ACTION NAPA AUTO Parts - (Page 35)
Case study: 1999 VW Jetta - A/C fuse
T
echnicians working on a third generation Volkswagen Jetta might find their A/C controls totally inoperable, including no blower fan operation amongst
any of the fan speeds, and no operation of the A/C
button or recirculation button. Even the backlights
behind these buttons may not illuminate. A possible cause could
be similar to what was found on this 1999 Jetta.
Fuse # 25 is listed as the "Fresh Air Blower, Clima-
chanical refrigeration circuits. I went right after the fuse
panel in the driver's door jamb to inspect the fuses.
Before going all out and testing every fuse in the panel,
I decided to look up the fuse function arrangement in my
service information system. When I found the right chart,
I printed out those pages, and using a yellow highlighter,
marked all the fuses related to the A/C system. That way,
when I took the pages out to the shop to start my testing,
I knew exactly which ones to look for. I even highlighted
their colors and positions in the panel to make identification easier. The nice thing about taking this extra step is
that you can save time by not testing unrelated fuses, and
go right to the potential problem areas.
Operator's control panel for this '99 Jetta has
ON/OFF buttons for both A/C and Recirculation.
tronic, A/C" fuse, but actually powers most of the A/C
control panel as well. When this car came into the shop,
the "AC" button on the controls would not light up when
depressed. Since the vehicle was recently in for service,
and the system was known to be in good working condition, I figured it had to be something other than the me-
The cabin fuse panel on the Jetta can be found
by opening the driver's door and removing the
access cover.
Turns out that fuse # 25 was the culprit, and a new fuse
took care of this problem. The vehicle owner was happy
to again have a working blower motor, not so much for
use with the A/C system, but primarily because of the potential safety issue surrounding an inoperable windshield
defogger.
Taking things one step further
The cabin fuse panel on the Jetta can be found
by opening the driver's door and removing the
access cover.
Adding a bit to this diagnosis called for checking the
blower motor current draw. After all, that would be the
correct way to test the system after fuse replacement and
verify it's operating properly. Keep in mind that fuse
number 25 was replaced (which is a 25 amp fuse), and I'm
not exactly sure why it blew in the first place; the system
wasn't working and replacing the fuse fixed it. I normally wouldn't bother to find out why or verify the repair
Spring 2015 * ACTION/NAPA
35
ACTION NAPA AUTO Parts
Table of Contents for the Digital Edition of ACTION NAPA AUTO Parts
Engine Cooling Systems: Electric cooling fan operating strategies
The next 609 is here
Computer controls for air conditioning compressors
Getting legal
Mechanical fan clutch diagnosis
Properly mixing coolant
Selling the right things
Ford 6.4L Powerstroke
A big bad leak, but where
Recovering the entire charge
Blower Motor Mystery
Case Study: 1999 Jetta A/C Fuse
System Charge Determination
ACTION NAPA AUTO Parts - Cover1
ACTION NAPA AUTO Parts - Cover2
ACTION NAPA AUTO Parts - 3
ACTION NAPA AUTO Parts - Engine Cooling Systems: Electric cooling fan operating strategies
ACTION NAPA AUTO Parts - 5
ACTION NAPA AUTO Parts - 6
ACTION NAPA AUTO Parts - 7
ACTION NAPA AUTO Parts - The next 609 is here
ACTION NAPA AUTO Parts - 9
ACTION NAPA AUTO Parts - 10
ACTION NAPA AUTO Parts - 11
ACTION NAPA AUTO Parts - Computer controls for air conditioning compressors
ACTION NAPA AUTO Parts - 13
ACTION NAPA AUTO Parts - 14
ACTION NAPA AUTO Parts - 15
ACTION NAPA AUTO Parts - Getting legal
ACTION NAPA AUTO Parts - 17
ACTION NAPA AUTO Parts - Mechanical fan clutch diagnosis
ACTION NAPA AUTO Parts - Properly mixing coolant
ACTION NAPA AUTO Parts - 20
ACTION NAPA AUTO Parts - 21
ACTION NAPA AUTO Parts - Selling the right things
ACTION NAPA AUTO Parts - 23
ACTION NAPA AUTO Parts - 24
ACTION NAPA AUTO Parts - 25
ACTION NAPA AUTO Parts - Ford 6.4L Powerstroke
ACTION NAPA AUTO Parts - 27
ACTION NAPA AUTO Parts - A big bad leak, but where
ACTION NAPA AUTO Parts - 29
ACTION NAPA AUTO Parts - 30
ACTION NAPA AUTO Parts - Recovering the entire charge
ACTION NAPA AUTO Parts - Blower Motor Mystery
ACTION NAPA AUTO Parts - 33
ACTION NAPA AUTO Parts - 34
ACTION NAPA AUTO Parts - Case Study: 1999 Jetta A/C Fuse
ACTION NAPA AUTO Parts - 36
ACTION NAPA AUTO Parts - System Charge Determination
ACTION NAPA AUTO Parts - 38
ACTION NAPA AUTO Parts - Cover3
ACTION NAPA AUTO Parts - Cover4
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