AC Issue

Ok I know thi shas been asked 10k times my AC just doesn't seem to be right. I just changed the fan clutch, and still have 45 psi on the low side at ilde I have a 97 degree ambient with a temp of 71 at the center air outlets, when I rev the truck up to say 1800 rpm the low side pressure will go down to below 30 lbs and slowly come back. What the heck am I missing??? Driving down the highway it will cool but not freeze your ass out. I see guys on here getting 50 55 degrees discharge temps, wifes Pilot, is blowing cold as the day we got it, I just sold a 96 bronco that would make ice, I live in Miami, and going to a garage is a limited option, I have no idea who to trust down here. I could really use
some advice. I thought it may be a bad cabin filter, or a blocked evap, (air flow) how does one get to it to check????

First thing to check is the blend door. Make sure it isn't leaking some hot air into the system. Next would be the static pressure and ambient temp when checking along with the high side pressure when running. The low side is getting close to the lower limit if it is dropping under 30. This will cut out the compressor until the pressure builds back up.
Without knowing the static and high side pressure I would venture your problem is low refrigerant or a partially blocked accumulator.

wish i was up near you............

I was flipping the can of 134 around and noticed a charging chart, saw where they recommend 45-55 low side at 95 ambient. Now I got a 25degree spread but still warming at idle. any ideas gauges are now busted will have to get a set tomm. boy I wish I had that bronco ac system back.

Yes the weather was nice up here last week. Has been raining all day and forecasted to rain most of next week. Going back to hot and humid.

We need to know the high side pressure before anything else. Get a good set of gauges that are liquid filled. I started with a cheaper set from HF - ended up being a waste of money. I now have a set of spare hoses should I ever need them.

Have you added any 134 to the system?

Yes added gas

ok I got a set of gauges, at a 94 ambient, I have 248/54, at an idle speed of 650 rpm, this is in the sun with the sun blasting on the condensor, we checked with a digital temp, and the direct sunlight on the ground is around 104. I also noticed with the a/c on or off there is no change in engine idle, I looked it up and it says 550rpm is idle speed but it doesn't say what that idle should be with a/c running.
Question here is this, truck cools great on the highway, will go to 69 cycle on auto, buut when idling the temp sucks (goes warm) I know it should be related to the fan and air flow across condenser, when I increase idle to say 900-1000 it will cool better but not great, ok what am I missing? Could it be an air flow restriction across evaporator? Truck is 03, I am guessing there is a way to clean that evap without pulling the dash? or is my problem condenser related and I should start thinking electric fan? I really wanted to get my front seats recovered next but this cooling problem which seems to be getting worse and worse at idle needs to be addressed. thanks red423

Spray out the condenser real good. Bugs, dust and debris will reduce the air flow. Is the fan shroud intact? The shroud forces the fan to pull through the radiator and condenser. Even one piece missing will reduce the air draw.

Check this site for pressure / temp readings.
R134a Refrigerant Pressure Temperature Calculator

With the system being at idle for a few hours, take a reading of the static pressure - do not run the system. This will tell you the ballpark amount of refrigerant that is in the system. At 94 you should have slightly under 115lbs.

I prefer to run the low side in the mid 40's for pressure. Yours is high to me, your low side pressure will equal around 57 degrees - check with the thermometer on the lines going into and out of the accumulator, plus the accumulator temp.

Has any 134 been added to the system? Make sure the fan clutch is working, if it isn't the pressures will rise and cooling drops off.

thermostat?

I just saw these messages today, I have a few minutes this a.m. and will blow out the condenser with a water hose, pressures stay intact, if I go to less than 54 low with this heat we been having I loose cooling except at highway speed. I will clean that condenser and get back to ya'll, the shroud is intact,, seems to be cooling a bit better since I added gas, it will cycle on auto if i run down the road a couple miles and it runs really well in the evenings and at night, it's that blasting Florida sun during the day and red lights which seem to handicap it. Thanks for the help, I 'm a going to try the above and get back to ya'll red423..............................

Red is the air colder from the rear AC outlets than from the front vents ? Just wondering because the rear has a separate evaporator and blend doors, this can usually help you diagnose some issues. If the temps are the same front and back then you have to look at the common component(s), such as system charge, compressor, condenser... . Here's a nice write up on general system diagnosis : AC system charge and diagnosis. You should check system pressures with RPMs stable at 1000. Are you the original owner of the truck ?


-Mike