HVAC gone crazy

[Donald]

90000+ miles on car. This week, all of a sudden, I can get no air out of the dash vents. Auto, Max A/C, A/C, Vent, Floor, Flr Def, Def. Nothing gives air from dash vents. On Max A/C and A/C I get cold air on my feet and the windshield vents. Heat, same thing.

Help!

[fastblackmerc]

You have a vacume leak somewhere. Modern cars have a failsafe HVAC system. If you lose vacume you'll get defrost so you can see out the front window. Check all the vacume lines inside and out. If you've had any recent work done in the engine compartment or dash area, check that area fist.

[Donald]

Thanks. Will check it out. Hood has not been opened for a month or more. Same with under dash work. Nothing for 2 years, at least.

[johnjamis]

I had this problem on my 1996 grand marquis. After spending nearly $1000 at the dealer, I went to the local junk yard and bought a used electronic control head for $75. This was easy to replace and fixed the problem. Good luck.

[Donald]

Well, I have the manual set and one of those eBay DVDs. If I can't find it the dealer gets it. I have 9000 miles left on my extended warranty!

[SergntMac]

Look up HVAC "blend door", a few of us here have replaced that already

[Blackened300a]

I had this problem and the dealer replaced the Dashboard control unit and I havent had any issues since

[magindat]

At 90K, I'd look for a dried, craked line or a line that may have fallen off. Will likely be in the area to the passenger side of the motor towards the firewall.

[Donald]

Another sympton. Driving home with Max A/C and temp set for 60. Just tooling along and all of a sudden I get blasted by cold dah vent air. But then I noticed it went away about 10-15 seconds after I went WOT. Then it came back. This was repeatable a few times but then it stuck with no dash vent air.

I found the vacuum hose area but it is too hard to get to given that I still have a warranty. Let Mercury do it.

[Donald]

Well, at this point I think the dealer is trying to stick it to me. They are telling me that initial checking indicates the after market radio installer pinched a hose. I told the service rep that I have not driven the car for 90000 miles with no air from the dash. They are continuing to look.

[fastblackmerc]

They is a vacume leak somwhere, could be the HVAC head unit or somwhere in that area if you've had an aftermarket radio installed. Pinched, cut, or disconnected vacume hose.

[Donald]

Well, they saw the light. Decided it was the EATC. Glad I have an extended warranty. Retail for the part is $482. Part is on order.

They told me the peeling leather wrap on the steering wheel would require a new steering wheel. I passed. I think a little gorilla glue will fix it.

Light on the up-down switch for the driver window fixed.

Can't find any reference to the fact the whole switch panel was loose.