I am having a nuisance problem. When you put ANY pedal into it, as in any off of idle, the a/c drops off the vents and onto your feet. Not a big deal in the winter as the heat is on my feet anyway, but with a/c weather coming its a huge deal. I pulled the line off the actuator and the actuator is fine. It doesn't leak either. There are no vacuum leaks. The vacuum at the intake port is fine too. I pulled the lines off on all sides of all vacuum check valves and they are pulling vacuum in appropriate places. I am at a loss of ideas here and it is becoming a huge nuisance. It just adds to it that I work full time and goto night class, so I have zero time to diagnose it. 15 minutes here and there is a pain in the butt. Is there any common points to look at or what is wrong with this thing...

 

CHECK THE BROWN LINE THAT RUNS INTO THE FENDER BEHIND THE BATTERY , THAT IS THE ONE THAT CONTROLS THE HEAT AC DOORS. MINE RUBBED THRU.

 

I don't have a leak, anywhere, interior or exterior, checked it. Tonight for my 15 minute wack at it I pulled all 3 check valves from the firewall, battery areas one at a time and blew in and out on them to check em. Two of the three were fine. The one that hooks to vacuum side, its checked, then it goes to the reservoir, and the line to the cab for the ventilation system. The valve was free and clear, but it wasn't checking the flow when the vacuum would drop. I shined a light in it and there was some debris in it (dirt looking stuff). I rinsed it out as best as I could with a combo of water faucet and blowing and sucking on it. NO COMMENTS GUYS!!! I put it back on and it worked like it should on a test drive for about 5 miles (in the hills, so varying throttle and vacuum). It quit working right after that, as in it went to feet and defrost under any throttle. So long story short, problem solved, it is the check valve, I'll just have to get a new one.

To edit: This is a salvage titled truck, which I have never been involved in. Haven't even come close to the value of a non-salvage truck with repairs, BUT the nit pick crap has drove me nuts! IF I wasn't capable of doing ALL my repairs on my vehicles, it would've come close to the value, but since I can, its not even close....

I would guess the dirt is from sitting in the yard between its crash and fixing up...

 

Close, the valve at the zone, Federated auto parts, NAPA, and Ford dealer were all to big on the vacuum nipple. I sucked and blowed on it again and it worked right. I put it back on and it dropped out after throttle. Looked at it again and figured out that the last person to work on it had plugged the lines up to the check valves backwards, in short, the resevoir was checked to the hvac system. So the only way it ever worked is that the third check valve was stuck open when I bought the truck, not stuck closed. When It started working correctly, the vents didn't. Now that the valve works and the lines are hooked up right it works perfectly. Here is what I wonder though. I used to get A LOT better fuel mileage than I have been lately, coincedence or something here? With the resevoir hooked where it was, the egr vacuum solenoid and the canister vent valve were getting FULL vacuum all the time, it should slowly drop when you lay the hammer down shouldn't it? Maybe that is logic for fuel mileage... I mean its a lot too, I drove it on the highway for a tank last summer and got over 19 mpg, fast forward to today, it is getting around 13 no matter how you drive it.... This thing is killing me, I am going to night class and traveling a lot, so a few more mpg at 4.00 a gallon would add to a lot. I filled it up after I fixed it, so I will post back my mpg now in a few days. FINGERS ARE CROSSED that it makes a large difference...

 

Thats interesting on the MPG, what engine is it? and will you keep us posted? You could be onto something with the MPG.

 

By the problem, not sure why, but it did increase the MPG a bit. I am now at 14.2. Still very sucky, but about a 1 mpg improve...