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Poor A/C vent temps in 2007 f150 Pages: 12

scumfrog on Thu July 24, 2008 9:27 PM User is offline

Year: 2007
Make: ford
Model: f150 lariat
Engine Size: 5.4L
Refrigerant Type: r134a
Ambient Temp: 95
Pressure Low: 40
Pressure High: 225-230
Country of Origin: United States

I have been fighting poor vent temps in my 2007 f150 for months now. All the dealers say that all aspects of the A/C system spec out normally but when it is 90 degrees or hotter outside the best vent temp I get is 52 degrees. I can be driving and the vent temp can read 52 and then all of the sudden the temp will go up to 58-60 and you can feel it get hotter. I leave a themometer in the vent all the time so I see this happen. It is like the compressor shuts off but it isn't even cool inside yet. In the morning after the truck has sat all night and the outside temp is 75-80 when I drive to work the vent temps will get down to about 42 degrees. The vent temp will never get this low once it gets hot outside(85 or more). I am very frustrated because I need the 42 degree vent temp when it is hot outside not when it is 75-80 degrees. My wife's Sable vent temp will be 40 degrees after driving for 15 minutes in the same heat. I have been told that the hose going into the heater core should have a valve put in it so you can close it and keep the hot coolant from getting to the heater core. It seems to me that something happens when it gets hot outside and then the vent temps just won't go low. I don't know why the vent temp can get to 42 in the morning and won't in the heat of the day. I really would appreciate any help because I am totally exasperated because the dealer and Ford are saying everything is fine but I know it is not cooing properly. I can't seem to get any help from them. It is still under warranty and only has 6000 miles on it.

Chick on Fri July 25, 2008 7:00 AM User is offlineView users profile

You could have a wide clutch gap causing the clutch to take longer to cycle back on at hotter temps. Check the gap for .02 also you may have a bad cycling switch. You need to find out what pressure the compressor is shutting of at. Disconnect the blower and run the AC on MAX with gages on and see what the cycling off/on pressure is. You might need to find a shop that can do better diagnostics

Email: Chick


Freedoms just another word for nothing left to lose

GM Tech on Fri July 25, 2008 8:21 AM User is offline

Even poorly designed systems can cool in the morning- this is why shoddy shops always give back the cars first thing in the morning- they have time for the customer to get home before they hear the complaints..-- the 42 vent during morning is very easy to get- the ambient is less- think about it- you have to draw in 70 degree air- knock thirty degrees f out of it and shoot it through the vents- all in one pass- with very little contact time in that evaporator-- then when it is hot out say 90 degf ambient- you do the same thing and expect the same 42 degf vent temps- I don't think so.. more like 52 degf at high blower. A lower blower motor speed always creates cooler air- due to the time it has against the evaporator core- so you guys with thermometers in your ducts can soon understand this- and how it works-- also when you are driving and you see the vent temp go up and down- you are reading the results of a compressor cycling on and off- to avoid freezing the evap core-- this is good- the last thing you want is a frozen core- because it will get really hot inside when that happens.. When it is warm enough out that the compressor runs continuously, that is when the vent temp will stabilize- and that is under high heat load.

As long as the cycling switch is good, the condenser fan is operating correctly, the refrigerant charge level is good, there may not be too much else to expect---

Your comparing your truck's a/c to a car is not fair.. many people try to do it-- they are completely different systems, designed completely different and will have wind tunnel results differently-- you need to compare your truck's a/c to another like model truck- not a car. A/C systems are the last thing designed in a car/truck application-- people want styling first-- styling sells, not a/c!! Heck I could design an a/c system that would freeze you out- but it would look like a box and nobody would buy it. That truck you have was designed for function- to pull and haul, not to keep people happy inside that drive them to work everyday...although they try-- a good example- is why don't they use dual electric fans on the condenser- like cars do? this is part of the design/styling/function decisions made by car and truck makers every model....Trucks never cool as good as cars-- period.

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

NickD on Fri July 25, 2008 9:34 AM User is offline

Ford has been half way decent in the past about specifying vent temperatures versus ambient conditions that include both temperature and relative humidity. Ask your dealer to read is shop service manual.

On the other hand, you can go nuts reading a thermometer in the vent of your vehicle, move that back to where you and your passengers are sitting, or better yet, are you comfortable? Don't buy a Caddy, mine would really drive you nuts, can ram the temperature control between 60 to 90 or vice-versa, Caddy doesn't want grandma to feel either hot nor cold drafts. But if you set it at say, 67* F, that is what the inside car temperature will be after a few minutes.

scumfrog on Fri July 25, 2008 11:34 AM User is offline

Thanks guys a lot for the great info. Would I be helped to put in a dual Flex-a-lite e fan? They make one for the f150s. What about putting that valve in the heater core hose to decrease hot water going into the core area of the cab which then causes hot air to diffuse into the cab? Does this make any sense?

NickD on Fri July 25, 2008 1:33 PM User is offline

What about putting that valve in the heater core hose to decrease hot water going into the core area of the cab which then causes hot air to diffuse into the cab? Does this make any sense?

It does make sense, but many of the newer engines depend on the heater core circuit for engine cooling and closing that circuit may cause hot spots in your engine that will burn it out. That would have to be very carefully checked out. In the older engines with heater valves, take off point was the thermostat housing, return back to the low side of the radiator where the core was effectively in parallel with the radiator. If the return is going back to the engine manifold, heads, or block, then the engine depends on that coolant flow for cooling, but this is only a general rule. Can be something going on the inside that is not obvious.

Making any changes to your vehicle can void the warranty whether that change caused a problem or not. Believe that Brad had problems with an Explorer a coupler of years ago, maybe he can comment.

GM Tech on Fri July 25, 2008 2:13 PM User is offline

The valve he speaks of has its own bypass- or at least it should--

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

NickD on Fri July 25, 2008 2:43 PM User is offline

You mean a heater core bypass, don't you? DeVille has one, my old Fords didn't and this is assuming his still uses a blend door. Was trying to list a precaution, never looked at a 2007, but probably will in 2017, ask me then.

The easiest way to test this without cutting hoses is after a ten mile drive, switch off the AC if on, switch the climate control to the vent position and with his thermometer compare the vent temperature with the outside temperature after stabilizing, if the vent temperature is only a couple of degrees higher, fooling with the heater core won't make any difference.

May have misread your post GMtech, by meaning to add a shutoff valve with a bypass on it. But if the vent temperatures were much greater with the AC off, think I would be knocking on the door of my Ford dealer. They have had blend door problems in the past.

Edited: Fri July 25, 2008 at 4:06 PM by NickD

scumfrog on Fri July 25, 2008 4:42 PM User is offline

Nick, I will do the highway test and compare the vent and outside temps. What about the e-fan, are these worth the money?

scumfrog on Sat July 26, 2008 3:45 PM User is offline

Nick, I tested as you asked but am still confused. After driving for 15 minute I shut of the A/C, put it on vent only, the auto temp was set at 60(but again A/C was off), and when I did this the vent temp was about 85 degrees and the outside temp was 95 degrees based on the truck's outside temp gauge. Does this tell you anything?

scumfrog on Sun July 27, 2008 8:03 PM User is offline

Guys I am really confused. Today it was 97 degrees here in Oklahoma. I get in the truck and it is about 120 degrees inside the cab. I roll down the windows and drive a few miles to air it out. I then set the A/C on 60, recirculate, high fan and then after driving 10 minutes, the cab is not cool at all at this point, the vent temp is only 54-55 and the dang compressor shuts off, then the vent temp quickly shoots up to 60, and the air coimg out of the vents smells like I had just switched off the recirculate. It smelled like outside musty air. Now, why would the compressor shut off before it reached peak cooling? I can now tell exactly when this is going to happen because I feel a change in vent temp and then immediately smell outside air. It seems to me that the cycling of the compressor is not in sync or something. I am at a total loss how to get the dealer to help me and Ford customer service has already done nothing but say they believe the dealer. On a hot day at this rate the cab will never cool. I have owned many vechiles in my life and this is the most frustrating thing I have ever gone thru.

iceman2555 on Sun July 27, 2008 11:00 PM User is offlineView users profile

This may be a bit redundant...but has the system been serviced....has the refrigerant been recovered, system evac'd and recharged to insure that the system is completely charged. A simple pressure test may not indicate this problem. Suggest to have the system recovered...the amount of refrigerant removed should be weighed and compared to OE specs for this vehicle.
Once the recharge condition is a few simple test...max cool...high blower...engine at idle...cabin doors open. Engage compressor and allow the system to stabilize...this may take a few minutes.....measure the inlet and outlet temps of the evap...should be almost insure that the system is completely charged.....test the inlet and outlet temps of the condenser....should be about 25-30 degrees difference....just to check for a possible problem there. Measure ambient temp...about 12-15 inches in front of the condenser and compare this to center vent results.
The outlet temp of the evap...prior to entrance of the accumulator should be a good indicator of the temp of the this to the vent temp....a normal difference between evap temp and vent temp may be as much as 5 degrees or more. If a the temp difference is indicated between the evap temp and center vent temp....then a possible blend door or other air delivery problem maybe evident. A leaking blend door with a full time heater would be indicated here.
Once the system is determined to be completely charged.....the two heat exchangers are operating as they should....the close the cabin....max cool....blower on 2 or third speed...elevate the engine rpm if desired.....allow the system to operate for a time....monitor vent temps....and low side pressures....the LPCO should cycle the compressor at app 22-25 psi....the compressor should re engage app....40-45 psi. This cycle should continue unless the air flow (blower speed) in increased or decreased....decreasing air flow will result in a more rapid cycle point.
The post that the system cycles off at highway speeds with a possible high temp load is a bit concerning.....could be a possible LPCO problem...this should not occur unless the evap temp/pressure is below the 25psi range. Could also be a possible high side pressure (discharge) problem. Does this vehicle have a 'high pressure relief valve' or an HPCO switch?
The LPCO should not disengage the compressor with a high heat load....max cabin.....high vent temps.....
It is always best to run the A/C in 'norm' mode until the cabin temp is less than ambient temp......then change to 'max' setting...this will cool the cabin much more rapidly.
Even if the vehicle is 'new' is still most important to know that the system is fully charged......and the best method.....get it all out...and recharge once more. If I were a betting man.....the dealer is simply testing pressures.....and temps....and making a determination that the system is functional.
Try the max cool..high blower..engine @ idle...doors open....test the evap inlet/outlet temps....this will indicate a possible undercharge condition. If the inlet is cooler by more that 8-10 degrees than the evap outlet....the system is probably undercharged. With the smaller charge rates of todays vehicles...the amount of refrigerant within the system becomes much more critical for total system performance......gotta be fully charged....!

The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

NickD on Mon July 28, 2008 12:48 AM User is offline

Nick, I tested as you asked but am still confused. After driving for 15 minute I shut of the A/C, put it on vent only, the auto temp was set at 60(but again A/C was off), and when I did this the vent temp was about 85 degrees and the outside temp was 95 degrees based on the truck's outside temp gauge. Does this tell you anything

It's telling me you have automatic climate control and either you didn't give the evaporator enough time to warm up or the compressor is still engaged. Thinking about my daughter's 1998 ZX2, that is a Ford Escort, it's manual with a multi-function mode switch, as I recall, only two positions on that switch turned off the compressor, off and heater, when placed in vent mode, the compressor would come on again. Have the shop manual on this thing, and the compressor does come on in Vent mode just like it does two clicks CCW on that switch in AC mode. Wonder what Ford was thinking? Maybe they are doing something like that with yours, why have a vent and an AC mode that do exactly the same thing.

See Iceman is suggesting to have your refrigerant level checked, never hurts, but could be an ATC problem as well, as you did report cold vent temperatures. Thing is, if you set your temperature to 60*F, vehicle should be at that temperature at the center of the vehicle, regardless of what the vent temperature is. If that is varying, could be an in-car sensor problem, poor contact and earlier Fords, in the late 90's had a warped blend door problem, cheap plastic, but I thought they corrected that.

Another test is to ask your dealer to test drive a vehicle like yours and see how that reacts, my Ford dealer is decent on adjusting complaints, small town, better or they will tar and feather him.

I did have problems with my 04 Cavalier with zero play in the clutch and got tired of hitting my nose with my knee when shifting, went to my Chevy dealer, dey all do dat. Found another, TSB on that, replaced the master cylinder with a newer style and that cured the problem, have to be insistent, but some people you just cannot deal with.

befuddled on Mon July 28, 2008 11:29 AM User is offline

Knick, you have jogged my memory. I had a town car once with the automatic climate control. I did not think thye put that in trucks. Anyway, there is a filtered air inlet on the dash. It is about a half inch high, and an inch wide. It connects to a hose that connects to a pump the side of a pill bottle. this air circulated over the temp sensoe in the AC control head. I do not remember just what the malfunction was, but I replaced thee pump/hose assembly, and all worked well after that. The symptoms were somewhat similiar to yours. If airflow is blocked in this hose, the AC will go beserk.

scumfrog on Mon July 28, 2008 1:30 PM User is offline

Yes it does have climate control. I can tell you the cab temp never gets to 60 when it is set on 60. I have it on manual setting, 60, recirculate and the best the cab temp ever gets is at best 70-75 and that's on a good day. Should I run it in auto setting and recirculate? I know in my previous Aviator when it was set to 60 and on auto setting it would blow hard until the temp got down and the fan speed would then automatically slow down. If I set this truck on auto it will blow high fan forever and never slow down.

NickD on Mon July 28, 2008 4:57 PM User is offline

You convinced me you have an AC problem, now if you can convince Ford. Small claims court always seems to work.

scumfrog on Mon July 28, 2008 7:12 PM User is offline

Nick, that is the problem. Ford and the dealer say it is fine. I have had it to the dealer 3-4 times and it is the same story each time. All is in specs, pressures, etc etc, recharged it, new orifice tube, etc etc. So I call today to tell the service manager that it still does not cool and told him again everything I have posted here and this was his response. " I took another f150 out today and the best vent temp I got was 54 degrees". Now this was after I had called him and talked to him this morning and so he drove that truck and then left that message on my phone. I guess his point is it must be normal since the other f150 does the same thing. Ford has a mjor issue with their f150s and they will do nothing. I checked the inside cab temp(thermometer in cup holders behind the center console box) and it was 80 degrees after drving for 25 minutes, and all the settings as I described above. That is why you can go on the internet and find so many guys doing mods to their systems like putting the valve in the heater core hose. It is so sad when the consumer just has to bend over and take it. Ford sucks and I wll never own another one that is for sure.

NickD on Mon July 28, 2008 7:38 PM User is offline

Now they all suck, Ford, GM, Toyota, and Honda, while the latter two have a couple of small vehicles, they also have their share of large trucks and SUV's, and none of these are moving with the high price of gas. Did have problems with my Chevy dealer, refusing to give me my usual discount, wasn't that much so paid retail any way, charged service appears to be their only way to stay alive during this none-crisis crisis.

Question for you is what do you want to do, live with it, or make modifications if you can't get Ford to fix the problem. First step is to find any TSB's on the problem for other hints, my Ford dealer will print those out for me yet. Can ask yours, also has TSB's but have to check if your new vehicle is listed first.

Then there is scanning for codes, some ATC systems let you get in, others require a scanner, basic OBD II scanners do not get into the MVAC system, more expensive ones have a so called Ford option software package, this would have to be learned.

In the system, extremely major to make any modifications to the evaporator cooling circuit, it's size, or the blower motor, compressor is normally okay leaving just the condenser and how it's cooled. If you can find somebody that went through this, and what improvement were made, would save a lot of effort on your part.

Hate to say this, but it's best that you know what you are buying before you buy it, some states do have lemon laws that provide another avenue of attack.

scumfrog on Mon July 28, 2008 8:19 PM User is offline

Nick you have been so kind to answers all of my questions and I thank you for that. I do have another one. If I set the A/C to auto, 60 degrees, and recirculate so that it is all automatic settings, shouldn't the cab temperature get down to around the 60 degree mark? The climate control automatic digital setting is set to get the cab temp to 60 and not the vent temp to 60, correct? It seems to me that this is the literal meaning of a climate control system. My A/C at home sure gets to the digital setting I have set it to.

NickD on Mon July 28, 2008 10:47 PM User is offline

That's exactly what it should do, vehicle temperature should meet the digital set temperature. If you have 600 CFM of air movement with even a 57*F vent temperature in a 120 CF vehicle, that is five complete air changes per minute or one every 12 seconds, that should keep you cool. What is your cab style, single or double seating.

How is your vent blower strength? Powerful on high speed? Realized this is a subjective question, but weak blower speeds with some kind of restriction will not give you a cool vehicle.

See you posted your pressures, really don't look too bad, was that at an engine speed of 1,500 rpm, blower at max, AC on, and the doors wide open? Want that baby to work. Is the compressor running continuously at those conditions? Better be. Bit tired now myself, but thought I read where the orifice was changed, maybe on a different thread, is this a CCOT system with a cycling switch and a high pressure cutoff switch? I noted you stated the compressor is switching off with that musty odor, something is switching off the compressor. The method here is to drive the vehicle with the pressure gauges attached and taped to the windshield so you know what's going on. With GM that I am more familiar with, can do that inside of the vehicle by watching the climate control low and high side temperatures as displayed on the screen.

Thing is, it's a brand new vehicle under warranty, in my case if not happy with my Ford dealer, there is another ten miles up the road, I talk to them. And much better to talk to a mechanic, the service managers don't get into these details and manage more than fix.

Something is wrong.

scumfrog on Fri August 01, 2008 8:49 PM User is offline

Yes blower strength is good. Nick, if I get in the truck at the end of the day and the inside temp is 120-130 and I roll down the windows for 1/2 mile, air it out, set it on regular air not max and then after 5 minutes set it to automatic climate control at 60 degrees, when would you expect the cab ambient temp to start dropping? What temp would you expect the A/C to be able to blow out of the vents at that point? I would think it should be blwoing at least 50 degrees by then and the compressor should never cut off during this time. My compressor will cut off several times during this time period and vent temps never get close to 50. I called the dealer again and the service manager told me he would not call the regional service engineer rep because the pressures were good. He said if the pressures are good nothing can be wrong. Isn't this a bunch of crap? Pressures don't equal a good system do they? Can other things be wrong that could affect cooling even if the pressures are normal? I really have no place to take the truck to. No A/C specialists that Ican find even exist in Oklahoma. I would take it to an A/C guru if I could find one but none in Oklahoma that I can find.

scumfrog on Fri August 01, 2008 10:09 PM User is offline

Nick or GM Tech. When it is 90 plus degrees outside, fan is on high, cab is not cool at all but yet the compressor cycles off and does not run continuously isn't this wrong? Shouldn't the compressor never cycle off until the load on the A/C is lessened? If it didn't work this way, it would seem the car would never cool well. Am I wrong in thinking that the compressor should never cycle off until the load has been reduced?

scumfrog on Fri August 01, 2008 10:17 PM User is offline

Iceman in your post above you state that if you were a betting man you would bet that the dealer is simply checking pressures ans saying everything is functional. If you see my post above that is exactly what the service manager told me today. Yes, the compressor is cutting off under high heat load. The dealer told me that all the cycle swtiches are pressure activated if that helps. If you need more info please let me know.

iceman2555 on Fri August 01, 2008 10:29 PM User is offlineView users profile

Unfortunately, you are stuck with a moron....operational pressures are good....what the heck kinda of statement is that? Pressures are only good when one factor is truly much refrigerant is in the system. It was stated that the system had been serviced...evac'd...etc...when a service mgr makes this would place serious money on the fact that this statement originated from one of the 'techs'. Makes one wonder if the services claimed were actually performed? Stranger things have happened.
For you there is a simple test....simply operated the vehicle...make a couple of temperature test....try max cool...high blower...doors open....engine this in manual mode with the system set for maximum cooling. Test the inlet and outlet temps of the evap.....if the system is fully charged...the temps will be the same...or within 3-5 degrees of each other. At least this test will remove one of the variables...a properly charged system.
Since the vehicle is within warranty....does your state have a 'lemon' law....or perhaps a road trip to another city....another dealership.....for a second opinion.....sure beats being stuck with a vehicle that will not cool properly....esp with the drop in value of these trucks.
The A/C system should produce temps in the low 40's until the cabin temp reaches the desired setting. The system should adjust itself between Max cool/Normal cool dependent upon ambient temp....cabin temp sensor.....and if equipped....sun temp sensor.....the fact that the system cycles is a possible indication of low charge....or....a ATC control problem

The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

scumfrog on Fri August 01, 2008 10:51 PM User is offline

Iceman, how do I take temp readings of the evaporator? Where is it? Where is the inlet and outlet?

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