'05 F150 STX 4X4 4.6L EVO and Gotts

The air from my air conditioner changes temps, from very cold to cool. You can really tell the difference when it changes but right away it gets cold again. Is this normal? I drove my wife's Outback today and it did the same thing. Seems odd that they would both have the same problem so I thought I would ask if this is the way they are made now.
I should clarify that it cycles; cold, cool, cold, cool, cold, cool, etc. and the duration of the cycles is short, less than half a minute.

 

Are your cool concerns when the truck is at a stop, idling? If so, this is normal, as not enough air is flowing by the AC condensor when stopped/idling. The fan cannot pull enough air through to cool down the condensor. When driving, the AC should be cold, as plenty of air is flowing through as you drive forward.

 

No this happens while moving, all speeds, highway and town.

 

May needs to add some R-134a into the system.

My wife's fusion was doing the same thing and I added a can of 134 and it fixed the problem right up.

 

Before adding freon, get the system checked. You do not want to overfill the AC system, as this can create failures. The "do it yourself" kits they sell these days are misleading; they make it sound as if freon simply "wears away" or "drys up" and requires periodic refill. Not so. It's a gas/liquid, and is only lost if there's a leak in the AC system.

Get it checked.

 

I dont want to start another A/C thread, and I have been searching trying to find the answer that I need. I have searched and found that I should be checking the low side while the engine is running, with the max A/C setting. I also found that I shouldve bought a high & low manifold tester, as I only have the gauge for the low side. But as I continue to find answers to solve my problem, can I ask the following:

1. I do not have bugs on my radiator, but should you use some sort of brake cleaner to get rid of dust/dirt/residue on the Condenser to enhance the heat exchange?
2. Should their be a hissing sound coming from the A/C after the truck is turned off? I am almost positive that its the A/C because if you leave the gauge on after you turn off the engine, the pressure rises.
3. And should the low side's pressure increase when the engine is turned off?

BTW, the low pressure side measures in the low 30's when it was 95+ degrees outside. I know I could go up to 45, but I am not sure how much one can would add. The truck blows cold air, but it will usually be warm when it first starts and sometimes blows warm during idling (I know that that's normal down here). But it never blows cold enough so I have it on Max, Recirc, full fan and that is why I am trying to find solutions.

 

You're doing some great research; hats off to you!

I can only answer one of your questions, the one concerning cleaning the condensor. No need to clean "dirt" from it unless it's caked on from four wheeling, just make sure that bugs, leaves and such are off of the fins. Whenever I wash my truck (two to three times a week), I open the hood and use a soft brush to wipe down the condensor/radiator area. Be carfull to not seperate the fins from the tubes, as this is how the heat from the tubes in both the AC condensor and a radiator remove the heat from the liquid in the tubes. If I find any bent fins, I carefully use a small flatblade screwdriver or small needle nose plyers to straighten them out. One person told me they use a fork to "rake" the fins, but I don't like that idea, as it can break the fins from the tubes.

The other questions I'll leave to those that have that experience/knowledge about.

 

my truck has always "hissed" when i shut it off. not sure why it does it, but it and all my other vehicles have.

the second question, i asked the dealer when i bought my off the shelf walmart 134a refill kit if it would work when i had my ford tbird and he said you have to make sure the car is running, preferably with someone else behind the wheel giving it just a little gas (keep rpms just above idle, around 1000 or so) to get a good "fill" with one of the DIY kits. If i remember correctly, he said something about not connecting it until the vehicle is running because the pressure reading can be higher than it actually is unless its connected after its running. he explained that it had something to do with flowing pressure instead of static pressure, but i was only 16 at the time and dont really remember lol.

 

Thanks Bucko! I wish there was a sticky or at least a section in the "Suggested Threads" sticky since this seems to be a big topic.

I definitely do not see any blockages and its been over a year since I last went muddin. No bent fins so thats fine. I hope someone else has some input.

 

your A/C Compressor is cycling on and off and thats why it is very cold then cool. There could be a few reasons that cause this...your low pressure switch has failed, If you dont have the proper oz of free-on in the system and that can also cause your compressor to cycle. Only real way to find out is to get it checked out.