A/C pressure question
 

2007 f150 lariat screw 145k
Air conditioning started to blow warm air lately, 60 degrees. Thermostat inserted in the ctr vent. I checked the pressures a few days ago and was getting 35-40 psi low side and 125 psi high side with an outside air temp. of 90 degrees. A/C set on max recirc. fan speed on high, eng. at idle. According to the temp/pressure chart my low pressure should be at 45-55 psi and high pressure at 250-270 psi.

So thinking the system was a little low I added one can of R-134 today. OAT 90 degrees and now my pressures are 39-40 psi low and 330-345 psi high, still blowing approx. 60 degrees out of the center vent.

Not sure what to check next. Was going to use a water hose and clean the condenser of a few bugs that I noticed when the hood was up.

Any suggestions?

you are now overcharged. Also, check your blend door operation, if the hot air is mixing over the evaporator cooling is very inefficient. I doubt the condenser is that clogged but cleaning will help. You won't go wrong following the pressure chart.

Ok, will get the a/c serviced correctly at shop. Evacutate, pull vacuum, service with correct qty of freon and then troubleshoot the blend door.

I had a 1998 Navigator with a blend door problem that I fixed back in 2005. On that vehicle you could hear the blend door flopping from one position, full closed to full open. When it went to the closed position it blew full heat out the vents and was usually associated with when you stepped on the gas too hard.

Are these blend doors known to fail on these model trucks also?

Yes they are. I believe I am on my forth actuator. They are electrically actuated as opposed to vacuum. PITA. First three under warranty. Forth cost me ~$330 I think at stealership.

Update: I took the truck over to my friends shop to have the A/C charged properly and found out I had a blend door issue. After charging the system to the correct specs. it still put out approx. 55-60 degree air from the vents. The blend door wasn't closing off the air flow from the heater core side of the plenum with the temperature set at max cold 60 degrees. All I did was change the temperature all the way to full heat let it stay there for about 10 seconds (air coming out the vents then was very warm/hot) then go full cold. The temperature then started to drop to 40-42 degrees out the center vents.
I will probably wind up replacing the blend door actuator in the near future if I ever have this kind of temperature disagreement again.

Oh you will. Sometimes you can rest the blend door by disconnecting the battery for a system reset, but ultimately an actuator replacement is in your future.

There is a tiny plastic gear on the blend door motor. That is what usually fails. A 25 cent piece of plastic that requires hours of labor to fix. Hmmmm I wonder if Ford knew this and did this to drum up service dollars?

If you replace the motor put some grease where the door rubs against the plastic.