Hello everyone! I just got my A/C fixed and blowing cold yesterday. I've never had it running since I had the truck, only the heater. My question is, when I put it on MAX A/C it doesn't blow any harder than the regular A/C. I thought it was supposed to but I wasn't sure. I thought MAX was for re-circulation and normally blows harder (more air velocity) than normal A/C. It's that way in most of the Fords that i've been in. Am I crazy here? lol.

Does anyone have any suggestion on what could be causing the problem? I know that under the hood, there is a vaccum actuated plunger right above the blower motor. I switched the setting between MAX and NORM but the plunger didn't move on it. I moved it by hand with my other hand in front of the vent and it didn't seem to make a difference at all. Does anyone have a diagram of the vents and blend doors and what they do? Also, what would be the easiest way to access the evaporator to clean it. I'm sure that it is dirty and that would definatelly free up some air flow. Thanks in advance!

 

MAX A/C never changed how the blower motor ran.
The idea that MAX gave more air comes from the fact that you are not pressurizing the cab when using MAX.
Next time open the windows and try both setting and you will see the same amount of air come out of the vents.

That said the vacuum motor on top of the Heater/AC box should move when going from outside air to inside air (MAX). This is the only difference between MAX and Normal A/C modes.




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I figured that the motor didn't change speed, although just by the path being shortened (from outside to re-circulate) it would free up some power of not having to draw the air so far and give you a bit more velocity. I've heard a change in sound in other vehicles (can't hear mine because of the exhaust) that just might be the sound of the blower motor reflecting off of the blend doors. It makes sense that the pressurized cab will slow the motor down a bit. Either way, I don't think that I can pressurize the cab. lol. All my window and door seals are shot and need to be replaced. Also with the fan on HIGH and the mode **** on MAX A/C, the airflow was a bit lacking. I might have a weak or plugged up blower motor. Do you know the easiest way to access the evaporator for cleaning?

Ok, i'm going to have to look into this then. The vac line running to it looks a little brittle and might have a hole somewhere. I know that it didn't move between changing modes. Looking at the diagram that you provided, it looks like there is a line coming from the check valve into the control panel (the piece with all the *****). I'll see if I can pull it out and check all the lines. I have to change an instrument cluster light in that panel anyways because it's half dark at night. Thanks for the quick reply SUBFORD. As always, you help is greatly appreciated!

 

Good info from Subford.

To gain access to your evaporator you will need to remove the screws on the engine side of your evaporator box. This will allow the side of the box to be removed thus allowing you access to the evaporator core, however, you will not be able to remove it as it is connected to your accumulator at the top. You will need to remove your blower motor and then you can clean out all the leaves and debri that has collected over the years. Although harder to do without removing it, you can clean the evaporator from the motor side with some 409 or a good cleaner and a good blast with a wter hose. This is a good time to also clean your blower wheel which will help your air delivery.

 

Thanks redlightning93! That was the extra info that I needed. I just might have a bit more room to clean it also as the truck has a body lift. I work in the HVAC field and have some pretty good foaming coil cleaner. As long as the evaporator isn't deteriorated, i'll try to use some of that on it also and maybe i'll shoot the condenser while i'm at it. I'll take a stab at cleaning the blower motor while i'm in there too. I'm also thinking ahead a bit and am going to check the condition of the evaporator. If it's pretty clean and clear, i'll know that my blower is getting old and weak and it's time for a replacement. I'll let you all know how it goes. Thank you guys a bunch!

 

I don't know if you fixed it, but my outside vent actuator wouldn't work either. When I operated it by hand with the fan running I was able to tell that the outside air was shut off (bottom of windshield). After checking every vacuum line inside the cab I realized it was the white one in the motor compartement that was leaking. Rather that replace it, I was able to cut the dried portion off, split back the wire wrap going into the cab to get some slack, and reattach it using the same rubber boot. Works like a charm now.

 

Time for an update! Did I ever mention how much I love A/C in Florida!! lol. After a few set backs (like losing the rubber gasket in the high side schrader port cap and leaking the majority of the freon out) I have it charged up and running great. I had a free gift card so I just went ahead and ordered a new blower motor from RockAuto.com. Figured with as many miles that are on the truck, it was time to replace it (I believe it was the stock blower motor also). When I took the blower out, I seen that the evaporator was all junked up with leaves, twigs, dirt and dust. How would all that get into there? I can understand the dirt, lint and dust but I thought the screen on the cowel kept all the leaves and twigs out of there. No wonder it wasn't getting good air flow! So I did what redlightning93 said and removed the evaporator cover on the engine side and sprayed the crap out of it with a garden hose. I didn't need to use the foaming cleaner or 409, water worked just fine in taking the crap off. I had to scoop most of it out of the blower motor side.

I put the cover back on and the new motor in and fired it up. I used the diagram that subford provided to help me out with what vents did what but the recirculating vent still wasn't working properly. I cut the conduit that covers the white vaccum line back a little and found another hole in it from being dry rotted. I took out some slack and redid the connection. I verified that it had good vaccum but it still wouldn't operate the vaccum motor. It was really sticky so I think that i'm going to have to order a new one. I used a zip tie to lock it in the re-circulate mode for the time being. I had it running for a bit while I was under the hood on MAX AC and HIGH fan to let the truck cool down. Well when I went to jump in the truck, I think I sprained a nipple! Needless to say that it's working way better than before. I wanted to thank you guys again for all your help again. I love this forum