You can't. What's going on is a loss of vacuum to your HVAC controls. It's likely that you have a vacuum check valve, vacuum line or vacuum reservoir that is leaking or that has failed. Just left of center, under the hood and attached to the Firewall is a vacuum canister and a "T". Usually, the problem is the check valve (the "T") but could be a broken vacuum line.
all air flow is coming out from the defrost vents in front windsheild . how do i manually change it to the vent position
2004 Mercury Grand Marquis LS Premium
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Maintenance & Repair
My '05 Grand Marquis has 140K miles. Recently the front a/c vents quit blowing cold air. For the next 2 weeks we drove it with cold air coming out of the vents on top of the dash only. After 2 week...
2005 Mercury Grand Marquis GS
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Maintenance & Repair
I just don't know if the seat can be raised or how to do it
1997 Mercury Grand Marquis 4 Dr LS Sedan
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Maintenance & Repair
How do I remove the old heater hose in a 2000 mercury grand marquis?
2000 Mercury Grand Marquis LS
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Maintenance & Repair
what is the physical process to replace the fan blower switch that is located in thge dash board ?
2008 Mercury Grand Marquis LS
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Maintenance & Repair
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