[A56Nomad]

Confused: The A/C on my wife's 2004 Ford F150trk w/60k miles has started to lose its cool, not warm, just not as cool as it was.
I tested the psi and temp before starting to get a base line, the high was about 200psi, the low was about 40psi, the temp at the register was 54 degrees F and it was 82 degrees outside.
I just placed one can of Freeze and one can of 134A.
I placed the Freeze can into the low side first and the high pressure went to about 245psi and dropped slowly to 210 again, I then placed the can of 134A and the pressure went up about 5psi and went back to 210psi and stayed there. When the motor is revved up to about 1500 to 1800 RPMs the high side goes to about 250psi and the low drops to about 25 to 30psi, the temp at the register is staying at 52 to 55 degrees F.
Sounds to me like a leak at the 215 psi level.
Tomorrow I will clean and air blast the radiator and the condensing coil at the front and try it again.
Any ideas with this A/C unit?

[41willys]

Check the evap to see if there is any debris or dirt build up. See a lot of plastic bags sucked in as well, causing the same concern - normal pressures, freon level o.k. etc, just not cooling.

Give that a look.

jason

[MAUSS]

Sounds like you overfilled it... the capacity is only 33oz total and you put in 24 more when it probably still had most of the charge in it. Why the heck are you using Freeze 12 in a system that's designed to work perfectly well on R134a? Freeze 12 is a R12 replacement. Vacuum it out and start fresh with the right volume of pure R134a.

[A56Nomad]

Mauss
This can of Freeze was 134A, you could be right about over filling the system. It worked OK today. Still can't figure out why the pressure on the high side went down when I added the two cans of 134A.

[75gmck25]

Most of these R134 systems are very sensitive to the right charge amount. I have a very non-standard retrofit in my '75 pickup (some old, mostly new parts) so we had to experiment to find the right amount of R134 when it was first converted. With the "right" charge I have 35 degrees at the vents (outside about 85-90), but with a 12 oz overcharge it only achieves a 55 degree vent temperature.

Bruce

[T-bucket23]

If this has a clutch fan, make sure it is working properly. We have seen this a few times as well as partially plugged as mentioned above. You can prove it by cooling the radiator and condensor with a water spray or an auxilary fan in front of the grill.

Chet

[carsavvycook]

Chet has it right. This is the way to diagnose airflow problems, whether it be by a fan clutch, or electric fan motor. You could just have a bad cooling fan relay, or blown fuse.

Your system is most likely over charged, at this point.

Look for dirt accumulated around any of the connections on the system. Also check the compressor. This will help to point out any leakage in the system. Whenever there is a leak, oil comes out of the system at that point.

Recover the freon, and find the fixed orifice. Pull it out to see if it has any debree on it. If so the compressor is going bad.

Hope this helps, and good luck.

Stephen