AC not cold enough, expansion valve?

IDoSeaDoo

Veteran Member
Joined
Apr 13, 2011
Location
Raleigh, NC
TDI
2011 Jetta, CJAA 6spd
This season, I put gauges on the jetta and added some Freon to it. Pressure is about 250/1something high/low respectively with the ambient air near 90F. I forgot the exact readings, it's been a while... but I remember it was in line with the R134 chart online for that air temp. AC comes out cool, but not like my wife's 2012 Civic, which blows snowballs. I measured the air and it's around 60F coming out of the registers, but sometimes, while I'm driving and don't have a thermostat handy, I feel that the air is closer to 75. That far left vent feels like it's ambient temp.

So what gives? I feel like I'm not low on Freon. Only thing I can think of is the expansion valve not opening properly. However, I've been getting pelted by the rotting vent insulation for years now. I'm wondering if maybe the vent door that mixes how and cold air has deteriorated and is allowing hot air to mix with my cold air. Has anyone had this issue and got to the bottom of it? I can hear my Expansion Valve actuating every now and then, and the air will get noticeably colder. I haven't figured out when/why it does that, as I can't seem to replicate it with varying engine RPM.
 

cidades

Veteran Member
Joined
Feb 17, 2010
Location
Portugal
TDI
Golf MK4 >> AHF(81kW)
With variable displacement compressor this car should maintain suction(low pressure) just a little under 30psi. High side appears to be OK at 250 for that 90F ambient.
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
Springfield VA
TDI
... None :S
And, are you sure the air blend door in the airbox is working? Recirc door closes?

Both radiator fans should be running on high with 250 PSI on the high side. If your car has a bunch of miles you might want to take the front of the car apart and clean between the rad and condenser. It can get quite dirty.



-J
 

Rembrant

Veteran Member
Joined
Oct 31, 2014
Location
Canada's Ocean Playground
TDI
2013 Golf TDI DSG
Sorry to jump in here, but since you guys are talking about A/C, are there specific places in the Mk4 A/C system that are common for leaks? If not, what is the best method for leak detection? Soapy water in a spray bottle I suppose?
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
Joined
Aug 16, 2004
Location
South of Boston
TDI
'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
If it's "been a while" since you measured the charge level and pressure, it may have changed. I tested IBW's A/C earlier this summer and charge was fine, but it doesn't blow as cold as it used to, about 44 at the vents instead of the 38-42 it used to be. My guru said it was probably a sticky expansion valve. However, as I've used it this summer its performance has improved. I'll probably replace the expansion valve next year.

I had a customer call me the other day with symptoms like you describe, and the shop he took it to said the compressor was failing. Maybe yours is, too. And the bad blend doors don't help because the cool air gets directed all over the car instead of to your face where it feels cool. Without the foam in the doors I don't think you're going to get a useful temp reading at the vents.

Rembrant, I think condensers are the most common leaking area on MKIV cars.
 

fruitcakesa

Top Post Dawg
Joined
Feb 18, 2007
Location
Vermont
TDI
04 jetta 5 spd wagon
Sorry to jump in here, but since you guys are talking about A/C, are there specific places in the Mk4 A/C system that are common for leaks? If not, what is the best method for leak detection? Soapy water in a spray bottle I suppose?
I have had mine checked both electronically and with uv activated coloring agent.
Its hard checking the Ex Valve with soap suds since it's tucked way back in there so the above methods work well.
 

Enabled

Veteran Member
Joined
Apr 23, 2013
Location
Houston, TX
TDI
2003 Jetta TDI Manual, BMW 328d SW
Mine was the expansion valve. Found out the expensive-er way after changing the refrigerant control valve without results.
 
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IDoSeaDoo

Veteran Member
Joined
Apr 13, 2011
Location
Raleigh, NC
TDI
2011 Jetta, CJAA 6spd
Well, I"ll probably sell this car before I fix it, but good to know. I think I actually overcharged the system a little as my Low side was higher than 30psi. And yes, the pipes were sweaty/cold on the low side. I just picked up a newer MK6 TDI with the lovely 6spd. Seems much lower quality than my MK4, but it's FAST and the seats are way better. No more seat bolster cutting into my femoral nerve :)
 

Fix_Until_Broke

Top Post Dawg
Joined
Aug 8, 2004
Location
Menomonee Falls, Wisconsin, USA
TDI
03 Jetta, 03 TT TDI
FWIW - the MkIV AC is rather sensitive to the mass of refrigerant in the system. When I had mine apart for engine swap, I recharged it with my gauges and tank until the line back to the compressor was cold/sweaty. Since it's an expansion valve system, the low side will be more/less constant at low 30's psi. It cooled, but not quickly. After 30 minutes it would cool down, but that used to be quicker.

I had a shop do an evacuate and refill using a fancy machine that measures how much came out and how much to put back in and I was surprised to find that the system only removed ~300g and it calls for 750g. Once refilled to 750g it was amazing how much better it worked - it would easily fog the windows on the outside when it was hot and humid, a good problem to have.

What I'm saying is that it's really hard to figure out if you have the proper amount of refrigerant in the system unless you start with an evacuated system and a scale and can put the right amount in.
 

chriserrol

New member
Joined
Aug 11, 2018
Location
Nova Scotia
TDI
2010 Jetta
So I have a 2010 Jetta TDI, and a/c is not working, took to to the dealer and the evacuated Freon and did a leak check, was a little low on Freon, so they replenished it and still no A/C. Both fans were running high and they said they confirmed the switches for Freon were working, they said it must be the compressor. So the next day I take it in and they replace the compressor and still no A/C. They said they have no idea what it is. Any advice would be greatly appreciated!
 

ToxicDoc

Veteran Member
Joined
Mar 1, 2018
Location
Virginia, US
TDI
2001 Jetta, S7, .216
So I have a 2010 Jetta TDI, and a/c is not working, took to to the dealer and the evacuated Freon and did a leak check, was a little low on Freon, so they replenished it and still no A/C. Both fans were running high and they said they confirmed the switches for Freon were working, they said it must be the compressor. So the next day I take it in and they replace the compressor and still no A/C. They said they have no idea what it is. Any advice would be greatly appreciated!
You should start a new thread to prevent the information being mixed up. A set of gauges would be helpful. You need to see if the compressor is getting power and if the clutch is activating. Also, maybe it's working but your blend doors are stuck closed.
 

needsmoarturbo

Well-known member
Joined
Mar 2, 2020
Location
utah
TDI
2011 JSW
Bringing this back from the dead what are the symptoms if the expansion valve vs rcv.
Already replaced the rcv and it acts same as before. Sometimes works after a while sometimes doesn't.
took it to an ac shop the recommended replacing the compressor and condenser to the tune of 1850 USD but when it does work it gets cold so I'm not sure I but their diagnosis
 

KLXD

Top Post Dawg
Joined
Aug 22, 2009
Location
Lompoc, CA
TDI
'98, '2 Jettas
This was on a 2002 not the 2011?

What work has been done to it in the past? You replaced the RCV in the compressor? Just making sure everyone's on the same page.

How was the system charged following this work?
 

werdna

Well-known member
Joined
Aug 14, 2009
Location
An obscure corner of northeastern Massachusetts
TDI
2003 Jetta Wagon, 2013 Touareg Sport
Since this thread seems to be the most popular one on expansion valves, here's another experience: my ('03 ALH Jetta) aircon has been iffy for years. Fans work, compressor has been replaced a couple of times over the years, and finally this year I had the expansion valve done. The old one was severely crudded up, and also probably contributing to premature compressor death.

Now the only problem I am having is that if I run straight AC to just the upper vents, it's so cold my face hurts. Seriously. The car has never ever been this cold. It's glorious!

One piece of advice: if yours has been sitting for as long as mine (19 years) you can save some time by picking up new bolts and the backing plate (1H0816831, dealer part, $50-60) as well, odds are pretty good the bolts and backing plate threads are not going to survive removal intact.
 
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