My other problem that has reared it's ugly head on this trip is that my AC blower just goes weak after awhile on the road.
First, I just had this engine replaced, and I have talked to the mechanic and been reassured that he properly recharged the system and saw no potential AC problems. He said everything was great, and he's a trustworthy guy.
When I'm on the highway, my dash vents just get weak over time, and my interior temp (aftermarket digital temp gauge) will rise slowly. If I shut the van off, or switch it over to defrost or floor and back, sometimes it will come right back to full strength and interior temp will drop quickly, down to 74 degrees measured at the headliner level when it's in the 90's outside.
I'm sure most will guess this is a blend door problem, but I haven't taken it apart yet. My questions are, How deep is the blend door/mechanism on the vans, do I have to pull the dash or anything? Also, could this be a relay or other electrical problem?
Also, the van has factory rear air. It ALWAYS blows strong and cold, no matter what the front system is doing, so this narrows things down for me.
Thanks

 

Crack a window open so the system can equalize the interior pressure.........

 

I have, it makes no difference.

 

The A/C heater control panel switch is vacuum operated (green&tan) w/ac, yellow&tan w/out, might be leaking off changing door position. Belive it or not I made your controler @FOMOCO.....LOL

 

Ha, really? Are you a retired or current Detroit man? That's pretty cool.
I see what you mean by seeing if a pressure change/window crack would help, I though they were vacuum controlled, or maybe just electrically controlled. Either way, that doesn't help. Do you know how deep the blend door mechanism is? I'll be taking it apart when I get home.

 

Well I did see a Dorman replacement blend door @ like 200.00 bucks so use care! You have 2- Black switches for on/off fan speeds (front/rear), 1- Green/Tan vacuum valve for function, 1- Blue Potentiometer that controls the blend door (hot/cold) The Valve will dryrot over time and let the other doors get out of place, or the Potentiometer can get a dead spot in it...or the door motor. Most Econolines were made on afternoon shift in small runs along with F-150,Ranger,heavy truck,Dodge Viper, good times! But I'm glad to be retired after 2 days of 100+ degs here in Mich...........

 

hmmm, interesting stuff. What's weird here is that I've had LOTS of cars, and I can usually feel a blend door/valve problem just by the feel of the ****, but this one feels fine. Smooth and sure operation, no hard spots at certain places or on certain functions. I'm curious to see what I could see if I could get to the door and operate the switches while I watch the door work. I have had one or two of these apart and I know that some are impossible to see since they are encased in a plastic box or the like.

 

After reading some other posts recently about AC problems, I'm thinking this may be a vacuum issue. I realized more also that I don't just have an "air blowing" problem, I've also got a "air temperature" problem. My van just won't cool off at all while stationary, so It's possible I have a freon leak, but could I if it cools off good after you start moving? Also, rear air still blowing cold so freon leak doesn't make sense.
Can anyone post a diagram of the vacuum lines/diaphrams/etc. I should check out, or give me their exact locations? I have an electrical manual for this van but not a full servicer manual.
thanks

 

What year is your van? I can post a diagram of the AC vac system.

 

Thanks, that would be great. It's an 02 5.4 passenger van.

 

95e150CW might have something more helpful but try these in the meantime Scotty:

 

When the airflow gets weak is it blowing out of other places, such as the defroster? If not, then I think your problem may be the evaporator icing over. If the A/C system gets too cold the evaporator can fill with ice, which reduces the airflow.

 

JWA, sweet! Thank you! I'm gonna look in to this problem tomorrow or over the weekend, but I'll update as soon as possible.

Mark, thanks also. When the airflow gets weak, I can hear it moving in the box under the passenger dash/footwell area. I can turn it to max ac and hi and it sounds like a tornado over there under the passenger dash. I can sometimes get full airflow back by toggling the selector switch a couple of times, or simply turning the unit off for about 1 minute. That's why I have thought I have a blend door problem. It seems to me like the air is getting caught somewhere between the box and the dash vents. BUT, I still am losing temperature somewhere as well. It used to get cool at idle and much colder moving, and now it doesn't get cool at all until WELL after I'm moving. With the weakened airflow, sometimes it's almost useless.
Also, I have NOT done a simple freon check with a gauge yet, but I don't think that's the problem since my rear air blows steady, good and cold, and doesn't go away at idle until after sitting awhile.

 

Scotty I had this same issue of changing temperature only mine was during winter---heat suddenly brrrrrrrrrr cold! I eventually discovered the dash temp control was also acting intermittently and sending the wrong signal to the blend door motor.

Should you need to change the blend door itself here is something I added to a thread some time ago: https://www.ford-trucks.com/forums/9...r-problem.html It might be helpful if its not the other suggested things.

Blend doors aren't impossible, just take a bit of forehand knowledge.

HTH