a/c compressor not engaging , Rad fans not going on

enatman

Well-known member
Joined
Apr 3, 2004
Location
PA
TDI
current 2006 brm, 2014 passat SE returned, 2000 jetta 404k (sold)
I checked everything on my 2000 jetta tdi automatic.

I noticed about three weeks ago I wasn't getting cold air when I turn on my a/c. the a/c light goes on, but no cold air. I did every possibly test on this forum. I replaced the FCM with a new one from ID parts. I checked the pressure with a refilling system and it says charged. The fans kick on high, but shut off immediately. BUT will not stay on when I turn on A/C

I checked the temperature switch under the plenum ..It works

I even purchased, but yet to install, the high pressure switch

Checked fans and replaced one, Both work when I put power to them

I checked ohms at high pressure switch and it seems correct.

What's left? I'm not getting the radiator fans to stay on when I turn on a/c and the compressor is not engaging?
 

enatman

Well-known member
Joined
Apr 3, 2004
Location
PA
TDI
current 2006 brm, 2014 passat SE returned, 2000 jetta 404k (sold)
Checked battery top fusebox and tested all fuses..No burned fuses
 

AndyBees

Top Post Dawg
Joined
May 27, 2003
Location
Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Turn the ignition to ON (do not start engine), turn cabin fan on low and then push in the AC button. If everything is working properly, the two fans out front should come on low speed. Also, make sure that the on dash (cabin fan) is actually running and the AC buttom is light up. If the on dash switch has gone kaput, the AC system will not operate. Turning it on signals the FCM to turn on the fans and engage the AC Compressor Clutch, assuming you push in the AC button.

Have you hot wired the AC compressor clutch to see if it "pops" when activated?

There is a 4-pin electrical connector just above the starter and below the battery. That connector contains the two wires that go to the AC compressor clutch and the other two wires go to the Alternator. See if that connector is damaged! Also, as I am sure you know, there is a 2-pin connector at the AC compressor...check it for damage too!

Lastly, you might want to consider re-installing the old FCM.

Hope this helps!
 

enatman

Well-known member
Joined
Apr 3, 2004
Location
PA
TDI
current 2006 brm, 2014 passat SE returned, 2000 jetta 404k (sold)
The high pressure switch NEVER goes bad..i spoke with three people and they told me the design is so simple..It doesn't have room for fault..I jumped it..i Only bough this in case something lead to that..So far It doesn't
 

enatman

Well-known member
Joined
Apr 3, 2004
Location
PA
TDI
current 2006 brm, 2014 passat SE returned, 2000 jetta 404k (sold)
Andy..I did that..from day one...the dash switch is not an issue. i'm going to hot wire the a/c compressor and look at wire above starter... BUT started and battery are on opposite sides? I'm thinking perhaps, my low speed may be burned on the fan, and not the high speed (as tested).. I have been looking at why fans are not coming on when a/c is turned on...perhaps the combination of no low speed and the clutch going bad?
 

enatman

Well-known member
Joined
Apr 3, 2004
Location
PA
TDI
current 2006 brm, 2014 passat SE returned, 2000 jetta 404k (sold)
A special thanks to Dan G.. My problem was... the pressure.. I was using a can of freon to check the system pressure.. It showed FULL... Not the case.. the can shows full at 25lbs.. When I filled to 27-30 the fans kicked on.. under 35lbs (depending on temp ect) is a good pressure.. Now I need to find the leak
 

DanG144

Top Post Dawg
Joined
Aug 2, 2007
Location
Chapin, South Carolina, USA
TDI
2005 A4 Jetta 5spd
He did not replace the sensor. His pressure was too low for ambient temperature, indicating a loss of charge. When he added some refrigerant, it raised the pressure, it cleared the interlock and the compressor and fans started working.
 
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