1995 F150 Air Conditioner
 

Here's my problem and it has been doing this for 10 years.After driving around with the air on and then park and shut the engine off for an hour and restart the air it blows very warm air for about five minutes then cools off.I replaced the compressor three times,flushed the system,change the dryer,vacuumed the sys down,changed the pressure on the dryer switch twice , change the pressure switch on the compressor twice and it still does it.Could there be something in the vacum system causing this,like opening the heater door then closing it.I am at a lose.

Did you change the Orifice tube?
No the cold/hot door is controled by a cable and not vacuum.

Changed it three times.

What are the low and high pressures when this happens? What is the vent temperature as well as ambient? Sounds like heat soak to me if the charge and pressures are in range.

Is the heat deflector material on the blower/evaporator case in place?

Low side pressure 30psi, high side 240 psi ambient temp 90 to 95 degrees.Heat shield in place on case, vent temp at 40 degrees.

Are those values listed when the system is working properly or after the heat soak?

The values are when it is working properly.

I am not trying to be an ass here, but have you checked the pressures and vent temps. when you say the vents are blowing warm air for 5 minutes after sitting for an hour or so? That should tell you if the compressor is actually turning on and working in the designed pressure range.

I go to work in the morning with the air on.When I get off five hours later ( I work part time ) start the truck turn on the air it blows warm.When the air starts to work the vent temp are cold,the same goes if the engine is off for only an hour or less.When I start the engine and drive off right away it only takes about a minute to start cooling.Also the compressor is engaged while it is blowing warm air.I ahve checked just about everything even the vacuum hoses.Like I said previously I changed the compressor three times and also the dryer.,pressure switches,flush system.This has been going on for ten years.I was thinking that some how the heater door is opening for some reason.
You are not being an ass,you are just trying to help me.

Mine is like that....Takes it a lil while, then it gets COLD....Personally, I would imagine some air in the lines would make it take longer to get the cold air pumping....Use a 4 way screwdriver, and bump the ball valve on the low side....If there is some air caught in there, it'll release it....Technically, its illegal, because it will also allow the refrigrant out too...

-Wes

I'll try anything at this point.

The valve will allow refrigerant and air both out...Push it in for a sec or two....See how that works....The refrigerant will start spraying out when the air bubble is gone...Just make sure not to breathe the air near the valve, because it will take you out FAST....And don't touch the refrigerant....

-Wes

Ok thanks.