How to bi-pass low-n-high? '86 MGM Tudor

[Toploader]

How would I go about getting my blower motor switch to run only on high, and not on low or medium?

[gadget73]

flip it all the way up ?

[JeffBoudah]

Turn it to 11

[Toploader]

Gadget I do not want the switch to "see" either low or medium.....I want it to be operated only in one position...fast. Ok, I have this problem the blower motor slows down at certain times when in a/c mode or heater mode....I changed the blower motor, and the resistor, and the vac tree on the dash, (no change) when at speed the damn thing just stops, and then maybe thirty seconds later starts to blow again! I have a new blower switch that I have not put in yet....when my bud put one of the vac testors on the coffee can he claims it holds with no leaks??? I just want to make certain it is the switch or the coffee can.

flip it all the way up ?

[Bobcat]

Automatic temperature control...?

[sly]

replace the AC check valve at the firewall. Motorcraft YG337. It's not holding vacuum in the system and allowing the vents to drop to the floor. The blower might be limited due to the blend door position due to the lack of vacuum as well.

[gadget73]

If you slide the switch all the way up, it will not slow down. It only does that when set to "auto". If you're losing air, its not anything related to the blower at that point. If you want to bypass all of the wiring entirely, just connect the black wire at the blower straight to ground. It will run full speed all the time with no control. It may not even turn off, not completely sure if the climate control will break the hot side when set to "off" or not.

[sly]

the setup in the Mark would back it off even on high. It may be the same for ATC in the 86... which would be a vacuum issue. Possibly even the main feed line being crimped and in need of replacement like on the Mark.

[lincolnlarry]

I would put money on the switch or the connection from the switch to ground if the airflow doesn't change to the floor. When either of the two flake out, the blower will run in low even though the switch is on high.

[Toploader]

Sly I already replaced that, no change:-( The blower motor is FoMoCo NOS....no change, and new resistor as well, and that YG337

replace the AC check valve at the firewall. Motorcraft YG337. It's not holding vacuum in the system and allowing the vents to drop to the floor. The blower might be limited due to the blend door position due to the lack of vacuum as well.

[Toploader]

But why does it return to high blower after like 30 seconds?...

I would put money on the switch or the connection from the switch to ground if the airflow doesn't change to the floor. When either of the two flake out, the blower will run in low even though the switch is on high.

[Toploader]

Gadget this situation happens even when the switch is in the manual high position and not on "Auto" with the slide set all the way down to 60 degrees. This is a frustrating situation....car rolling along and all of a sudden the blower motor stops blowing, and as I said maybe 30 seconds later it starts to blow again on high!

If you slide the switch all the way up, it will not slow down. It only does that when set to "auto". If you're losing air, its not anything related to the blower at that point. If you want to bypass all of the wiring entirely, just connect the black wire at the blower straight to ground. It will run full speed all the time with no control. It may not even turn off, not completely sure if the climate control will break the hot side when set to "off" or not.

[sly]

NFC - I'm at a loss here

[87Topaz]

Gadget this situation happens even when the switch is in the manual high position and not on "Auto" with the slide set all the way down to 60 degrees. This is a frustrating situation....car rolling along and all of a sudden the blower motor stops blowing, and as I said maybe 30 seconds later it starts to blow again on high!

I would check out the vac lines going to the TBL. That's what the problem was on Bobby's GM!

[gadget73]

If its cutting in and out completely, thats a different problem. Sounds like electrical gremlins somewhere in there. If the blower motor resistor plug is shaky, that might explain it. The connections at the blower itself also get bad. Its a high current circuit, anything remotely questionable will cause problems. If you're hearing the motor go silent entirely, look at the electrical stuff first.

The TBL is only a factor if it does this in "floor" mode. That switch is not in play in any other mode. The vacuum section does cause leaks that shift things towards hot and to the defrost vent, but they won't kill the blower motor.

Small airflow changes are probably fresh air / recirc door action related. You can't manually force operation of that on an ATC system. When the blend door is at it's extreme, its in recirc, so the air door under the dashboard opens and pulls air from inside the car. If it moves just a twitch, that shuts and you get air coming from outside. Due to the way the air ducts are shaped, and because you're trying to shove air into what is essentially a sealed (albeit poorly) passenger compartment, its going to move less air than when its just moving the air in a circle. On the manual climate control, simply moving the selector from "max AC" to "normal" or whatever its marked as will control that door, and you'll likely notice the same sort of minor airflow changes. There is a definite noise level change there too, its louder in recirc (max) mode.