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Hello Everyone,
Yesterday I got my car back from the shop after having a water pump installed. So naturally since the cooling system was opened up I decided to check my coolant level once I got to work. I opened the hood and to my surprise one of my a/c lines were all frosted over.
Around this time last year I took the car in to have A/C work done as my compressor just stopped turning on. It was blowing very cold then I turned it off one day, rolled down the windows and a few minutes later rolled them up and turned the A/C back on to find it would not kick on and blow cold at all.
After the shop looked it over they found a faulty part somewhere under my dash that needed to be replaced (the name of the part escapes me, sorry) and when I got the car back, I had A/C but I noticed something different after that. After the A/C would run for a bit it’s almost as if air would stop blowing out of the vents. The only way to recover for this was to turn off the system and wait a while. Today however was the first time I ever looked under the hood while my car was experiencing this and I see the lines frozen. However I was not under the hood to investigate the A/C I was checking my coolant level and I found this nice surprise this morning. I have attached a photo. Let me know if you have trouble seeing it and I will try to get it to you by other means.
Thanks,
Brian
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Replies
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The blower needs to be running for the ac to work. can you verify the
blower speeds work. If the line is frosted the evap is probraly icing up
cutting off air flow. by looking at the picture I believe thats the suction
line. I would say you are over charged.[quote=”college man” post=97918]The blower needs to be running for the ac to work. can you verify the
blower speeds work. If the line is frosted the evap is probraly icing up
cutting off air flow. by looking at the picture I believe thats the suction
line. I would say you are over charged.[/quote]+1 This guy knows what he’s talking about. More information on AC can be found here.
http://www.ericthecarguy.com/faq/solving-automotive-hvac-problems
[quote=”college man” post=97918]The blower needs to be running for the ac to work. can you verify the
blower speeds work. If the line is frosted the evap is probraly icing up
cutting off air flow. by looking at the picture I believe thats the suction
line. I would say you are over charged.[/quote]The blower seems to work just fine in most cases. What I mean by that is when you first turn it on it works perfectly, gets nice and cold etc. After it runs a while it’s almost as if air pressure coming from the vents goes away. the vents on the dash are very cold but it almost sounds as if a fan is not spinning or not fast enough. Could it possibly be that I am having some sort of intermittent problem with the blower motor? It does do this also in the winter while using the heat but since components don’t freeze up from this in the winter it seems to have a faster recovery time (starts working properly again)
Again all of this, did not show up until after I had the problem fixed a year ago. Not sure if this has anything to do with it, but when my compressor stopped coming on it was right at the end of summer. Hot weather was done so I just never bothered to fix it since it didn’t seem to make sense spending a lot of money to fix something that wasn’t going to be used so I waited until spring of 2013 to fix it. Since then it has been doing this intermittent thing as described. Only today is the first time I raised the hood to find these frosted lines. Next time it acts up I am going to pull over immediately and look and see if it’s frozen, and when it’s working properly I’m also going to check it, I can get temp readings coming out of the vents with an infrared thermometer I have. If you have any questions I’m happy to answer them. I hope this is enough information surrounding the issue.
Thanks in advance,
BrianIf your not feeling air out of the vents. That would cause
the iced line. But with no air flow your low side pressure should
drop and the low pressure should stop the compressor. Hard to tell
without putting gauges on it to see what the pressures are doing.
If air flow does stop.You will ice up. verify that the blower does
stay on.if you can’t feel air then it sounds like the blower is
dropping out.On older cars with R-12 I used to love seeing the suction line frosted up. It was working at it’s best that way. I think college man is on the right track with what he is suggesting. Could be the compressor low pressure cutout switch is not allowing the compressor to disengage at the correct pressure or not at all. If it has been real humid where you live it will even be worse.
Connecting a gauge set will tell you if this is the problem. I believe the compressor should turn off at around 24 to 26 psi and turn on again around 44 to 46 psi with the engine running on low to medium fan speed.
[quote=”wysetech” post=98039]On older cars with R-12 I used to love seeing the suction line frosted up. It was working at it’s best that way. I think college man is on the right track with what he is suggesting. Could be the compressor low pressure cutout switch is not allowing the compressor to disengage at the correct pressure or not at all. If it has been real humid where you live it will even be worse.
Connecting a gauge set will tell you if this is the problem. I believe the compressor should turn off at around 24 to 26 psi and turn on again around 44 to 46 psi with the engine running on low to medium fan speed.[/quote]
Sounds like maybe I should take it to a shop. The day I snapped that photo was a very humid, rainy morning. You can still hear the blower when it acts up it just sounds muffled. What is the most likely bad part in this scenario? Compressor? (gulp)
No, The compressor is working fine. It’s the components that control the compressor are the problem. Possible low pressure cutout switch, shorted wiring or a control panel problem.
The compressor should shut off before the water condensing on the evaporator can freeze. If the compressor continues to run after the evaporator is below freezing the evaporator becomes a cake of ice and no air will flow through it.
the bottom line here is that the compressor is continuously running, that means the evaporator will not stop getting cold and will freeze and condensation on it. when all the ice is built up in the evaporator hardly any air will flow through resulting less airflow to your vents making it seems like the blower is not blowing but the air just cant pass. when the air cant pass the evaporator will freeze up even more because it does not get any heat to dissipate so even your low side line will freeze up. to fix this u have to look at everything that controls when the compressor shuts off, like the low pressure cut out switch or your thermostat in the evaporator, if your system in controlled by a hvac computer then it may have a temperature control sensor replacing the thermostat. hope this helps
There should be a temperature sensor embedded in the evaporator that lets the controller know that the evaporator has become too cold and it should shut off the compressor, so that the evaporator can de-ice itself. Then when the temp of the evaporator rises above freezing and the ice is melted the sensor sends a signal to the controller and the controller tells the compressor to turn on again.
Not knowing what kind of vehicle you have it is hard to be specific. This is how most A/C systems work. I think you probably need to replace the evaporator as I don’t think the sensor is available. You may want to go to a parts store and ask to take a look at at the replacement evaporator for your vehicle and see if it has a sensor in it. Also it would be a good idea to acquire a Factory Service Manual published by the manufacturer of your vehicle NOT Haynes or Chilton’s. You may be able to find vehicle info at your local library.
Hope this is helpful to you.John
I agree that taking it to a professional is probably the best course of action. AC diagnosis is best left to those with the tools and equipment to do it properly. Keep us posted on your progress.
[quote=”EricTheCarGuy” post=98334]I agree that taking it to a professional is probably the best course of action. AC diagnosis is best left to those with the tools and equipment to do it properly. Keep us posted on your progress.[/quote]
Oh I had no intention of trying to fix this myself, just trying to get a feel for what I’m in for. If it is this cut off switch that folks have mentioned, do I have to open the system? ie: evacuate refrigerant?
Thanks,
BrianFusion / Milan correct?
First I would follow everyone’s suggestion for proper diagnosis.
Depending on what A/C system you have, there is a TSB on this: A/C SYSTEM LOSES AIR FLOW/INOPERATIVE— TSB 09-18-11… which is reprogramming the A/C controller.
If you have manual control A/C the Evaporator the Discharge Air Temperature Sensor is in the top of the evaporator case and you have to remove the instrument panel to gain access.
This is a known problem with your vehicle and Ford is well aware these are faulty and I would push their button on this for repair.
[quote=”JTF” post=98541]Fusion / Milan correct?
First I would follow everyone’s suggestion for proper diagnosis.
Depending on what A/C system you have, there is a TSB on this: A/C SYSTEM LOSES AIR FLOW/INOPERATIVE— TSB 09-18-11… which is reprogramming the A/C controller.
If you have manual control A/C the Evaporator the Discharge Air Temperature Sensor is in the top of the evaporator case and you have to remove the instrument panel to gain access.
This is a known problem with your vehicle and Ford is well aware these are faulty and I would push their button on this for repair.[/quote]
As everyone is leaving their suggestions as to what the problem is and what to do about the problem (many thanks btw) it is reminding me of nuggets of information I initially left out.
Yes, it is a 2006 Fusion SEL V6 w/ Automatic HVAC
At one point the blower fan was suggested as if there is no airflow it will ice over. Well after closer inspection, the blower fan is not dropping out. it only SOUNDS like it is because it’s inside a block of ice. After turning it off a while it works normally. This morning on my way to work it started to act up, so I quickly set the temp to full heat and let it run a few minutes – that seemed to melt the ice and after a few minutes, when I tried it – I had AC! My point is, looking back at the blower fan and what I know now about air needing to flow, it is important I should note my AC does not do this if I leave it in full manual AC with the fan blowing full speed. The car has climate controlled/temp AC so if I let it “do it’s own thing” and decide fan speed and output vent – if the AC is on eventually it ices over because the fan isn’t running full speed. On really hot days I don’t even mess with it, I run it on full blast so I have AC 100% of the time. Also to note, this does not seem to happen at all when I just blow air through the vents (hot or cold) with the AC switched off. Again, thanks in advance.
[quote=”johnbkobb” post=98271]There should be a temperature sensor embedded in the evaporator that lets the controller know that the evaporator has become too cold and it should shut off the compressor, so that the evaporator can de-ice itself. Then when the temp of the evaporator rises above freezing and the ice is melted the sensor sends a signal to the controller and the controller tells the compressor to turn on again.
Not knowing what kind of vehicle you have it is hard to be specific. This is how most A/C systems work. I think you probably need to replace the evaporator as I don’t think the sensor is available. You may want to go to a parts store and ask to take a look at at the replacement evaporator for your vehicle and see if it has a sensor in it. Also it would be a good idea to acquire a Factory Service Manual published by the manufacturer of your vehicle NOT Haynes or Chilton’s. You may be able to find vehicle info at your local library.
Hope this is helpful to you.John[/quote]
Thank you so much, I will take a look at my documentation. I actually have not only the Haynes manual, but also the ford workshop manual in paperback and digital format B) I’ve found haynes is good for general maintenance but anything make/model specific you can’t beat the ford books!
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