A/C not cooling at idle

Steelhead19

Member
Joined
Nov 5, 2015
Location
Virginia
TDI
2005 passat
so I noticed the other day my a/c unit is not cooling at idle, however when I get going it starts to cool down. As soon as I stop it stops cooling again. any suggestions?
 

Scubanero

Veteran Member
Joined
May 30, 2007
Location
Calgary AB
TDI
2005 Passat Wagon
The electric fan (passenger side, behind the radiator) should run whenever the AC is on and the key is ON (doesn't need to be running). Yours is likely not. The problem might be a dead fan, or a relay problem. Test the fan by putting 12VDC on the connecter, which is located under the power steering reservoir. If the fan is OK, look into the relays. Search this forum for more details.
 
Last edited:

fastcar4re

Veteran Member
Joined
Sep 3, 2008
Location
Houston, Texas
TDI
2015 Jetta TDI SEL (purchased as "new" in May 2017).
I am almost certain that there is also a mechanical fan with a clutch, in addition to the electric fan. The clutch could be bad on the mechanical fan.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Check the electric one first, pretty common. You could also have a weak compressor or a gunked up orifice tube. The B5s did not get the expansion valve system, unfortunately.
 

Steelhead19

Member
Joined
Nov 5, 2015
Location
Virginia
TDI
2005 passat
I had a check engine light recently with a code for coolant temp sensor, would that cause that fan not to run?
 

auntulna

Veteran Member
Joined
Mar 13, 2005
Location
Springfield, MO
TDI
05 GLS Passat wagon, mit panzer plate
If your electric fan is original, 12 years old, it's not too reliable anymore. "So", some days it runs and others it doesn't. If it's not running, and it can run because you gave it a boost with your fingers, it is shot. And look up the 384 relay; take it out and inspect. You might find the faulty solder connection that happens to it. Both could be bad at the same time!
 

Steelhead19

Member
Joined
Nov 5, 2015
Location
Virginia
TDI
2005 passat
So its my understanding that the fan should run all time when the a/c button is on? and the thermostatic sensor turns the fan on when engine coolant temp hits a certain temp? The fan is on sometimes when I look at and other time its not. When I hook 12vdc into the connector the fan turns on. Before I continue troubleshooting I just wanna make sure I understand completely how it should be operating. cant troubleshoot something if you don't know what it should be doing. sorry for my dumb questions but new to these vw's.

Thanks
 

auntulna

Veteran Member
Joined
Mar 13, 2005
Location
Springfield, MO
TDI
05 GLS Passat wagon, mit panzer plate
Yes, if the key is on, fan switch is on, AC button is in, fan should be running. Some folks have mentioned a nonmoving fan with those conditions will start running when you push the blades with your fingers; if so, that is a bad fan.

Plus, the 384 relay can become intermittent because of a faulty solder joint. Take off the side panel on the dash you see when you open the door. You can then see the # 384, and pull it off with fingers. Take the cover off and look at the solder joints closely. There is one that is susceptible to a crack. It can be fixed, and it can be good to have a spare, if you like. Good luck!
 

Steelhead19

Member
Joined
Nov 5, 2015
Location
Virginia
TDI
2005 passat
so I was finally able to check the fuses and relays, all are good. hooked up 12vdc to fan and got no movement. seems as though I need to replace the fan. Looks like a real pain in the butt to get that thing out of there.
 

Steelhead19

Member
Joined
Nov 5, 2015
Location
Virginia
TDI
2005 passat
So I replaced the fan and it is now working well, and cooling at idle. Thanks for all the help.

Also as stated above its not that big of a job to change, just one screw. Only pain in the rear is re-routing the wire. all in all about an hour job or so.

Thanks again
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Yeah, the wire is a bit fiddly to get routed back correctly, but not too awful. Just takes patience.

Glad you got it working good!
 

Garageman1965

Active member
Joined
Jul 18, 2017
Location
Moline Illinois
TDI
2005 wagon silver
I have the same problem works while moving but warms up at idle, replaced the electric fan, 384 relay, the clutch on the mechanical fan, drained and replaced the orifice tube and recharged still the same problem any suggestions would be appreciated
 
Top