Hi, I have a 1986 E 150 4.9 L engine. I replaced the entire A/C system about 7 years ago. I recently had a cracked line on the condenser. I replaced that, the dryer, the line coming out of the condenser to the expansion valve and the expansion valve, along with new o rings concerning those parts. Pulled a vacuum, etc. Here is my problem: the airflow from the vents doesn't come out with enough force. I have had this problem since I've had the van. There is a Max and norm on the slide control for A/C but there is no Max. I have replaced the blower fan and noticed on the fan speed control, there are three resistors, I'm assuming they are low, med and high. But there is no resistor for Max.
Any Ideas how I can get the fan's rpm's higher? I haven't seen a part for the speed control for the max setting for that van.
I was thinking of by passing the speed control and having a switch to run the fan full speed or put a resistor in the line.

 

Assuming it's the right (variable) blower motor (??) , then I'd be leaning towards controls -- those goofy old "circuit boards" w/ wire type resistors Ford used. I'd OHM out the discrete components on the "circuit board".................

Also, normally on the MAX type setting (most modern Fords) it simply changes the source of air (OUTSIDE vice CABIN).

 

Blower speed shouldn't change going from normal to max. It just changes the air intake source. You may have a door that isn't closing. I'm not sure on those years but usually you can get in the passenger floor board and see the door moving. The controls for the vents/floor/defrost may have moved (if cable) and need to be adjusted. You may be losing air to the floor or defrost.

 

Ok, I thought on max you should hear the fan blowing harder. I know on my car it does that. So, what would the air intake be on the max? Yes, it does have the wire type resistor. I installed a new fan a few years ago and I believe I changed the resistor too. I'm not sure what you mean by variable blower motor. I didnt have much of a choice when ordering one. Can you explain OUTSIDE vs CABIN?
How are the doors opened and closed. The control on the dash is cable but is a vacuum used? I know a lot of things on that year van ran on vacuum.

 

F350 and Spaznaut are both correct about inlet air...
The parts in red are the inlet air door, seals, and vacuum motor that opens and closes the door. The door is also known as Fresh Inlet Air Door because when the ac control lever is set to normal, the door is open and allows fresh air from outside to mix with the cabin air. When you set the controls to MAX, the door closes off the outside fresh air vent forcing the air in the cabin to be recirculated.

If you look through the grill in the blue rectangle while moving the ac lever from max to normal, like Spaznaut says, you can see the door opening and closing. Like they both said, you are just changing the source of the air. When on Max the door is closed and recirculates the cabin air which makes the fan sound louder hence you might think the fan is running faster.

I am not sure if it was you or another person but we were talking about installing a vacuum controlled heater valve so shut off the flow of coolant through the heater core. My 1988 E150 does not have one and the coolant continuously flows through the heater core. The heater core is in the same housing as the evaporator and I was told by a company that specializes in auto ac that by installing a heater valve, it would lower the AC temperature noticeably. He said that the only time the Fresh Air Vent Door is closed is when the ac is set to MAX. So he said to install the heater valve and for a vacuum source, tee off the door vacuum line to the heater valve.

Set the controls to defrost and cycle through the fan speed settings. You should be able to feel the difference in each speed setting.

 

Thanks for the great info and diagram. Very helpful, thanks guys.

 

Well if its not the air inlet door and you determine it has to be something electrical, let us know..

 

Okay. If the air inlet door is not opening enough, would effect the other settings, like the heat coming to the floor vent or the defrost? I notice that in the winter when the heat is on- floor, it doesnt come out with alot of force but it does get warm enough in the cab. The defrost blows hard from the defrost vents.

 

It sounds like yours is just like mine. When on floor, you really have to move your hand around down there to determine exactly where the flow is coming from!

 

Yeah, I do have to move my hand around to find it but it does get nice and warm, never had a problem there. I usually set it mix, so it comes out on the floor and defrost.
But the a/c vents never blew hard at all. I just noticed that the belt is a bit loose. I think it's supposed to be about 1/4" slack midway on the belt. Right now it's abut 5/8" slack, so I'm going to tighten it a see how it does.
Another problem is the a/c vent on the passenger side, no air comes out at all. There are 4 a/c vents, one far left side drivers side, far right passenger side and 2, one on top of the other in the center of the dash. They all work except no air coming out of the passenger side.
From the diagram you provided I can't see where the air goes after the heater core/ evaporator housing.
Why would air come out of the other vents and not the passenger vent?