Ford Crown Vic 5.0 A/C blowerquestion....

[Hawklover]

So I know this is a brand "X"........but I know someone will have an answer I can understand.
The a/c and heater blower motor starts and stops depending on the relative position of the gas pedal..........so I know I have to find the vacuum leak, either the "coffee-can" is shot, the vac valve attached to the vac tree under the hood, or one or more of the hoses have cracks...........what I have trouble understanding is how can the blower motor which is electrical, stop, start, and run slow, depending upon the engine vacuum? In other words how can vacuum control an electric motor?

Thanks in advance for the education.

[studegary]

Is the motor stopping (electrically) or does it just seem that way due to the opening/closing of air movment doors with a change in vacuum?

[Hawklover]

Motor stops or slows down....depending on gas pedal position.

Is the motor stopping (electrically) or does it just seem that way due to the opening/closing of air movment doors with a change in vacuum?

[Hallabutt]

Before you jump to any radical conclusions, check your battery connections, and any cable ends that may have been added. I suspect that it's not getting enough current flow. The car will most often start fine but the blower motor will operate erratically or not at all. I have experienced the problem several times with my Mark VIII. Sometimes it happens when it's been wet out and I have ignored the connections for several months. In that case just driving it dries out the connection issue enough that the return trip it works fine. It's a good reason to clean your terminal anyway, if they are like mine they usually need cleaning.

[wittsend]

Not sure what year your Crown Vic is or the RPM's when you are getting the cut-out. But, I had an '88 Turbo Coupe (T-Bird) and the ECU was designed so the compressor would cut out above 4,500 RPM. Can it be (since the gas pedal might be in the area of the wires) that the linkage of the pedal is hitting the wiring and tugging the connector loose enough to stop the fan but restoring it when the pedal is backed off.

I video Sunday services at my church. One camera would "flash" periodically. For years I traced down the camera circuits, replaced the power supply, checked the power outlet etc. Then one day I saw a guy rocking his chair back and forth. It was just enough of the chair leg hitting the plug in the wall to momentarily turn the camera off..., then back on when he rocked forward. While I'm glad the fix was simple (moving the chair) it was utterly frustrating knowing it took years to find and affected 50-100 services.

[Warren Webb]

My 02 Ford Windstar's a/c stops blowing thru the front ducts (& sounds like it goes to the defroster) when engine is in a power mode yet all info I have says the ducts are operated electrically, not by vacuum, yet they seem to work as if they were by a vacuum.

[Bordeaux Daytona]

My 02 Ford Windstar's a/c stops blowing thru the front ducts (& sounds like it goes to the defroster) when engine is in a power mode yet all info I have says the ducts are operated electrically, not by vacuum, yet they seem to work as if they were by a vacuum.

They are vacuum. There might be a hose off under the hood or the sometimes the rubber part inside the front or rear function switches get gummed up inside and leak vacuum.

[Randy Bohannon]

Does it also blow hot through the defroster? Check the vacuum check valve in line with the vacuum canister. I'll bet it leaks.

[rkapteyn]

How simple our old Studebakers are Your turn the AC on and that is it.

[WinM1895]

So I know this is a brand "X"........but I know someone will have an answer I can understand.
The a/c and heater blower motor starts and stops depending on the relative position of the gas pedal..........so I know I have to find the vacuum leak, either the "coffee-can" is shot, the vac valve attached to the vac tree under the hood, or one or more of the hoses have cracks...........what I have trouble understanding is how can the blower motor which is electrical, stop, start, and run slow, depending upon the engine vacuum? In other words how can vacuum control an electric motor?

Thanks in advance for the education.

What year is the Crown Vic and which type of A/C does it have?

Manual integral A/C or A.T.C. (Automatic Temperature Control)?

ATC was troublesome to say the least, Ford did not supply parts for the dash parts, only thing available was the complete set-up and it was 'remanufactured.'

[Hawklover]

After lots of investigation I found that the large "coffee-can" (vac for a/c) had a hairline split in the top crimp.........that can needs to be able to hold 20" of vacuum for at least 60 seconds with zero drop............after pulling 20".......it dropped like a rock in 30 seconds. ATC is a real PITA...that and the stupid pollution pipes attached to the cats.......which always rot out.........those pipes are getting very hard to find...next time I toss em, along with the air pump.
On another note.....I was able to replace the complete exhaust system with an entire Walker exhaust......ALL MADE IN THE UNITED STATES of AMERICA!!!!!!!!!!

[Hawklover]

Getting the Avanti ready for the summer.......have to find the R-12 leak.........just picked up a full case of 12 one pound cans......e-bay is your friend:-)