a/c vents

Winkle · 11-04-2009, 07:56 AM

My 97 e-350 clubwagon blows air in defroster only. How do i check vent door?

Cuda_Jim · 11-04-2009, 08:21 AM

You probably have a vacuum leak. The HVAC will default to defrost when it looses vacuum for safety reasons.....you need to see where you're going.

What engine do you have, the vacuum distribution is different for each.

Winkle · 11-04-2009, 09:48 AM

Quote:

Originally Posted by Cuda_Jim

You probably have a vacuum leak. The HVAC will default to defrost when it looses vacuum for safety reasons.....you need to see where you're going.

What engine do you have, the vacuum distribution is different for each.

I have a 5.4liter V-8.

Cuda_Jim · 11-04-2009, 10:13 AM

I forgot to say, If you've had the engine cover off recently the vacuum hose may have been knocked off...it's a good place to start. Also, look down by the passenger side feet area.
Here's a couple diagrams.
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Winkle · 11-06-2009, 10:04 AM

Thanks for suggestions and diagrams. I have checked vac lines to control motor in dash. The blue line has no vac. to motor/diaphram that opens dash vents. Must I remove dash to trace leak?

Cuda_Jim · 11-06-2009, 03:15 PM

Quote:

Originally Posted by Winkle

Thanks for suggestions and diagrams. I have checked vac lines to control motor in dash. The blue line has no vac. to motor/diaphram that opens dash vents. Must I remove dash to trace leak?

If you have vacuum on the supply (black line) then the switch is bad or another line is leaking (red, yellow, blue or white)
If there is no vacuum on the black line you need to check under the hood. Trace it back from the switch(s).

Winkle · 11-08-2009, 07:07 AM

Can you tell me where vacuum tank is located?

Cuda_Jim · 11-09-2009, 07:02 AM

The vacuum reservoir is located on top of the right frame rail behind the headlight assembly. The vacuum check valve is built into the reservoir. The reservior may be cracked, test it by pulling a vacuum on it, it should hold for more than 2-3 minutes. You can rent a hand operated vacuum pump from AZ for free.

The vacuum is routed inside to the function control switch, the vacuum motors, and the heater core water control valve through a color-coded vacuum hose harness I mentioned above.

BroncoJoe19 · 11-09-2009, 09:26 AM

You might be able to connect a hose and draw down a vacuum by mouth. It's not particularly pleasant, and probably not healthy, but a one time deal, proably won't kill you.

Cuda_Jim · 11-09-2009, 09:31 AM

Joe, that job sucks hehe!