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Discussion Starter #1
A/C not "that" cold anymore. Bad expansion valve? Pressure readings/diagnose issues!

Guys,

The weather down here in a JOKE, it's something like 40ºC by midday (105 ºF). Only now I'm realizing how weak my A/C system performs, I can't get that nice iceberg breeze from the vents as before, only a "cool" breeze although the compressor kicks in as it should. VCDS Lite shows no codes at all so I took the car to an A/C shop and these are the readings from the system's pressure:



According to the guy, my left side readings (blue gauge) are supposed to be higher than that, around 40 psi (green circle) instead of the current 29 (in red dots):

He couldn't find anything wrong with the system, only these low-pressure readings that according to him were supposed to be higher than this. He is suggesting me to replace the A/C expansion valve which looks like this:



I'd like to hear your comments about these readings and from his approach as A/C is something that know absolutely nothing. I'm supposed to return to the shop in a couple of hours to replace the valve, you think it's worth it?

Thanks!!
 

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Discussion Starter #2
Err.. sorry for the fake reply but the Edge browser is not allowing me to edit my post (the text window get's blank and everything I had typed was gone)

Something that might be worth mentioning, ambient temperature during those pressure readings were around 36ºC (97ºF).

Thanks!
 

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The variable displacement compressor makes things a little bit different than a regular a/c system. You can't always go by the pressures because the compressor keeps the low pressure the same all the time by varying the displacement of the compressor.

There are 3 tests to try from the service manual to diagnose a/c performance.

Test conditions
 A/C refrigerant system fully charged; discharge, evacuate and recharge system if necessary
 Condenser and radiator clean and free of obstructions (spray clean if necessary)
 Air distribution can be adjusted correctly using control knobs (all air distribution flaps reach end
positions)
 Wiring OK per wiring diagram
 Outside (ambient) air temperature between 20-30 ° C (68-86 ° F)
 Drive belts for A/C compressor and Generator in good condition and properly tensioned

Test 1: Air temperature drop from center instrument panel outlet, checking (A/C system cooling performance)
 Start engine.
 Set temperature control to maximum "cold" (if Manual A/C) or "LO" (if Climatronic).
 Manual A/C: press "A/C" button and select second blower speed.
 Climatronic: Select minimum blower speed (manual override) by pressing "decrease blower speed"
2003 Volkswagen Passat
HVAC Heating, Ventilation Air Conditioning
button (observe front "blower speed" display in control head).
 Adjust air distribution to instrument panel outlets.
 Insert thermometer into center instrument panel outlet and raise engine speed to approximately 1500
RPM.
Specified result
With humidity normal and outside (ambient) temperature between 20-25 ° C (68-77 ° F), system is cooling
satisfactorily if air temperature from center instrument panel vent drops below 10 ° C (50 ° F) within 1 minute.
For higher ambient temperatures and/or higher humidity, specified air temperature from center instrument panel
vent can be slightly higher.
If specified reading is not obtained, perform tests 2 and 3, then compare results of all three tests --> table,
SYSTEM PRESSURE TESTING.

Test 2: A/C system high pressure, checking
 Connect high- and low-pressure hoses of refrigerant recovery/ recycling/recharging unit Kent-Moore
ACR 4 or equivalent, to high- and low-pressure service valves.
 Disconnect electrical connector from coolant fan.
 Start engine.
 Set temperature control to maximum "hot" (if Manual A/C) or "HI" (if Climatronic).
 Manual A/C: press "A/C" button and select highest blower speed.
 Adjust air distribution to footwell outlets.
 Raise engine speed to approximately 1500 RPM.
Specified result
System high pressure is normal if high-pressure gauge reads 232 psi (16 bar) within 30 seconds.

Test 3: A/C system low pressure, checking
 Connect high- and low-pressure hoses of refrigerant recovery/recycling/recharging unit Kent-Moore ACR
4 , or equivalent, to high- and low-pressure service valves.
 Start engine.
 Set temperature control to maximum "cold" (if Manual A/C) or "LO" (if Climatronic).
 Manual A/C: press "A/C" button and select first blower speed.
 Climatronic: Reduce blower speed to lowest setting (manual override) by pressing "decrease blower
2003 Volkswagen Passat
HVAC Heating, Ventilation Air Conditioning
speed" button (observe front "blower speed" display in control head).
 Adjust air distribution to instrument panel outlets.
 Raise engine speed to 1500 RPM.
Specified result
System low pressure is normal if low-pressure gauge reads 22-36 psi (1.5-2.5 bar) within 30 seconds.
 

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I'm interested to see if you see an improvement by replacing that part. I'm having the same issue as you describe. I haven't taken it to a shop to get looked at yet, though. I was thinking the expansion valve, or the receiver/drier was my problem.
 

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Discussion Starter #7
I'm interested to see if you see an improvement by replacing that part. I'm having the same issue as you describe. I haven't taken it to a shop to get looked at yet, though. I was thinking the expansion valve, or the receiver/drier was my problem.
Holly COW, that thing is COLD!

So, continuing from my previous episode.

After getting back to the shop, before plugging the gauges, he noticed something that according to him he hadn't noticed before and could be a symptom of low charge: the metal pipe next to the plug was full of ice around it, like an ice cream coating.

Now, according to what he said, old school knowledge says that whenever the pipes downstream from the gas expansion valve builds ice around them, that's an obvious indicate that the system needs more A/C fluid. I couldn't get the logics behind that and asked him about the expansion valve he mentioned before that could be the culprit. He told me that by then he hadn't realized how much ice was around that area and that messing around with the expansion valve might not be that wise as he only had aftermarket replacements and OEM ones are not available on BR dealers very easily ($$$). P.S.: He's is right on that, retail price on BR dealers is US$ 100 per valve!

Taking that in mind, I agreed to let the expansion valve alone and give the system an extra fill of fluid. After this fill, the compressor kicked in almost immediately all the ice around the metal pipe disappeared like magic. The A/C vents were blowing an extremely cold breeze (couldn't get the temperature readings by then) and the final pressure from the system looked much like before except that NOW I have cold air:



I do know that the high pressure reading were wayyyy beyond the limit posted above (232 psi) but the car was sitting under sun shine on a 40ºC ambient temperature and revving up from 1,500 to 2,000 RPM for almost 30 min so I won't bother.

So this all happened two days ago. Yesterday I took the car for a ride and the A/C was still running strong so I think I'll call it done.

As always happens with this car, whenever I fix something I realize something else needs repair so my next adventure will be locating this stupid black cap as mine was completely broken/cracked and won't fit into the plug hole no more:



If the A/C turns down on me again, I'll be back to update this thread!
 

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Discussion Starter #8
The problem is back!

Today I took the car back to the shop, I'm also feeling a strong smell of "something like gas" inside the car. Yadda yadda yadda, my evaporator is leaking. I've been googling around to find some replacements and came across parts manufactured by Air Products, REIN and Behr.

Since I'm taking the whole HVAC out I'll also replace the heater core which had been by-passed a long long time ago. The heater cores brands available are Auradia, Dansk, Meyle and FEBI.

From of all of those, the most expensive ones are from Meyle (heater core) and from Behr (evaporator). I'd like to hear from you more info about these parts as I'm not willing to go cheap with parts that are a NIGHTMARE to replace.



I'm really confused about the price difference between REIN/Behr evaporators and the Meyle/FEBI heater cores. Any insights? :(
 

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Niiice.

I've always used Valeo heater cores when I could find them. I'd think the Meyle/Febi core would be a better choice, but inspect both carefully if you have the opportunity to do so before buying.
 

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Discussion Starter #10 (Edited)
Niiice.

I've always used Valeo heater cores when I could find them. I'd think the Meyle/Febi core would be a better choice, but inspect both carefully if you have the opportunity to do so before buying.
Thanks! Unfortuately I dont have access to any of them. I ve seen some bad things about the Meyle heater core so Im almost picking the FEBI one.

Any suggestions on the evaporator?

EDIT: This is my current shopping cart. I'm planning to make the checkout by tomorrow! Still opened for suggestions. From what I've searched, BEHR seems to be more reliable than REIN for the evaporator. On the other hand, I'm picking FEBI for the heater core even if the Mayle costs more. I found one dude on the web complaining on the build quality from the Mayle heater core :(

I'm also adding this O-ring set, just in case (...)

 

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Rein parts are manufactured in the US. Behr - unless they're manufactured in the EU, they could be as worthless as "replacement" brand parts (made in China).
Febi started to manufacture its line of parts in China several YEARS back. People make their own choices based on the wallet, name sound, vicarious tales, etc. If the wallet/budget isn't an issue, then I would go w/ parts from a specialized VW parts site like Jim Ellis, 1stvwparts, vwpartscenter.net. I personally stayed away from Febi, but personal preferences differ from individual to individual. When manufacturing en-masse for a warehouse-type company feeding hundreds of vendors of aftermarket parts, the Chinese can screw royally. No ISO would prevent that. On the other hand, I just purchased a replacement upper radiator hose (Rein) for my V6 and the segment connecting into the radiator is shorter than the OE one. I cannot trust anyone anymore, hence I go for a balance buget-quality (if possible)
I would look at RM European- decent prices/OE parts (no bull)
good luck
 

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Discussion Starter #13 (Edited)
Hey thanks for the tips! You think "Air Products" would be more reliable than FEBI or Behr? I've got lots of parts from these brands already (expansion tank, rubber mounts, etc) and never had any issues.

You're saying "Air Products" >>>> FEBI/REIN/BEHR ? :confused:

EDIT: Checking the sites you've mentioned. I can't afford them. US$ 310 per part, just not happening. I gotta choose between the brands I named above: REIN, BEHR, Mayle and FEBI. :(
 

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Sorry for not checking the thread last night but I was tired.
http://airproductsgroup.com/index.html]Air Products [/url] seems to be a company specializing in A/C automotive parts, you be the judge. I would trust the ISO of an American company before any other's outsourcing to China. The price is 1/2 of the Behr's, but probably Behr is the best your money can buy,.
I purchased in the past from a CARQUEST store a Febi heater core for my C4Audi A6 and both the outlets were longer than they should have been. The heater core would not fit in the housing. I returned it and purchased instead a Meyle online (can't remember from where exactly, either AutohausAZ or FCP). That one was perfect, and it is still in the car after 5 yrs probably. I probably still have the photos on Photobucket...
That doesn't mean it would happen to you, but I personally never buy Febi parts ever since. It is your money, and your car.
Good luck
 

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The price is 1/2 of the Behr's, but probably Behr is the best your money can buy.
So BEHR is the one I'm picking. DONE!

I purchased in the past from a CARQUEST store a Febi heater core for my C4Audi A6 and both the outlets were longer than they should have been. The heater core would not fit in the housing. I returned it and purchased instead a Meyle online (can't remember from where exactly, either AutohausAZ or FCP). That one was perfect, and it is still in the car after 5 yrs probably. I probably still have the photos on Photobucket...
Man, THANKS A LOT for that insight. I'll stay way from the FEBI heater core and stick with the Behr evaporator. I'll replace the FEBI heater core by the Meyle one on the cart.

All this stuff gotta be imported, so I have to make it right from the beginning as "Returning them to the shop" is not an option on this situation :(
 

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All right then, order placed!



chefro, the MEYLE picture would not load but I picked it up instead of the FEBI heater core.

TO BE CONTINUED...

EDIT: Instead of picking the whole O-Ring set I tracked down all the O-Rings needed on ETKA (2 between the drier, one before the orifice tube and two between the HVAC and the hard lines) and ordered them one-by-one.

 

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Since you are going to open up the system, consider also getting replacement stems and orings for the two port valves, and maybe a new high pressure switch.

Ask them to do a UV dye test before they evacuate it down. You can get PAG oil with UV dye in it.

This is a great thread on AC.
 
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