[xj40] AC Blower

I have a 1990 XJ40. When the AC is turned on the blower motors
appear to be functioning but no air is coming out of the dash
vents. The little air that is escaping appears to be cold so I do
not think the freon is low . Are the directional doors vacuumed
operated or where would I start to check.Thanks–
WIDGET33
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In reply to a message from VETTEMAN sent Wed 1 Mar 2006:

Have you checked (by pulling / replacing the blower fuses
alternately) that both blowers are operating? If one is out,
the majority of the output from the other will merely flow
past the dead blower and not out of the vents.

The XJ40 archives contain comprehensive information on the
proper operation of the HVAC system which is well worth
reading. Most recently George B summarised the blend and
vacuum operation in this post (from the archives) :-

http://forums.jag-lovers.org/avsn.php?822543k26--
The original message included these comments:

I have a 1990 XJ40. When the AC is turned on the blower motors
appear to be functioning but no air is coming out of the dash
vents. The little air that is escaping appears to be cold so I do
not think the freon is low . Are the directional doors vacuumed
operated or where would I start to check.Thanks


Bryan N, '91 Sovereign 4.0 L, (RHD)
Cambridge, United Kingdom
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In reply to a message from VETTEMAN sent Wed 1 Mar 2006:

Brain’s probably right; he usually is!

The way this seems to work is that air comes out of the middle vent
from the two blowers working against each other. If one isn’t
working, like he said, you get a sad trickle of cold air in the
floorboard of the one that isn’t working. Interesting design that
works fine if both blowers are working.

Dan–
'91 Vanden Plas
Houston TX, United States
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the blower has quit working on my 94’, is there a seperate ground
wire for them. the problem started when the radio and the blower
wounld not work for a min or 2, then they would both come on…now,
the radio is working and the blower isn’t…also at 1st the ac
wouldn’t come on either, but it and defrost lights come on
now…tks for the help Jeff–
jsm
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What vent are the AC supposed to blow out of? Mine are only blowing
through the defrost vents on the upper dash on the windshield. It’s
a 1989 XJ6–
JEFFREY OTERO
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In reply to a message from JEFF4292 sent Thu 10 Jul 2008:

The A/C should blow through all BUT the windscreen vents.
Most of the air should exit via the center vent in the dash,
with lesser amounts exiting the side dash vents and even
less out the foot well vents.

Common problems include broken windscreen vent flaps which
break in the ‘‘open’’ position and failed center vent flap
which fail in the ‘‘closed’’ position.

One common point of failure is the vacuum source itself.
Vacuum is used to hold the windscreen vents closed and to
open the center vent. Vacuum solenoids are below/behind the
radio on the right side. Can be accessed by removing the
right side knee pad and frame.

Vacuum canister is under the battery.

I’d start by checking vacuum to the canister, then I’d test
the center and windscreen vents by bypassing the solenoids
to further isolate the problem(s)–
The original message included these comments:

What vent are the AC supposed to blow out of? Mine are only blowing
through the defrost vents on the upper dash on the windshield. It’s
a 1989 XJ6


91 XJ6, 93 Sov, 97 Sov – Driveway’s crowded!
Tampa Fl, United States
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I think this has been covered but I can’t find an answer to
my specific questions so here goes…

My '88 XJ40 is cooling but the passenger (RH) side blower is
not working. I have the air coming through the cowling
outside in front of the windshield and woefully inadequate
cooling and air movement. I think these are two separate issues

I checked the right hand fuse and it was not only blown but
melted and crumbled when I tried to remove it. That
convinced me I needed to remove the blower so I’ve gone
through all that pain and have the blower on a bench in the
shop.

The fan does not turn easily. Rather, it turns but will not
‘‘coast’’ more than a few revolutions after spinning it with a
finger. I straight wired it to a battery and it runs fine. I
lubricated the bearings and looked at the brushes- more than
3/8’’ on them. I noticed the temporary wires getting warm so
I decided to run it through A 10 AMP fuse to see if the
motor had excessive resistance (it runs off a 20 AMP fuse in
the car) and although the 10 AMP fuse got warm it ran for
almost 5 minutes with no problems.

I guess my questions are:

  1. Should the fan ‘‘freewheel’’ a little better?
  2. I think the air going outside problem is in the vacuum
    system. Are the vacuum actuators known to go bad?
  3. How can I test the relays and Darlington transistor etc.
    while I have the unit out of the car? I do not want to go
    through this again.

Thanks–
Mogrits
South Carolina, United States
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In reply to a message from Mogrits sent Sun 21 Aug 2011:

If you have the blowers out, why not make a couple of flappers to
close off a bad blower if it stops. I posted a couple of photos in
my album. They fit loose and pivot on a piece of coat hanger wire
I soldered an inch in from one end. I simply drilled holes in the
plastic for the wire to project from as pivots. Now when the
blower blows, the flap opens and lays flat against the heat sink
for the Darlington transistors and when the blower stops, gravity
closes the flap and prevents air from leaving through a dead blower.
The blowers should coast for a while. The bearings should offer a
faint resistance, but it would be hard to even feel the
resistance. Lubricate the bearings with Liquid Wrench or other
penetrating oil and run it on the bench for some time to loosen
things up.–
The original message included these comments:

The fan does not turn easily. Rather, it turns but will not
‘‘coast’’ more than a few revolutions after spinning it with a
finger. I straight wired it to a battery and it runs fine. I
lubricated the bearings and looked at the brushes- more than
3/8’’ on them. I noticed the temporary wires getting warm so
I decided to run it through A 10 AMP fuse to see if the
motor had excessive resistance (it runs off a 20 AMP fuse in
the car) and although the 10 AMP fuse got warm it ran for
almost 5 minutes with no problems.
I guess my questions are:

  1. Should the fan ‘‘freewheel’’ a little better?


Pete Peterson 70E(193K) 88XJ40s(253K & 242K) 94XJ40 (122K)
Severna Park, Maryland, United States
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In reply to a message from Mogrits sent Sun 21 Aug 2011:

I fixed my fans last month and they both worked when hooked
up directly to the fan motor, but not in the car. The
relays were both new. The replacement fans work fine with
out changing anything else, which meant it had to be the
electronic speed controller on the fan box.

You can rebuild those if you want for a lot less than a
whole new or rebuilt fan assembly. It seems age and
moisture eventually do them in.

http://www.kelsey-forums.co.uk/cgi-bin/jwm/YaBB.pl?num=1218411150/0

Both fans have to be working to have air come out the vents.
What you noticed is the air from the drivers fan is taking
the path of least resistance and going out the fresh air
intake for the passenger fan.–
'88 XJ6 - Austin, TX
Austin, TX, United States
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