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2008 F150 uncomfortable.

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  • 2008 F150 uncomfortable.

    2008 F150 Supercab, 5.4 engine
    Truck has had a AC cooling problem since before new owner bought it.
    He took it to a repair shop where it got new compressor, new condenser, orifice tube and accumulator.
    Daytime ambients are 95 and 100°F.
    Also new blend door actuator and crimp heater hose shut. This truck has to be driven 3 miles on the interstate to get it to cool down to 45°F. Compressor is set to cycle at 42°f. So it doesn’t ever cycle. The AC never gets the interior of truck even comfortable when driving in town. Stays around 60°F. vent temp. I added a pusher fan on the front. Did not help even a little. In the shade at 1800 RPM the high side is 175 to 200 psi. Wait several minutes and low side will finally pull down around 30°F. I can run the blower no higher than 4 marks on the display. That is a medium low speed.
    Takes evening temperature drop to get the compressor to cycle.
    I taped my digital thermometer leads on the inlet and outlet at evaporator. I got consistent 46°F.into and 44°F. out of evaporator. Low side at 30 psi. I was able to get a hole in the case and slide a thermometer into the fins of evaporator.
    The temps are around 47°F to 50°F or more. Could the evaporator be coated with something inside? Maybe a hole in the hvac case? If so,, I cant find it. I can’t remember not being able to get a truck to cool. I have a 2000, F250 and a 2011, F250. Both do a fine job. I put pusher fans on the 2000 model and it will cool 40°F all the time. Even in this 100°F degree weather. All other Ford trucks I've worked on do not exhibit this behavior.

  • #2
    lets break this down a bit. Highside shows a condensing temp of between 120F and 130F which is not bad (with 95 to 100 deg ambient) so I think we can rule out a condenser problem. 30 PSI low side says a evaporating temp of about 35 degs, so that looks right. Not cycleing only tells you the heat load on the evaporator is enough to keep the gas pressure above the cycle point.
    Since this has been a long term problem, that points less and less to refrigerant amount being the problem, but not definitive.
    If turning up the fan (air flow) seams to make the problem worse but if it doesn't show an increase in the temp of the outlet line from the evaporator, that points to air bypassing the evaporator. Temp reading of evaporator fins will always be higher than the tubes or refrigerant in the tubes, just as the opposite is true at the condenser.
    Pinching off heater hoses will not completely stop flow in the heater in most cases, a little gets thru. It might be worth shunting the hoses and takeing the heater completely out of the question, if only for a test. If doing that causes no change in the temps than I would be looking hard at air flow and the possibility of air bypassing the core.
    It is possible that there is something inside coating the tube and reducing heat transfer, but it seams you are getting some and have relatively good heat transfer at the condenser,


    • #3
      Ok,,, I agree with you. This might possibly indicate the truck has had service in the hvac case or even from the factory. I've read numerous stories at the Ford Forums about this identical problem. I have not read any solutions. Possibly requires Dash removal??? I've kinda run out of ideas.


      • #4
        Quote">In the shade at 1800 RPM the high side is 175 to 200 psi.<"
        That was at 100F real temp not a forecast meaning air entering thru grille?

        That's too low. Problem you said from new not pleased does make it tricky. Yup - there can be heat intrusion from new or assorted reasons even color of the paint. Vent temps near always rise a few degrees from the actual evap temp just thru ducts. Notice this with center vent vs a side vent particularly driver's side a lot more loss of cool.

        If you trust you temp observations vent temp if really recirculating seems fine to me at a real 100F.

        IDK - at a glance seems like a tad more refrigerant would help not that much. Since new and again with the parts listed new should rule those out now if replaced with a system working just not happy with it?

        Hard call. That's hot and 3 miles of highway driving if entire interior is hot takes a while which 3 minutes if say 60MPH.

        Works fine when cooler out? How big is this cab? 4 dr?

        You put "pusher fan" in that it didn't have. That just makes me question if fans are fighting with each other such that density of air is inadequate but pressures don't seem to reflect that?

        Alright - I'm stuck on this complaint from new still the same so either design from new wasn't adequate, refrigerant charge even listed isn't correct or heat is getting in somehow where it shouldn't.

        Are floors hot to the touch, air felt coming in thru door handles inside?

        Not sure as the vent temp is OK with me pressure seems low high side higher than I'd want low side so still thinking.

        1. Wrong charge amount even if on an OE sticker somehow? Accumulator on this should be cool just to touch or sweating if enough humidity not close to warm as leftover charge "accumulates" there is inconsistent with evap temps in and out seem perfect being that close to equal.

        Brain twister - something isn't right from new I'm stuck on. Ford is very strong with Truck designs IMO. Is owner particularly fussy? Comparing it to another is hard to match up some may be 4X4 or not and airflow out and how much heat thru firewall and floors different.

        So - If equipped to try I'd first look for insulation missing even if from new. Next - cool condenser with water or whole truck's body too if a wild change condenser fans are not flowing enough air for some reason. That could even by a plastic air dam under front bumper not there for its looks can (rare) allow engine heat back up and thru grille rather than flow down and out broken new or missing from new still pressures don't add up totally so if equipped would go 2oz up in charge at a time and try to duplicate same drive and hope same conditions to see if better, same or worse. Tweaking it I'll call that. Takes time with same conditions. You know if it is just that you get worse performance right when you pass the right spot/amount of charge if you can go back and mark the truck with then the known amount,

        MetroWest, Boston


        • #5
          Tom, I've run the charge up and down along with driving and a helper holding RPM's. the problem is only cool air at low blower speeds regardless of charge. On medium or more blower speed the vent temps do not drop below low 50's up to 60's at traffic signals. A Mom carries around a youngster in a child seat. (fiy) The truck also got an E-fan clutch which may or may not be working ok. However, service manual says don't change it unless the check engine light comes on with a code. I emailed Nacho and he said they have had the same problem with this model from another shop. They pulled that one apart and flushed it out again and started over. I'm going to start this over and see if any change. I know these pickups should be doing better than this. It's really hot in the cab and just does not cool down at all. The fact is,, When you assemble an AC unit on a vehicle. You should be able to charge it up and have it cool the occupants. This truck does not come close.


          • #6
            I will defer to Ignacio, as he has much more experience, and on that make/model than I. Please, please report back on what you find and if you have success.


            • #7
              OK: You've been in touch with Nacho and he had the same complaint sent to him I can't compete with volume I know he would have and consistent hot weather to deal with so please let us know what he did or found. I'm lost with the observations and history of this since new catches my attention. That suggests under full warranty nobody made this right.

              FYI on dealers and problems from the get go. The manufacturer pays to fix once at their set rates for what was found then about all back off and the dealer owns the problem without some very aggressive contact with the right people in this case Ford they are credible with what they did and problem isn't fixed going into recall mode which is the last thing manufacturers want.

              Good grief if the mainstay of Ford, the trucks and F-150 in particular made it under par for this model and just blew it off IMO it's suicide for them to ignore but might because it's just A/C not a flaw causing accidents, fires and safety issues just move on and tick off a few customers.

              Again - please say what Nacho comes up with for a cure for this. I doubt he'd let it go till a fix if possible was out there.

              Your #s and performance are not acceptable to me. If that's normal for a line guess we need to know and what the fix now 10 model years later is going to be most likely by now at the consumer's expense and a lot of help from the pros. Good luck,
              MetroWest, Boston


              • #8
                I had a thought last night. What if the compressor is "weak" but not totally FUBAR? Say a leaking reed valve? the effect would be reduced flow/capacity. Everything would "slow down" and explain the "good" heat transfer at the condenser and reduced capacity of the evaporator. It would explain the hiway cooler readings.
                I know a new compressor was tried, but???


                • #9
                  Good thought. Was compressor new or a reman job?
                  MetroWest, Boston


                  • #10
                    The compressor is brand new. I've had the same thought. I read these articles in the Ford forums dated back in 2008 -2010- 2012 etc. Exact problem and the writing said the dealers were saying Ford said 20° or 30°F below ambient was acceptable. That is baloney. I'm starting this truck over and I'll try warranty on any questionable stuff. I'm new to these E- Fan Clutches. I question whether this one is doing the job. I'll get back to you guys when I make some progress. Also, The guys who put this thing together are very competent. They worked on and off for 3 weeks trying to get it to cool.


                    • #11
                      I know nothing of the Ford E clutch but I had one car that had an electric clutch and it worked just like a compressor clutch. No matter if it is not moving enough air over the condenser, you would expect to see the high side rise and the outlet of the condenser get HOT.
                      Last edited by Cornbinder89; 07-04-2017, 10:10 AM. Reason: spelling


                      • #12
                        Hmmm - does the clutch work at all or somehow seem weak? Funny but not a joke it's listed in stock for a heavy duty one not the OE one suggests it's a problem!

                        Like anything pricey sucker @ about $250 wholesale not really surprised at that.........

                        Pic if it shows>
                        Image of Duralast Fan Clutch : Part number 922120
                        MetroWest, Boston


                        • #13
                          OK,, as per Nacho,, I pulled the accumulator. I flushed the condenser and got clear fluid back out. No signs of oil. So clean I could reuse the stuff. Then flushed the evaporator. This time the clear flush was slightly cloudy. That would indicate only an ounce or two in there. I've been driving this pickup around and it hasn't blown up. OK, so I put it back together and added 8 ounces of oil. Then took it out the highway. Didn't really change much. Ambient was at 100°F. Later the sky clouded up and ambient dropped to 92°F. I took the truck out and kept it on city streets. It was holding around 40°F to 48°F. I'm just gonna quit there. I don't know what else to do. I was thinkin maybe the liquid line is absorbing to much heat before entering the firewall. Long stretch of aluminum. I may do that but I'm fairly sure it won;t help. Give me your thought's if you wish. Thanks for the help friends.
                          Last edited by Bob F.; 07-04-2017, 09:12 PM.


                          • #14
                            How hot is that liquid line? According to your condensing pressure it shouldn'y be too hot, I know some have the orifice tube in the outlet of the condenser, they say it doesn't matter but it would seam to me, anything on the low pressure side should be insulated until it reaches the evaporator.


                            • #15
                              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°.
                              Last edited by Bob F.; 07-05-2017, 02:23 PM.


                              • #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,
                                MetroWest, Boston


                                • #17
                                  Originally posted by Bob F.
                                  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.


                                  • #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.


                                    • #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.


                                      • #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,
                                        MetroWest, Boston