1987 Reliant air from vents goes away when accelerator press

1987 PLYMOUTH RELIANT
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CLETUS77
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1987 Plymouth Reliant, 50000 miles, V4

The air blowing out from vents. On Panel, air blows out strong until pressing accelerator pedal where air goes away and suddenly starts blowing out floor vents. On Bi-Level, air blows out both dash and floor until accelerating, then all air comes out floor vents only. On Floor, works fine. Air blows out dash vents on Panel setting only when not accelerating or car idle. Do I have a vaccuum or suction problem with a hose that's rotted? Is this something I can look for and fix? It does this whether on AC or fan only. AC does cool but will only exit floor vents when accelerating, no matter what position vents are set on. Any thoughts I would appreciate.
Extra information: Back in 1988, this car had dye put in AC system to find a leak. Freon has leaked out in past, but has not needed recharging in 2 years and does cool.
Jul 9, 2007 at 10:33 AM
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JACOBANDNICKOLAS
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Hi:
Yes it sounds like a vacuum leak. The vents in the HVAC are actuated by vaccum. When you put a load on the engine, the vacuum drops allowing less to the vents. Thus, the direction of the air changes. Check for vacuum leaks under the dash, at the switch, from the engine through the firewall to the switch...

Listen for a hissing sound that may indicate a leak.

Let me know what you find.
joe
Mar 22, 2009 at 12:49 AM