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It's a vacuum leak somewhere in the system. There are several vacuum lines that operate the blend doors on the system. If there is a leak where the system will not hold vacuum, it will default to defrost automatically.
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∙ 14y ago
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Why won't your 2003 Jeep Wrangler Sport's AC blower not change from defrost no matter what you have it on?
Check for a vacuum leak either under hood or under dash Check the operation of the vacuum actuators under dash Check the operation of the selector switch Defrost is the default settting for this system
What is the switch under the air conditioning controls on your 2003 Jeep Wrangler for?
rear wiper, rear defrost
Why is my 2003 trailblazer stalling while idle and heater is on?
If defrost is on it could be your compressor going bad. See what happens when you leave off defrost or disconnect your compressor. It only controls defrost and air conditioning. I had the same problem
Where is the Heater fuse on a 2003 jeep wrangler?
open the glove compartment fuse box is right behind
You have and antifreeze smell in your 2003 Nissan when the heat or defrost is turned on what should you do?
you probably have a leaking heater core....you can replace it or bypass it
2003 jeep wrangler heater fan switch works on high only?
Replace the blower motor resistor.
Do you need an engine block heater for a 2003 Jeep Wrangler?
Not unless you are in an area with temps way below 0F all the time.
How many valves does the 2003 Jeep Wrangler have?
The 2003 Jeep Wrangler has 16 valves.
Is the 2003 Jeep Wrangler electric or gas?
The 2003 Jeep Wrangler is a gas-powered vehicle.
What size engine does the 2003 Jeep Wrangler have?
The 2003 Jeep Wrangler has an inline 4 engine.
What kind of transmission does the 2003 Jeep Wrangler have?
The 2003 Jeep Wrangler has a 5-speed manual.
What is the cause of a heater fan in a 2003 Alero to only make noise when on the defrost setting?
was there something on your dash that fell in the vent, a bad fan will make noise all the time.
