Question about Cars & Trucks

Open Question

1998 Freightliner FLD only blows through defroster vent

Posted by Anonymous on


5 Suggested Answers

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
New users get 2 Free calls (no credit card required) and instant help on almost anything you can think of (from cars to computers, appliances, handyman, and even pets).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017

  • 20 Answers

SOURCE: Heat wont blow through heater or defroster vents

common problem, check under dash by the gas pedal if control arms are muving went selecting from ac to heat cuz this it is the control for the vents to go from ac to heat and to defrost.

Posted on Feb 23, 2009

  • 37 Answers


Sounds like you have a supply vacuum problem. When you lose supply vacuum to the control head it defaults to defrost.

Posted on Mar 13, 2009

  • 1889 Answers

SOURCE: 1999 f350 ac blows from defrost vents instead of ac vents

check for a vacuum line that has fallen off the diaphram vacuum "switch can" near the vent shift lever at the heater box under the dash passenger side

Posted on May 28, 2009

  • 8518 Answers

SOURCE: all air blows out defrost vents only. 1998 ford

Fixed one of these recently--it was a "T" in the vacuum line from the engine near the control switch. The "T" branches to a separate switch on the panel. I cut out the old "T" and spliced in a new one.
Your leak may be elsewhere. Typically, it's where the vacuum line connects to the engine intake manifold, where a hase is used to make the connection there. The other typical failure is the control switch itself. You can access the back of the control panel by taking out 4 screws and pulling it forward. Pull the vacuum connector off the switch and start the engine. The black line coming into the connector should have the engine vacuum on it. If no vacuum, check that "T" and the connection to the engine. If you have vacuum to the switch, the switch is probably bad. You can verify by putting the connector back on and listening for a leak in the switch. If I'm not making sense or you're not familiar with vacuum controlled HVAC, please reply with any questions.

Posted on Sep 15, 2010

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

2 Answers

1998 Dodge Stratus - Air conditioning is blowing through the defrost vents

Vacuum controls this circuit and leaks will cause blend air door to default to defrost. Check for bad check valve or hose leaks under hood first as these are the easy ones to get at and under hood heat causes deterioration.

Jul 08, 2015 | 1998 Dodge Stratus

1 Answer

1998 dodge durango air not blowing through vents

most likely your controls are bad or a vacuum leak in dash

Mar 21, 2012 | 1998 Dodge Durango

1 Answer

A/c and heater only blows thru defrost and side vents

your a/c and heater blow thru the defrost ( top of dash? ) and the vents. Or defrost/or the vents.? and not on the floor? Well all of these should work. can you hear the motor inside the dash turning to they're perspective spots on the dial the motor pulls a cable and closes or opens appropriate doors as the selector switch is moved. if not the switch may be faulty. and you can get it from a parts store or dealership. CK the parts store's first they will be cheaper and will be able to give you a look at what needs to be done to replace it. But it can be done on most "fine " cars in 20- 30 min with minimal hand tools.

Mar 26, 2009 | 1998 Mercedes-Benz C-Class

1 Answer

1998 Mercedes C280 Sport only a/c blows thru defrost/ side vents

hi, seem you have vacuum problem,open your hood look for your vacuum distributor maybe have disconnected vacuum hose,ty

Mar 26, 2009 | 1998 Mercedes-Benz C-Class

1 Answer

1998 Mustang - AC blows only through Defrost vents

You probably have a vacuum leak on the passenger side. its a small plastic hose some times they come unpluged from the engine. or brake.

Jan 05, 2009 | 1998 Ford Mustang

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

150 people viewed this question

Ask a Question

Usually answered in minutes!

Top Cars & Trucks Experts


Level 3 Expert

76630 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22219 Answers

Randy Ohler

Level 3 Expert

14585 Answers

Are you a Car and Truck Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides