A/C Fix You May NOt Need A New Compressor

coronan

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01 Golf
atmarine:
It can be done in the car but its much easier to keep things clean out of the car.
Also you need to remove the compressor to drain the oil.
 

DanG144

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If you want to drain the oil, you need to remove the compressor.

I generally clean the compressor and and engine at a car wash, then finish cleaning it with brake cleaner and a brush, then pull the compressor head, off, leaving the hoses attached to the head. Pry out the reed valve pack, which is held together with the RCV. Then replace the RCV. Reinstall the head, change the drier.
 

DanG144

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Coronan,
You need to check out your fans. Make sure they are good. You have more than one problem, one with at least one bad fan, one with compressor control.

From your description, it could very well be that your compressor is cycling off on high pressure - 450 psi on high side. Running the compressor for a minute with no fans can get pressure pretty high.

I would check out and repair your fans, then troubleshoot more if required, using this thread. The PDF documents linked in the first post are where to start.

http://forums.tdiclub.com/showthread.php?t=242699 check your fans out
 

DanG144

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Coronan,
An easy way to tell how much the lack of fans is affecting you, and see if you may have HP sensor issues as well, is to take a strong spray from a garden hose (choose a spray pattern that puts out a lot of water over a large area of the condenser coils) and keep the condenser coil sprayed down. Move the spray to keep flow all over the coil.

But you have to fix the fans...
 

atmarine

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'99 Golf 5 speed
Bad compressor-for real

Tonight I went about replacing my RCV. When I got the compressor apart and on the bench 2 discharge valves have discentegrated and scored up several pistons. An RCV fix is not going to help this one!

When replacing the compressor which one to to with? I have ruled out anything autozone due to previous experiences of colleagues. IDParts has a Valeo for $279, or a Sanden for $369. Any preference or experience with the Valeo?

There was a very small amount of debris in the discharge hose. I am going to flush out the condenser with liberal amounts of brake klean and compressed air. I pulled the expansion valve and it was spotless so I was not going to flush out the evap. I will also replace the drier at the same time and any O rings I disassembled. Anything else further I should know or do?
 

DanG144

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I don't have any experience with the Valeo.
I do know that Peter of IDParts will not knowingly sell poor parts.
But I have no idea of the comparative worth of the compressors.

So you are flushing the hoses as well, right? At the least, the hose from the compressor to the condenser, and the suction hose. Metal bits often find their way against the flow and up the suction hose when the compressor is shutdown.
 

atmarine

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How much oil for new compressor

I am about to install a new Sanden compressor on my MKIV. I will also be flushing the condenser, evap, and lines at the same time. The new Sanden compressor comes "pre-charged" with oil and ready for install.

My question is, is the oil in the new compressor adequate for the entire system, or do I need to add more oil? I will be using PAG 46 oil.

Thanks all!
 

UhOh

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I am about to install a new Sanden compressor on my MKIV. I will also be flushing the condenser, evap, and lines at the same time. The new Sanden compressor comes "pre-charged" with oil and ready for install.

My question is, is the oil in the new compressor adequate for the entire system, or do I need to add more oil? I will be using PAG 46 oil.

Thanks all!
If you replace the drier then you need to add oil. There's amounts specified somewhere around here (DanG144 can probably tell you off the top of your head).
 

DanG144

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Actually the new compressors normally come with all the oil you need for a flushed (oil free) system.
So quite often, if you are putting them on a system that has not been flushed and made oil free, you need to remove a little oil from them.
If you replace the drier on a non-flushed system, you may want to put about 14cc of oil in it.

135-150 cc total.
compressor 50%
condenser 10%
suction line 10%
discharge line 000
evaporator 20%
receiver drier 10%

As I said on a flushed system you would want 135 to 150 cc of oil in your compressor before you charge it - all the oil in the compressor. It will naturally spread through the system.
 

Drewmeister

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Texas
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2004 Jetta TDI
I think this might be my problem, but I'm not sure. My A/C is blowing cool but not cold enough, especially now that it's getting hot. When the A/C is on, the A/C clutch is engaged continuously, with no slippage of clutch or belt, and both fans are operational. The high-side pressure is definitely too low; low-side pressure is in the ballpark but may be a bit off from where it should be. I also noticed the "pressure transferring/equalizing" noise (from the evaporator/expansion valve area, passenger side of dash) I hear when the A/C is first turned on is noticeably louder than it used to be.

At 87F ambient, the pressure is 31 low/130 high, and 95 psi with the A/C off (after both sides equalize). A couple weeks ago, at 76F ambient, it was 32 low/105 high; 75 off. The pressure when off seems close to the vapor pressure charts for R-134a, if perhaps slightly low, so I don't think the problem is low refrigerant, but I'm not sure.

Does this sound like a refrigerant control valve problem?
 
Last edited:

Bengoshi2000

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I think this might be my problem, but I'm not sure. My A/C is blowing cool but not cold enough, especially now that it's getting hot. When the A/C is on, the A/C clutch is engaged continuously, with no slippage of clutch or belt, and both fans are operational. The high-side pressure is definitely too low; low-side pressure is in the ballpark but may be a bit off from where it should be. I also noticed the "pressure transferring/equalizing" noise (from the evaporator/expansion valve area, passenger side of dash) I hear when the A/C is first turned on is noticeably louder than it used to be.

At 87F ambient, the pressure is 31 low/130 high, and 95 psi with the A/C off (after both sides equalize). A couple weeks ago, at 76F ambient, it was 32 low/105 high; 75 off. The pressure when off seems close to the vapor pressure charts for R-134a, if perhaps slightly low, so I don't think the problem is low refrigerant, but I'm not sure.

Does this sound like a refrigerant control valve problem?
I don't *think* it's an RCV problem, mainly because your low side figures look correct. Your high side is low, imo. At 87F Ambient, high should be close to 191. I guess it is entirely possible that you are at the very front end of RCV failure.

My understanding of RCV failure is that the low and high pressure sides will increase and drop respectively. The low on my car was 57 and high was 80. I replaced the RCV and seals (and filter/drier) this weekend and now I'm hitting 31 and 195 with 38F at the vent at 2000rpm.

If I'm wrong on any of this, I welcome being corrected.

You may want to check the forums at ackits.com, lots of good reading there.
 

DanG144

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Ben is absolutely correct.

Drew, I would recharge the unit with refrigerant. Your numbers show you have SOME liquid refrigerant present, but it cannot say how much.

Something is preventing good heat transfer.
1) Low charge.
2) Bad Thermal Control Valve (at the firewall, engine side.) This jives with more throttling noise. I would splurge for a new OEM one - many of the aftermarket ones are pretty iffy.
3) Bad air flow - foam gone from the air doors or dampers inside the HVAC unit. Ever see foam come out of the vents? I saw my first bit a week ago. This lets the air simply bypass the evaporator coil, so it does not cool as is should. The AC side sees a low load.
3)
 

Genesis

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If you haven't fixed the blend doors on the car I virtually guarantee that, given the age of these vehicles, the foam is gone. It's a bear of a job but not impossible to do without removing the dash.
 

Drewmeister

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Texas
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2004 Jetta TDI
I repaired the blend doors when I replaced the heater core last year, so it's not that. Because I have the single-piece HVAC box (vs. the split box) I had to discharge the A/C and remove the whole box to do the heater core. I also cleaned the evaporator at that time, which had a little bit of dust & mold accumulation near the bottom. Afterwards I vacuumed down the system and recharged by weight (granted, using a kitchen scale to weigh A/C cans with the hose attached isn't 100% reliable, but I tried). The A/C worked great (better than before, thanks to the blend door repair) all summer and fall and the randomly warm "winter" days we get -- really until it started getting hot this spring.

I looked for leaks with a black light but the only place I could see glowing oil was in the service valves (which I'd just connected the gauges to). I guess it is possible they are leaking (or were, and are now properly seated, since after cleaning them out with a Q-tip I didn't see any more oil).

I had a little bit of refrigerant left over (exactly 50 g, it turns out) so I added it to see if it would help. It did stabilize the low side at 32 (this was the first time I checked pressures, when it was 76F ambient) whereas before it was going back and forth between 31-35, but didn't affect high side pressure.

I kinda hope it isn't the expansion valve because one of the screws holding that on is corroded and stripped out, so it probably means taking out the evaporator (and the whole dash, of course) to repair that. At first I'd thought I had to remove it from the evaporator to take out the HVAC box, before discovering that the hole in the firewall was big enough for it to fit through, and got the top screw out but the bottom one just stripped the Allen head. With the box out I attempted to break it loose by cutting a slot in the head with a dremel and using a large flat screwdriver, but no such luck, so I just put the other screw back in and left it alone.

The Bentley manual's troubleshooting chart seemed to indicate compressor fault for low side normal/high side low state. I forget what the indicators of expansion valve fault were but I don't think it was this. Of course, I've learned to take that manual with a grain of salt...
 

Keith63

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Finally after almost two (2) years of only getting my ac to 60 degrees in any ambient temp, I replaced the RCV. It took me the better part of the day, but now I am blowing out cold 38 degree ac. I had to evacuate the system, replace the RCV, then pull a vacuum, refill with a little pag and 134a, and now I am good to go, for under $100.00. Sure beats paying almost $1,600.00 at the dealer for a new compressor, which I didn't need. Thank goodness for this TDI forum!
 

Aggie88

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May 22, 2017
Location
McKinney, Texas
TDI
2006 TDI New Beetle
RCV, Compressor, or Expansion Valve

First post after trolling and learning how to fix the NB for years. Beetle is now in my daughter's possession and was informed upon her return from college the A/C isn't cold. Of course, TDIclub forums are the first place to look and found DanG144's post on the fans. Both fans exhibited the low speed failure. Fixed that with the help of the .pdf - BTW, my fans didn't have a resistor, but instead had a resistive element that didn't fail, but the high speed wire had burnt itself in half going to the element. Anyway, A/C still doesn't work. My low/high pressures with A/C on are 70/120. With the A/C off, the pressures don't equalize and go to 350+/150. So, with those pressures and not equalizing, is that the RCV, Compressor, or Expansion Valve. IDparts is having a 10% sale, so it's financially reasonable to replace compressor, drier, and expansion valve all at once. Bug has 153K, so I'm thinking it's time to replace it all anyway.
Any experienced guidance is appreciated.
 

Genesis

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Sevier County TN
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'03 Jetta Wagon
RCV likely but you won't know until you take the compressor apart.

Here's the problem with just buying one -- if you find it's grenaded internally YOU NEED TO CHANGE EVERYTHING, and it's a ***** to do since you have to rip the dash out to get to the evaporator. If you don't ONE BIT of metal that's in there and finds its way back to the new compressor will destroy it.

For this reason above all others I'd pull the compressor and IF the internals are ok change the RCV. It's ~100 worth of parts AND if that's all that's wrong you win big. If the compressor shows signs of internal damage then you're into this for an evaporator, condenser, lines and expansion valve plus the compressor (plus of course the dryer) -- and a hell of lot of work to change it all.
 

DanG144

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First post after trolling and learning how to fix the NB for years. Beetle is now in my daughter's possession and was informed upon her return from college the A/C isn't cold. Of course, TDIclub forums are the first place to look and found DanG144's post on the fans. Both fans exhibited the low speed failure. Fixed that with the help of the .pdf - BTW, my fans didn't have a resistor, but instead had a resistive element that didn't fail, but the high speed wire had burnt itself in half going to the element. Anyway, A/C still doesn't work. My low/high pressures with A/C on are 70/120. With the A/C off, the pressures don't equalize and go to 350+/150. So, with those pressures and not equalizing, is that the RCV, Compressor, or Expansion Valve. IDparts is having a 10% sale, so it's financially reasonable to replace compressor, drier, and expansion valve all at once. Bug has 153K, so I'm thinking it's time to replace it all anyway.
Any experienced guidance is appreciated.
Gig'em Aggies.
It sounds to me as if your gauges are not communicating with the high side. This is fairly common with the VW and the gauge sets I have used. Open the equalization (cross-connect) valve momentarily to alter the gauge reading. verify that it changes.
If it does not change after shutdown, then you almost certainly have this issue - because pressure in the system WILL change.

I would think, based on your 70 psi suction (low side) reading, that you do have the RCV issue.
 

Aggie88

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Good advice. I opened the valve after shut down and the pressures equalized around 90 psi. Does that point to bad RCV?
 

DanG144

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What points to a bad RCV is that the suction pressure would not go below 70 - it should be 35 or less. This also usually results in a lower high side pressure as well, around 120 is not abnormal for a bad RCV. However, I do not believe your high side pressure reading, as it seemed to be unchanging.

I would replace the RCV, if it were mine.
 

Drewmeister

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2004 Jetta TDI
Update on my situation: I added about 9 oz of R134a to the system 3 weeks ago; as I gradually added refrigerant, the high side pressure rose, but the low side stayed about the same. I stopped when the high-side pressure reached 150 (ambient was in the upper 70s F, IIRC). The A/C has worked great ever since, even on 90-degree days like today.

It seems like either there's a very slow "takes all winter" leak or, hopefully, it was a speck of dirt in a service valve which has since dislodged itself. When I first put the gauges on about a month ago I did notice a little bit of bubbling in the high-side valve after disconnecting them; this lasted a few seconds. On the more recent times I've connected gauges, this has not happened. Either way, glad I didn't do any unnecessary repairs!

Thanks and Gig 'Em!
 

3turboz

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Tempe AZ USA
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2000 Golf GL Wolfsberg
I have read this entire thread today as well as others.

AC has been getting warmer for a few days and pressures are a bit wonky, but not near equal. Low side is a too high (50) and high side was 200. Both fans working fine.

So I am thinking either the clutch is slipping, the RCV is bad, or the expansion valve is stuck wide open.

My real question is whether it is worth trying the RCV on a 230,000 mile compressor or if it is best to spend a couple hundred more on a new compressor. How long can one last?

I am thinking it might be like when I put a regulator and brushes in my Alternator and got another year out of it, but then the bearings went out.
 

KrashDH

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Washington
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I have read this entire thread today as well as others.

AC has been getting warmer for a few days and pressures are a bit wonky, but not near equal. Low side is a too high (50) and high side was 200. Both fans working fine.

So I am thinking either the clutch is slipping, the RCV is bad, or the expansion valve is stuck wide open.

My real question is whether it is worth trying the RCV on a 230,000 mile compressor or if it is best to spend a couple hundred more on a new compressor. How long can one last?

I am thinking it might be like when I put a regulator and brushes in my Alternator and got another year out of it, but then the bearings went out.
I am going through this situation as well.
All of the tests for me have passed. Finally broke down and I ordered a new RCV, gasket kit, TXV, drier, and all of the o rings. Took me probably 2 hours to get everything in the A/C system out, as well as take the old oil pan off (I'm swapping to a hybrid while the compressor is out of there and there is room). The drier was by far the hardest thing for me to get out. I'm waiting on parts.

I think it's worth replacing parts on these compressors. The couple hundred on a new compressor likely isn't going to be "new", especially OEM and will likely be something re-built. I think I got everything for around $100.

You can open up the back end of the compressor easily too once it out and look at the guts of it. That can also help you determine whether to go new or not. Under most circumstances the internals will still be pristine
 

3turboz

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I did say "a couple hundred more" (than the RCV fix) but that is not entirely correct as the compressor alone is $330, plus I would change the exp valve, drier, flush solvent, etc. I am sure I would be up to $450 by the time I was done.

The car started leaking coolant from what I can only surmise is the water pump about the same time. Been 82K miles since I did timing belt and all that, so time to do another major service.

So, my plan now is to take the comp off and examine it. If all looks clean I will order the RCV parts and hopefully have the TB service done by the time the parts show up.
 

3turboz

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Thanks to those who contributed to this thread. I did the RCV fix this weekend and it is working well. Here is my contribution:

DO NOT torque the head bolts to the spec in the Sanden manual! It calls for a step at 14 ft lbs and a finish at 24-27 ft lbs. I can tell you that they will hold 14, but not much more.
 

KrashDH

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Thanks to those who contributed to this thread. I did the RCV fix this weekend and it is working well. Here is my contribution:

DO NOT torque the head bolts to the spec in the Sanden manual! It calls for a step at 14 ft lbs and a finish at 24-27 ft lbs. I can tell you that they will hold 14, but not much more.
This is a very good point. I also ran into the 24-27 ft-lb that the manual said...and I snapped a head bolt! I went back through the manual. At the beginning, they list 2 different bolt sizes...M6 and M8. The M8 bolts are supposed to be torqued to the 24-27, the M6 bolts are 10 ft-lb (which our compressors have)! Unfortunately in the manual, where it shows the procedure to close the compressor back up, it uses the 24-27 and doesn't list the M6 size torque. I was lucky that one of my local hardware stores actually carried that size and style of bolt so I just replaced them all.
 

3turboz

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This is a very good point. I also ran into the 24-27 ft-lb that the manual said...and I snapped a head bolt! I went back through the manual. At the beginning, they list 2 different bolt sizes...M6 and M8. The M8 bolts are supposed to be torqued to the 24-27, the M6 bolts are 10 ft-lb (which our compressors have)! Unfortunately in the manual, where it shows the procedure to close the compressor back up, it uses the 24-27 and doesn't list the M6 size torque. I was lucky that one of my local hardware stores actually carried that size and style of bolt so I just replaced them all.
Thanks for the clarification. I snapped one off as well, but at this time am running one short. I am sure I stretched the others, so I will schedule a time to replace them all.
 

KrashDH

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Washington
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Thanks for the clarification. I snapped one off as well, but at this time am running one short. I am sure I stretched the others, so I will schedule a time to replace them all.
You should be fine with the old bolts and 1 new one, but if you want the peace of mind replace them if you want. The reason I say this as the OEM bolts are hardened. They have a high tensile strength but VERY little elongation before failure. Ie they will just snap and not neck down/yield before failure. I inspected all my old ones and there is no noticeable elongation or yield. I actually re-used 1 of my old ones because I bought 6 instead of the 7 needed.:cool:
 
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