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2008 F150 uncomfortable.

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  • #16
    If you want to try pipe insulation is cheap enough for a test or just feel the temp of the line how much it warms up after the "O" tube. I don't think hardware store pipe insulation should be left on not rated for engine compartment heat so would take it off and just test that. Still - you should feel that or if in doubt just touching try an infrared, touchless thermos I use two all the time but need something solid or go erratic,
    Tom
    MetroWest, Boston

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    • #17
      Originally posted by Bob F. View Post
      Well, the liquid line is fairly hot. The orifice is close to the condenser and then aluminum tubing with a short hose and more tubing into evap. I can't see how this would NOT be absorbing heat. Especially with the excessive heat in the engine compartment. Ford built it this way. I would think the orifice needs to be closer to the firewall. I drove the truck early this morning and it did great. 40°F in just a few minutes. By noon it was back to 48° and 50°.
      The liquid line being "Hot" tends to contradict the high side pressure reading of 200, which would equate to 130 deg, so may be you are not condensing. 130 deg while above ambient wouldn't feel "hot". Much better performance in cooler temps also tends to point the same, that is too much heat, not enough cooling in the condenser. Hot with low pressure could be compressor, or low charge, but both of these you tried to address with a new compressor and measured recharge. Adding a condenser fan was one idea to see if it helps, but didn't.
      The refrigerant must go through a "Phase change" from gas to liquid and back to gas, for there to be any capacity to the system at all.
      I would expect much higher pressures if the outlet (liquid line) is hot. The pressure/temp chart is a great help here. A hot (170-180 deg) liquid line, one would expect to see pressures in the mid to upper 300's. It is possible to have high temps and low pressure but the refrigerant would remain in a gas state in the "liquid" line.
      I am at a loss to explain what you are seeing. I guess the 1st thing I would do, would be to run with a set of gauges on the system and a thermometer in the vent and mist or spray the condenser with water and observe the gauges and vent temp. The high side shouldn't dip much below the high 100's (psi) if the outside temp is near 100 deg even when misted. I am at a real loss to explain the low high side reading when combined with the other symptoms. AN internal restriction ahead of the high side tap could throw off readings of what the "true" high side pressure is could be a possibility
      Back on post #4 Tom suggested that the high side was too low. If the liquid line is hot, I would agree with Tom. Your high side pressure equate to 125-130 deg, or about 25 deg above ambient which would be suspect when combined with your "hot" liquid line.

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      • #18
        OK then,, Tom and Cornbinder89,, I'm going out this morning and start this over again. I know what's going to happen but I'm goin anyway. I'm going to hookup to the pickup and run at 1800 RPM with 3 marks on the blower speed. Man, this pickup has a rotten AC. I'll get back to you. FYI,, Ignacio told me to check orifice for leaking or in backwards. Not in backwards but a little loose when I put it back in. Thanks guys.

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        • #19
          OK, so I didn't do that yet,, It is now 85°F in Amarillo, at 10:00 A.M. I got in the pickup and went for a drive. Around the neighborhood down the street etc. Pickup was at 42°F vent temp in just a few minutes. Took it down a main 4 lane to I-40 with the same result except it pulled down to 40°F. Got on the Interstate and drove just a couple of miles because I saw it drop to 38°F which is what I have the adjustable pressure switch set on. Unit performed acceptable. Now here is the problem. When the ambient temp crosses 90°F. The AC in the pickup will NOT be able to cool the interior. I'm going to recommend a dash cover because I really don't know what else I can do. The AC unit is working. You guys have anymore thought's ?? I can hook up to it and see what it's doing but the fact is,, It's cooling. I'm open for any suggestions or comments.

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          • #20
            Lost with this: How can you produce 42F vent temps and not cool the interior? Windows left open? Is this the large 4 dr. cab with front A/C ducts only rear should still be OK just not as good. Same with the vehicles Suburban sized front air only fine if first two rows if a third seat doesn't cut it.

            Yes to dash mats premade for just this and floor mats too meant for the vehicle. Shouldn't have to but paint just roof a reflective color, window tinting as legal and so on.

            The #1 question is what the heck are you using for a thermometer and how do you know it's right or even close? Same for ambient temp - don't go by what a rear view mirror or dash says as that's a forecast knowing where you are not what the vehicle is exposed to in many that signal is picked up from air waves date not real for the vehicle.

            Highways? Black asphalt or concrete? Changes everything.

            With that performance if true higher speed vent center temps it's behavior is simply under powered BTU wise for the vehicle or overcome by invasive heat in or interior air out way too much,
            Tom
            MetroWest, Boston

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            • #21

              Originally posted by Bob F. View Post
              OK, so I didn't do that yet,, It is now 85°F in Amarillo, at 10:00 A.M. I got in the pickup and went for a drive. Around the neighborhood down the street etc. Pickup was at 42°F vent temp in just a few minutes. Took it down a main 4 lane to I-40 with the same result except it pulled down to 40°F. Got on the Interstate and drove just a couple of miles because I saw it drop to 38°F which is what I have the adjustable pressure switch set on. Unit performed acceptable. Now here is the problem. When the ambient temp crosses 90°F. The AC in the pickup will NOT be able to cool the interior. I'm going to recommend a dash cover because I really don't know what else I can do. The AC unit is working. You guys have anymore thought's ?? I can hook up to it and see what it's doing but the fact is,, It's cooling. I'm open for any suggestions or comments.
              Why do you have the cycle switch set at 38 deg? You want the low side to be 28-32 degs (24.5 psi to 27.8 psi with R134a) there is always some temp difference between the refrigerant temp and the fin temp of the evaporator. Basically, you want it as cool as possible without the condensate freezing on the evaporator. By setting 10 deg hotter, you are reducing the effective capacity of the system.
              Also check the system with the blower on high, with it turn down, the vent temp will be cooler, but if it can't cool at higher air flow no one will be happy with it.

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