Is there any way the front blower can be wired to run or spin FASTER? The rear blower in my 1997 spins fast enough but the front could use a 5th speed. I have interchanged blowers and Resistors from rear to front, but no change, both resistors and blowers are identical. I remember one time a residential a/c tech showed me how to rewire the air handler blower in my apt. to make it run faster and the result was amazing, though he did explain the life of the blower would be shortened, I never had any problem. Does the same principle apply to a 12V automotive blower? Thanks for any tips.

 

No, I don't think you can rewire the simple DC blower motor to run faster. You can do that with some AC motors, depending on their design.

What you can do is make sure that the air doors are opening completely, so they're allowing all available air to go through. I recently found 2 broken vacuum lines in my AC control circuits. It did the usual switching to the defrosters when the engine was under heavy load, but it did not allow full flow, so it felt like nothing was coming through anywhere while the engine was working hard, and making no vacuum. Fixing those lines got the air flowing again.

 

thanks, I did start today to replace those plastic tubes at the plenum. I just feel more fan speed or air volume is needed in the front vents, the rear is fine.

how difficult is it to remove, clean and lube the under-behind dash air doors? I bet they are full of grime and slow to open or close. This is one job I have never tried.

 

If the lever on top of this can isn't in this position, the door isn't in the full A/C position and you won't get the full air volume you should. Also years of dust flowing over a wet evaporator builds up a crud that not only restricts air flow but acts as an insulator hindering transfer of cold to the air. I was completely amazed at how much more air and colder air coming out the vents became when I had to change a leaking evaporator on my 87. Outlet air temp in the low thirties in the morning and no problem getting down to 40 at the hottest part of the day. Fan will blow you into the back seat. Ha ha.
When you swapped those fans did you clean out the air box as best you could?
I pulled the fan and cleaned it out on my 97 and used some fin cleaner I got from O'Reilly's It made quite a difference.
BTW, changing the evaporator on an Aerostar is not that difficult. It's all done from under the hood. Edit that can is located on the engine side of the air box.

 

I did clean out the "plenums" when fans were switched, vacuumed thoroughly.

the valve in the picture goes up or down when MAX air is selected or deselected at the dash switch.

I replaced one of the brittle vacuum tubes with rubber hose. The problem I am having is trying to follow the two (black and white) tubes that go into the plenum through the rubber grommet, I tried looking under the dash but I cannot see them anywhere, I even removed the glove box for better access, I do see a vacuum connector with a RED vaccum tube of a different diameter, then there are white and black vacuum tubes but they go down, not up.

 

you could try a relay.

 

Second zenish suggestion of a HD relay 30amp and minimum 12ga wire from battery source thru relay to blower motor.

First, try a new motor. May be old worn out bushings, corroded cooked windings, these run continually, anytime key is on. Best to get a new high quality Motorcraft if you can find one, best 100% pure copper and high quality oil for life bushings.
Mine still blows like a wild banshee after 20 years, built Ford Tough?

Looks like most of the old Motorcraft parts have been dumped onto ebay

 

Be sure the blades on the squirrelcage blower fan are completely clean. A little build-up on them will ruin air flow over them and decrease the amount of air the fan delivers.

While you've got the fan out of the housing, be sure the face of the coil is as clean as you can get it to allow as much air through it as possible. I've thought about using a garden hose sprayer to flush it out but have never tried it. It will make a mess so be ready to catch the water with a bunch of towels under the glove box.

Bypassing the resistor and wiring the fan motor direct will allow the motor to turn as fast as possible.

 

Unless you have a voltage drop at the fan motor connection, you're not going to get the fan to run any faster. So, the only other reason is something restricting the air flow.
Use some A/C fin cleaner, follow the instructions on the can. You have to let it sit a few minutes, then rinse it out with a hose. Rinse it out, don't spray water under pressure in there. It will force the crud deeper into the fins. There was enough in the can to do this three times. The water won't go in the car, it will run out the drain. I also removed the resister pack while doing this.
I'm sure you've already done this but DFord is right. Clean the squirrel cage.

 

ok I followed the advice, removed the air filter box and ducting, the fan, the resistor, even the vacuum tank, then I kept going removing most all bolts around the evaporator cover, untill I got to the clamp screws holding the accumulator, very difficult to get to in 100 degree weather, so I did next best thing: used a garden hose through the resistor hole and fan hole, lots of leaves came out, I just kept hosing off every way I could, I even got my hand in there, and left the evaporator as clean as I could, at least the part of the evaporator I could see.

it would have been nice to remove the evaporator cover and do a more thorough cleaning but I think there are screws at the very bottom of the cover that are invisible and I didn't want to force it off. I can try in fall when weather is cooler and I have more info, the accumulator is in the way.

the squirrel cage was clean, no grime. but I brushed it anyway. The rubber drain tube from the fan motor to the evap cover was clogged with leaves. How did they get in there?

note that the whole exercise was because the vacuum tubing was all brittle and cracking and needed to be replaced / spliced / inmediately.

Jaguar uses similar plastic vacuum tubing (behind the dash, not in the engine compartment), and I remembered I had a/c parts from salvage XJ-6 and bang!! I had Red and White tubing which I used to splice the vacuum lines.

the picture shows the finished job after everything was back together with new vacuum tubing. Not a difficult job to do, now I want that evap cover off to clean that evaporator reall good.

Result?? the dash vents airflow has definitely improved, it was the leaves and grime over the evap. No wonder I could smell a certain "earthy" odor sometimes, now I look back and it was a leaf odor. How do they get in there?

I have plenty 30amp relays so I will give that idea a try later.

 

The air intake to the blower is through a "chimney" that fits to a hole in the cowl area. That area is covered by a plastic grill above the hood. It has small holes that small leaves can get through.

On my other cars where that grill is easy to remove, I have paced window screens underneath to trap leaves and smaller debris. About once a year I would have to pull it out to clean off all the trapped crud.

The grille on the Aerostar is much more difficult to remove, so I've never done that on that car.

 

you mean the black plastic Cowl grille? I can remove mine easily since I eliminated the rivets and now use screws. Good idea to screen the cowl grille from behind, I will do it.

 

"The rubber drain tube from the fan motor to the evap cover was clogged with leaves."

That's not a drain tube. It's an air flow tube to cool the fan motor.

The screws at very bottom of the cover are just like the ones on the top and side and can be reached with a long extension and socket, but I don't know if the cover will come off with the accumulator in place. The cover and lines are the only thing that holds the evaporator in place. If you get that cover off, I'll bet you will see a lot more crud on the evaporator.

 

It's much easier to take the cover off after loosening the accumulator.

What's the best way to remove those rivets without damaging anything? Do you use a pin punch to push out the center pin of the rivets?

 

thanks for clarifying the fan motor airflow tube, fortunately the motor is good and clean, and it is a Motorcraft motor.

So if I remove the two accumulator Clamp screws, I can slide the cover out??

I don't want to run the risk of forcing anything and disabling my a/c which is working great now, the airflow has improved after cleaning and replacing the plastic vacuum tubes, even the idling is now more stable. Amazing what a little silly tube can cause.

To remove the cowl grille rivets, I used a thin Awl tool, (my electrical tester is great). tapping the center pin down, and saving the "anchor". (it's the same principle as a wall anchor where the screw expands the anchor).

Then I went to a salvage yard and pulled the square plastic anchors found behind each tail light assembly. Then I went to ACE and found short but wide screws that screw into the plastic anchors so they fit tightly. I used the rivet "seats" as washers for the new screws, cutting off the long stem.

NOTE: I did have to use a drill bit to enlarge the oblong holes in the sheet metal under the cowl grille and the rivet "seat" holes so I could tap the anchors in place and run the screws through them. Lot of steps but I can remove the grille easily now and clean and lube underneath. The reason for square anchors is so they do not move when you tighten the grille screws. If you remove the 4 screws at each taillight assembly, you will see the cream-color plastic or nylon anchors I am referring to.

Going to use your idea of a window screen over the chimney.

Thanks all for your help.