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#1 10-30-2008 15:18:18

deerhuntxj
Helper
Registered: 10-05-2008
Posts: 30

Re: AC problem on '98 XJ

On my '98 XJ the AC will run fine and blow very cold air for a while,
but on a long trip after the Jeep has been running for maybe an hour
the air is not as cold. Any ideas what may cause this?
thanks

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10-30-2008 15:18:18

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Re: AC problem on '98 XJ

#2 10-30-2008 15:18:46

scooter
Helper
Registered: 10-05-2008
Posts: 18

Re: AC problem on '98 XJ

just speculating

the vacuum motors that operate the blend doors in you vent system
aren't working right, so that you're getting some heat mixed in with
the cold. perhaps you have cracked or broken vac lines.

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#3 10-30-2008 15:19:11

deerhuntxj
Helper
Registered: 10-05-2008
Posts: 30

Re: AC problem on '98 XJ

thanks, I'll look into that.
It just seems odd that as I'm traveling it changes after about 40. min to an hour.
It's does not appear that it is mixing warm air in with the cold, but that it is not nearly as cold as it started out.  When I begin my drive the AC is ice cold and as I go on it tempers down to a mild cold at best.

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#4 10-30-2008 15:19:34

lekimxj
Helper
Registered: 10-05-2008
Posts: 16

Re: AC problem on '98 XJ

Another area to examine is the A/C system is over charged.  This can cause any A/C system to get to cold.  Stop at a shop/garage that has the gauges to check A/C.

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10-30-2008 15:19:34

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Re: AC problem on '98 XJ

#5 10-30-2008 15:20:15

rapsen
Helper
Registered: 09-27-2008
Posts: 20

Re: AC problem on '98 XJ

Nope.  An overcharge will cause your low side saturation temperature to be too high and it cools less.

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#6 10-30-2008 22:52:56

bagman
Helper
Registered: 10-05-2008
Posts: 23

Re: AC problem on '98 XJ

After thinking about this a little, I would suggest that the system is probably under charged.  This causes the evaporative coil temperature to be too cold, below freezing.  Normal coil temp is around 35 degrees.  When the coil temperature dips below 32 degrees the moisture that condenses on it will freeze instead of running out the condensate drain through the firewall.  Eventually the coil freezes enough that it becomes plugged with ice, hence you will not get cool air from it.  You can check this yourself by looking at the sight glass on the filter-dryer.  It is located on the passenger side frame rail.  It is a little green piece of glass in the top where the AC hose goes to the TXV on the firewall.  With the AC running, you should see clear liquid or very tiny bubbles passing periodically.  If you see large bubbles,  it is undercharged.

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#7 11-04-2008 16:10:42

nunner
Newbie
Registered: 10-05-2008
Posts: 5

Re: AC problem on '98 XJ

I would go along with this.  I see a LOT of air conditioners that do this, either because of an undercharge or dirty filter/low air flow/low t-stat setting causing them to freeze up.

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