A/C problem is driving me crazy!!!

[jleehoyle567]

For some reason the air in my 03 mounty will not get cold. The passenger side is cooler than the driver but still too hot to leave windows up. i checked the freon level and when the compressor cycles it goes from 70+ psi down to 20 psi. I have added freon but nothing changes. What would cause the drastic pressure changes? Its 95 degrees daily where I live and i have a 1 hour commute in uniform (including ballistic vest). I need A/C ASAP!!!

 

[Elessar65]

Those pressures are WAY on the low side. With your manifold gauges hooked up you should see high side pressure of 220-ish and low side pressure around 60-ish. I don't know the exact specs, but generally if your pressures are that low then you are way low on refrigerant.

As far as drastic pressure changes, thats how an AC system works. The compressor pressurizes R134a vapor to a high pressure, it goes the the condenser in front of the radiator where it is condensed into a liquid. It then flows through an expansion valve or orifice tube which meters the flow into the evaporator in the heater box. When it leaves the expansion valve it goes into a low pressure area in the evaporator where it evaporates back into a vapor, and goes back in to the compressor. This evaporation cools the warm air from the cabin and the blower motor blows it back into the air plenum and through the vents as cool air. More or less anyways, there are a few other parts and stuff in there like all the pressure switches, accumulator, etc...

 

[jleehoyle567]

so basically its safe for the guage to read "dangerous" while the compressor is off? the last thing i need is to blow my system.

 

[joecrna]

Sounds like you are just using the pressure gauge on a freon can. If so that is still OK. When you hook up to the low side, turn the AC on high, fan on high. The compressor really shouldn't shut off and on under those conditions but yes you will see high pressure changes as it does. Your pressure are still really low. You probably still need quite a bit of freon. Depending on ambient temp, the low side on an Ex should be about 40 or a little more. Read the directions on the can carefully and follow them to the letter. Overcharging can be worse than a little undercharged. Also follow the freon manufacturers method when it comes to agitating the can, you don't want liqued in your low side tube.

The real question is, why is your freon level so low. If you need that much you likly have a fair size leak.

 

[Elessar65]

Sounds like you are just using the pressure gauge on a freon can. If so that is still OK. When you hook up to the low side, turn the AC on high, fan on high. The compressor really shouldn't shut off and on under those conditions but yes you will see high pressure changes as it does. Your pressure are still really low. You probably still need quite a bit of freon. Depending on ambient temp, the low side on an Ex should be about 40 or a little more. Read the directions on the can carefully and follow them to the letter. Overcharging can be worse than a little undercharged. Also follow the freon manufacturers method when it comes to agitating the can, you don't want liqued in your low side tube.

The real question is, why is your freon level so low. If you need that much you likly have a fair size leak.

Also, don't hook up the freon can to the high side with it turned on unless you want the can to blow up in your hand. They aren't meant to take that kind of pressure.

 

[blazin8556]

it won't connect anyways. the high side is a bigger port.

 

[jleehoyle567]

looks like im gonna have a pro check it out. i added two cans of r134a to the system and still no luck. no even a little cooler.

assuming there is a blockage in the lines, how would i go about fixing that? or even finding it?

my compressor will kick on for about 5 seconds and then turn back off. during that time the gauge will peak at around 70-75 psi and then drop off to 25 or so. i was told that i could unhook a sensor somewhere that will cause the compressor to run constantly. is this true?

 

[Elessar65]

There are 2 sensors that monitor pressure, a high pressure switch that will kick it off if its too high, and a low pressure switch that will do the same. Not sure of the exact location on your truck, but they are on the ac lines or compressor somewhere. Just be advised that this removes the safety feature of having them, and could trash your compressor, which means that everything should be replaced or bare minimum flushed with special AC system flush product cause any amount of debris in the system will cause it to malfunction.

If you go someplace make sure they evacuate the system and pull a vacuum on it and see if it holds for at least 10 min to check for leaks (should be like 20 or 30 min according to the book, but thats not needed in my experience, 10 min will tell you if there is a leak or not, and time is money) Have them add dye too (most places do anyways, but it never hurts to ask) A lot of places will just charge it and send you on your way without a proper diagnosis.

Edit: You can also just jumper the compressor clutch straight to the battery, but I don't recommend it unless you know what you are doing (See Above). I've done it, but just to see if the clutch is working when diagnosing.

 

[jleehoyle567]

i have the digital climate controls and i havent noticed just a VENT option (but i also havent payed much attention).

is there somewhere that i can find a diagram of the system layout? i dont wanna buy a haynes manual just for A/C.

thanks for all the suggestions so far. im feeling more enlightened.

 

[jleehoyle567]

ok...i bought r134a today and going to attempt to fix my problem. i just want to double check that it is normal operation for the compressor to cycle on and off. i know my crown vic patrol car does the same thing but before i put more pressure in the system i want to make sure.

aslo when it cycles my pressure jumps on the guage. again, is this normal or should it stay steady? i notice when my compressor is running the pressure is much lower than when it off. but i have no way to check high side pressure. (i assume the high side pressure is what it reads when the compressor is off) is this correct

 

[jleehoyle567]

i charged the system tonight and during the time i was putting freon in the low side port i started getting white smoke from my exhaust. i have an open cone filter and my thoughts are that i have a leak near the low side port and the fumes were being sucked into my intake. then i started smelling a strong odor that caused my nose and throat to burn and my eyes to water. thinking i may have a leak i turned the motor off and released all the pressure from the system hoping the smoke and smell would go away. the vehicle eventually quit smoking but the smell is almost unbearable.

it may just be a fluke that it happened at the same time that i charged the system but i am kinda concerned. has this happened to anyone or does anyone have a suggestion/idea of what may be burning?

 

[wildcat40cal]

How is the air volume blowing through the vents? Is there a change when switching to max a/c? My XLS seemed to never blow enough cold air even on max so I searched the forums and found a work around post regarding the recirc door. That door is behind/under the passenger side. Don't know if this is the same problem you're having but it solved my lack of cooling issue. Good luck.

 

[CDW6212R]

Never mind, if you are going to ignore smart advice and logic. I'm not wasting any more of my time on ignorant people.

 

[jleehoyle567]

Never mind, if you are going to ignore smart advice and logic. I'm not wasting any more of my time on ignorant people.

i wasnt aware of any advice you have given. this is the first i have seen of you posting on here.

it appears i have a leak at the low side but i am trying to figure out why the smell and smoking started. no milkshake and no sweet smell so i dont THINK its a head gasket issue. The only other repairs i have made recently on the vehicle was changing plugs.

and CDW, if you feel like you are wasting time then by all means spend it differently. im sure other people will be glad to assist each other.

 

[joecrna]

Yes the compressor will cycle off and on. Very infrequently if AC and fan are both on max and the system is functioning and charged properly.

The pressure on your low side gauge will jump up and down as the compressor cycles. It will read lower when compressor is off and higher when its on.

It will never read high side pressure unless you have a gauge hooked up to the hoigh side port. As said before, they are different sizes. So it is hard to do accidently.

If you have added 2 cans of freon and still don't have at least a partially functioning system something is wrong. I think you probably have a significant leak that will require repair. You either need a bunch of AC equipement or the services of a professional. Cost will likly be comparable but its up to you.

As for the blend door mal###tioning, thats always a possiblity with these trucks. You must however first have a properly charged and functioning AC system before you worry about the blend door.

 

[D Hook]

Never mind, if you are going to ignore smart advice and logic. I'm not wasting any more of my time on ignorant people.

Why all the abhorrance? Looks like you're posting in the wrong forum anyway. I'm pretty sure THIS forum will survive without your advice.