dash air/heat only coming out defrost

[jim d.]

I have 2003 32ft. knight the air flow only comes out the defroster, thanks for any help you can give, thanks jim d.

[CJ7365]

Originally Posted by jim d.

I have 2003 32ft. knight the air flow only comes out the defroster, thanks for any help you can give, thanks jim d.

I am not familiar with your coach, but usually when the climate control goes to defrost it is a vacuum leak, there is a vacuum ball located in your engine compartment, once you find this you can trace back the vacuum lines, they will go into the cab and under the dash board to your climate control switches, they get old and dry rot

[jacwjames]

X2 you have a vacuum problem as the system defaults to defrost if there is no vacuum

On the front firewall there is probably a small vacuum pump (generator) besides the black ball. My vacuum pump is actually mounted in a small black box. Here is a link to one the "might" be like yours.


http://www.evanstempcon.com/servicep...ullID=RV218234


If there is a vacuum leak you should hear a clicking noise as it will be running. In this case just trace all the lines to make sure they are connected, this includes the dash controls. If the vacuum pump is not clicking that indicates another problem, possibly electrical.

Let us know what you find

[Captjake1]

Mine did the same while back. Found the pump and rapped on it lightly with a small hammer (with the ignition on so power is to it) and it began to run. I think mine quit from lack of use and now runs fine.

[Tony Lee]

The vacuum pump generally runs for a few seconds when you turn the ignition on but usually drowned out by air buzzers and chimes. Also runs if you make major changes to the dash controls. Motor is controlled by an integral vacuum switch.

If you can check that there is power to the unit when ignition is on, but it still isn't running, then replacing the whole unit isn't expensive and is an easy job.

If there is a leaking vacuum line then the motor will run all the time so that is one way you can figure the difference. In that case disconnect the line going away from the unit and block the 'outlet' with your finger. If the pump stops running, the leak is external.

Unit on mine was unplugged when I bought it and ran continuously when plugged in, but that was due to a faulty vacuum switch and I was able to pull it apart and adjust it and it is still OK 5 years later. Middle name is Scrooge.

[stan5711]

Jim I have a 2002 knight and had the same problem,on the back of your of your firewall you will see a black metal box with a hose and two wires coming out of it,you will have to remove that box and the pump is on the inside of the box,your pump will look a little different than the one that was pictured here but that's the one you will have to go back with and just leave off the box,you can find the pumps on ebay,when you unplug it, hook it up to 12volts and see if it works.

[jim d.]

Thanks guys, I will cheek out the pump, it doesn't run will try taping it to see if that works and if not I will take it apart. will let everybody know how it works out Jim D.

[Duoglide1]

X 2. I'm in the same predicament. Thanks for posting this!


2007 Monaco Executive 45' 525 ISX

[jim d.]

Got to work on my Knight yesterday, vacuum pump was bad, it would get warm when the key was on and heat switch was on. Found a 2009 f250 {diesel} ford at the junk yard and removed the vacuum pump and plug wire harness for $35.00 installed on the motorhome. Turned key on and pump ran great but didn't shut off, so now I must have a vacuum leak which was the reason the pump was bad. Found the leak under the dash, it was a small red hose going to control switch. 2000 -2012 f250 &f350 diesel has the vacuum pump you need if you can find it. jim

[mel s]

Originally Posted by jim d.

Got to work on my Knight yesterday, vacuum pump was bad, it would get warm when the key was on and heat switch was on. Found a 2009 f250 {diesel} ford at the junk yard and removed the vacuum pump and plug wire harness for $35.00 installed on the motorhome. Turned key on and pump ran great but didn't shut off, so now I must have a vacuum leak which was the reason the pump was bad. Found the leak under the dash, it was a small red hose going to control switch. 2000 -2012 f250 &f350 diesel has the vacuum pump you need if you can find it. jim

Here's a new one: http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

[jim d.]

Originally Posted by mel s

Here's a new one: http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1

The problem with that pump is I don't have a pig tail that fits.

[mel s]

Originally Posted by jim d.

The problem with that pump is I don't have a pig tail that fits.

Here's the same pump with a new pig tail included.
Amazon.com: APDTY 015325-Kit Electric Vacuum Pump With New Wiring Harness Pigtail Connector (Multiple Custom Uses) (Can Be Used To Add Vacuum For HVAC, Cruise Control, 4WD Systems) (Factory On 2003-2004 Dodge Cummins 5.9L Diesel & 1999-2007 Ford 6.0L
Mel
'96 Safari

[jim d.]

Originally Posted by mel s

Here's the same pump with a new pig tail included.
Amazon.com: APDTY 015325-Kit Electric Vacuum Pump With New Wiring Harness Pigtail Connector (Multiple Custom Uses) (Can Be Used To Add Vacuum For HVAC, Cruise Control, 4WD Systems) (Factory On 2003-2004 Dodge Cummins 5.9L Diesel & 1999-2007 Ford 6.0L
Mel
'96 Safari

Thanks Mel. Jim d.