuts off at random. Everything works perfect for a few days, then compressor won't engage for a few days. Then, randomly, it will begin to work again. I feel it has got to be the clutch coil failing, but every time I check it, it tests good.
 

Nuje

Top Post Dawg
Joined
Feb 11, 2005
Location
Island near Vancouver
TDI
2015 Sportwagen; Golf GLS 2002 (swap from 2L gas); 2016 A3 e-tron
So, when we say "immediately", how much time is that?
I had so much trouble getting my dryer bolted in, it had to have been open for over an hour (which I'm guessing is way too long).

How long is reasonable?
 

SilverGhost

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Mar 25, 2005
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Back in So Flo - St Lucie
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'05 Golf - totaled :(, wife's '13 Beetle - buy back, TDIless
So, when we say "immediately", how much time is that?
I had so much trouble getting my dryer bolted in, it had to have been open for over an hour (which I'm guessing is way too long).

How long is reasonable?
The 30 seconds between popping the cap(seal plug) off and putting the AC line in.

Jason
 

Nuje

Top Post Dawg
Joined
Feb 11, 2005
Location
Island near Vancouver
TDI
2015 Sportwagen; Golf GLS 2002 (swap from 2L gas); 2016 A3 e-tron
Ok. So, twice now, I've had the A/C system in for "flush, check for leaks, and re-charge". And both times, it leaves the dealership with the A/C system blowing icy-cold air. A few days later, it's "cool" air....and within a week or so, I have nothing - no fans, no pressure in the system.
(Backing up a bit, I got the car with non-functioning A/C; doing a 2L gas --> ALH swap, I disconnected everything and replaced the line from the firewall to compressor, as well as dryer (new) and condenser (used).

First time it was a bad o-ring - I'd replaced the dryer and as mentioned above, the re-attachment process did not go smoothly and ended up pinching the o-ring.

So, back it went to VW where the tech replaced o-rings any place there was dye leakage that was visible, pressure tested, pulled vacuum - both of which held as expected. And again, the system went from perfect function (super-cold) to "meh-cool", to nada and no refrigerant.

So...
what's the next step? When the refrigerant is present, the system works (seemingly) perfectly. Where could I be losing it - no dye splotches after the second fill like there was after the first one, at any connection points or any refrigerant lines I can see in the engine compartment or on the condenser.

Even if the dryer was "dead", that wouldn't lead to loss of R134a, would it? I'm $700 into this at VW, so don't really want to go back for a re-charge until I know that the leak isn't leaking anymore.
 

03TDICommuter

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Dec 8, 2016
Location
So. Cal
TDI
01' NB, 5spd
Even if the dryer was "dead", that wouldn't lead to loss of R134a, would it? I'm $700 into this at VW, so don't really want to go back for a re-charge until I know that the leak isn't leaking anymore.
It's definitely leaking, and like Wonneber said, could be the evaporator. You wouldn't see dye except maybe in the the drain tube.

That said, a leak sniffer would go off like crazy, especially if you're leaking everything in a few weeks timeframe. Does the dealership only have dye for leak detection? (beside also monitoring vacuum). Refilling with a trace of refrigerant, and then the rest of it with nitrogen to 200 psi will show where it's leaking with a sniffer.
 

Nuje

Top Post Dawg
Joined
Feb 11, 2005
Location
Island near Vancouver
TDI
2015 Sportwagen; Golf GLS 2002 (swap from 2L gas); 2016 A3 e-tron
I was gonna say....please don't say "evaporator". 😱

But yeah - if it's going somewhere and we can't see where....that would seem to indicate that it's going where we can't see. 🤬
 

Nuje

Top Post Dawg
Joined
Feb 11, 2005
Location
Island near Vancouver
TDI
2015 Sportwagen; Golf GLS 2002 (swap from 2L gas); 2016 A3 e-tron
For the kids out there who want to see what you can see under a blacklight, here's what I saw (even more pronounced when looking through yellow-lens glasses) after the first go-round, with the crushed o-ring at the top of the dryer. You can see it running down the side of the dryer, and even splashed all the way out to the adjacent solid power steering line.

 

2nsane2005

Well-known member
Joined
Aug 29, 2010
Location
Edmonton
TDI
2001 Jetta Tdi Blue Lagoon
I tried the test mentioned. key on, ac button pushed and fan speed low and the fans DON'T spin. I powered the fans directly with 12volts and they spin high and low speed. I also powered the thermoswitch and both fans spin. I do know my ac system is low on refrigerant though. I think I read somewhere the test should work regardless of the refrigerant level?!
 

Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
If there is no charge in the system the fans will not come on, nor will the compressor. There is only one sensor (on the high side) and if the not-running pressure is under 30psi or so it will not engage. It also will lock out if the ECU thinks the outside air temperature is too cold (just above to below freezing.)
 

2nsane2005

Well-known member
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Aug 29, 2010
Location
Edmonton
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2001 Jetta Tdi Blue Lagoon
If there is no charge in the system the fans will not come on, nor will the compressor. There is only one sensor (on the high side) and if the not-running pressure is under 30psi or so it will not engage. It also will lock out if the ECU thinks the outside air temperature is too cold (just above to below freezing.)
Ok thanks for clearing that up !
 

braddies

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Joined
Jul 26, 2021
Location
America
TDI
03 golf ALH
Hey guys hoping this a good place for this question, got an 03 ALH with both fans running with the AC button, AC blows cold..

but at idle turning the AC on changes the motor sound a bit and I get a "pulsing" idle, where the idle varies in rpm a bit from 920-929 and the resonance in the cabin gets loud, almost like it's "hunting" to maintain idle.
As soon as the AC is turned off idle smooths out at a solid 925rpm (idle used to be at 906rpm but I used vcds to raise it a bit for a little less nvh)
Any insight as to why this surging idle happens? Normal with an ALH and I should be happy with cold air? Symptom of something else?
With the AC on there's a (somewhat) perceptible loss of power but it still pulls strong to redline. Thank you all for helping keep these cars going!
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Seems counterintuitive for an ALH, but maybe it's a tad low on current at idle. Try putting a long trickle charge on the battery. Check belt condition and tensioner condition. But yea, sounds more or less Normal.
 

P2B

Top Post Dawg
Joined
Jan 11, 2006
Location
Toronto & Muskoka, Canada
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2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
Doesn't sound normal to me. Turning the AC on at idle will cause a momentary dip in idle speed - that's how you can tell if the compressor is engaging without opening the hood - but the ECU should immediately compensate for the load increase and maintain the set speed.

I wonder if it's a side effect of adapting the idle speed. Does it still do it if you reset idle to stock?
 

braddies

Veteran Member
Joined
Jul 26, 2021
Location
America
TDI
03 golf ALH
Doesn't sound normal to me. Turning the AC on at idle will cause a momentary dip in idle speed - that's how you can tell if the compressor is engaging without opening the hood - but the ECU should immediately compensate for the load increase and maintain the set speed.

I wonder if it's a side effect of adapting the idle speed. Does it still do it if you reset idle to stock?
Was doing the same thing at 906rpm idle since the beginning of summer climate, 925 was a little less nvh at non AC idle.

When first turning on the AC in any fan position Definitely feel/see-on-scanguage a dip in rpm like a substantial load was put on the motor, followed by an increase in engine sound and a ramp-up in rpm, followed by a drop in engine load and sound and rpm, then a "wandering" idle searching around 925. Not sure how to graph this..
 
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BobnOH

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Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
We don't need the graph, your text explains it well.
But here is my favorite-
VAG-COM Plotting Software
Malone also has one you can use interactive on the interwebz.-
New Log Viewer (VCDS / VAG-COM or any Logging Too
Doesn't sound normal to me. Turning the AC on at idle will cause a momentary dip in idle speed - that's how you can tell if the compressor is engaging without opening the hood - but the ECU should immediately compensate for the load increase and maintain the set speed.

I wonder if it's a side effect of adapting the idle speed. Does it still do it if you reset idle to stock?
Well yes, not exactly normal, it depends on the degree of idle drop. I don't get concerned as long as the motor don't stall or hesitate to accelerate.
This is the first time I've read someone using Adaptation to increase idle speed. Often wondered if that would alleviate certain issues on older cars.
 

braddies

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Joined
Jul 26, 2021
Location
America
TDI
03 golf ALH
Thanks! It's still fine to drive daily just wondering if that slightly surgey idle with the AC on could be a symptom of something else, but the vents blow cold air and the nights are getting cooler so it's all good.
Looking at the tensioner there's almost no movement, no bouncing belt, so the alternator pulley is probably fine?
Dunno what nozzles are on it but was thinking of getting a callibrated new set as a matter of maintenance
 

braddies

Veteran Member
Joined
Jul 26, 2021
Location
America
TDI
03 golf ALH
Here is my favorite
VAG-COM Plotting Software
Malone also has one you can use interactive on the interwebz.-
New Log Viewer (VCDS / VAG-COM or any Logging Too
COOL! Thanks!
Well yes, not exactly normal, it depends on the degree of idle drop. I don't get concerned as long as the motor don't stall or hesitate to accelerate.
This is the first time I've read someone using Adaptation to increase idle speed. Often wondered if that would alleviate certain issues on older cars.
If I remember correctly lowering idle would make it run a little rougher while raising idle rpm smoothed it out, a little bit. Still runs great
 

sruchris

Veteran Member
Joined
Sep 14, 2009
Location
NE Ohio
TDI
2003 ALH Wagon
I have a 2003 TDI Wagon. When I have the key on, engine off, the AC button on and the blower on 1, neither radiator fan comes on. The fans are good. They both come on when I pull Fuse 16 in the cabin fuse box. The compressor was replaced 10k miles ago. I replaced the fan control module today. I loosened the two screws, crawled under the car, unplugged the old oem one and plugged in my new Amazon Chinese one. Before bolting the new one down, I turned the key on, AC on and fan to 1, and both fans turned on! Yeah!

I then started the car and saw the compressor turning, so I thought I fixed my AC. I then turned the car off, oriented the new fcm into its home, and bolted it down. I then checked the fans again and, this time, the fans don't come on. I swapped the old one back in, and the new one back in several times and I cannot get the fans to turn on. Am I missing something? All three 30A green fuses on top of the battery are good.
 

Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
If the pressure is insufficient in the system the fans will not come on. You may have basically nothing in there (and when it gets a bit warmer then its "hot enough" and starts)
 

sruchris

Veteran Member
Joined
Sep 14, 2009
Location
NE Ohio
TDI
2003 ALH Wagon
If the pressure is insufficient in the system the fans will not come on. You may have basically nothing in there (and when it gets a bit warmer then its "hot enough" and starts)
That's what I was thinking. The engine was warm when the fans initially turned on and cooled off by the time I finally got the right FCM bolt lined up and in.
 
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Genesis

Top Post Dawg
Joined
Feb 26, 2003
Location
Sevier County TN
TDI
'03 Jetta Wagon
It is quite close to empty if the fans will not run (the compressor also will not pull in if this is the case.) Assuming you have gauges and such to fill with you could subtract perhaps 20% from the fill spec and I bet you'd be "close enough" (and not going to exceed the charge level; overcharging is a very bad idea.) Of course the underlying issue is that you have a leak, so that need to be found as well. Got a UV light (the refrigerant usually has a UV dye in it to help find said leaks) but to fix it you have to evacuate the system, fix it and then replace the dryer and pull a hard vacuum before recharging. Since its illegal to deliberately vent refrigerant this means you either need a shop that can do that or the proper equipment to do so.
 

P2B

Top Post Dawg
Joined
Jan 11, 2006
Location
Toronto & Muskoka, Canada
TDI
2002 Jetta, 2003 Jetta, 2003 Jetta Wagon
I had a similar issue that turned out to be one of the heavy red power wires to the FCM was not properly crimped to the connector pin during manufacturing.

At first I re-plugged the FCM connectors and the fans started running, didn't find the real issue until it failed again a few days later.
 

Gothmolly

Veteran Member
Joined
Feb 3, 2005
Location
Providence, RI
TDI
2002 Golf
Does anyone know if there is an AC delete option? Some kind of pulley which can be installed to keep the right belts in the right tensions? At this point the AC fix will cost more than the car is worth (counting time and money).
 
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