Diagnosing air conditioning compressor issue

[edcantu9]

Diagnosing air conditioning compressor issue
I posted yesterday, but I was not educated on how to use the gauge properly.

After running the car for 5 minutes, The pressure on the low side fluctuates 40 to 80 psi. And it just keeps doing it. Goes down to 40 goes up to 80 etc. this correlates with the compressor clutch activating.

On the high side, the PSI goes from 100 to 110 PSI. And it fluctuates up and down and correlates as well with the low pressure going up and down, and the clutch activation.

I understand if I can't get an answer, but I am mechanically inclined I like working on cars. This is my first air conditioning issue ever. I want to find the right way to diagnose it.

One thing I would like to know is if my car overcharged, under charged, this is my compressor working properly? If anybody knows any resources that are really direct and to the point with learning please point me to them.

The reason I am looking into this is because now it is summer the vents are not blowing out cold air.

 

[Kaizen]

Your compressor sounds like it’s working right. It compresses on the low side which drops that number while increasing on the high side. Google what your car should show for a high number. That might be a little low indicating you need freon.
If it’s in line and you are getting hot air it’s probably a blower door under the dash or some other internal control.


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[edcantu9]

Your compressor sounds like it’s working right. It compresses on the low side which drops that number while increasing on the high side. Google what your car should show for a high number. That might be a little low indicating you need freon.
If it’s in line and you are getting hot air it’s probably a blower door under the dash or some other internal control.


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It is for a 2003 Ford Escape v6.

 

[kapnkirk]

Sure sounds as on the low freon side. Add the appropriate freon (probably 134) not too many use 12 any more, and make sure to bleed the hoses and add the freon thru the low side.

You can find some good video's on youtube to bleed the hoses and add freon, if necessary you can jump the low pressure switch to make adding freon faster and easier. Then just put a gauge in one of the vents inside the car and add freon until you can get around 30-35 degrees under ambient.

 

[edcantu9]

Sure sounds as on the low freon side. Add the appropriate freon (probably 134) not too many use 12 any more, and make sure to bleed the hoses and add the freon thru the low side.

You can find some good video's on youtube to bleed the hoses and add freon, if necessary you can jump the low pressure switch to make adding freon faster and easier. Then just put a gauge in one of the vents inside the car and add freon until you can get around 30-35 degrees under ambient.

That sure sounds like it to me too. I'm just worried that I don't want to put too much and break it.

I've learned that diagnosis is key. that way you don't mess something up or waste money for no reason. I just want to find something that says if this is happening this is the problem. And I can't seem to find anything that relates to my specific issue with the symptoms.

 

[38Chevy454]

Normal high side pressure for R-134a is around 250-350 psi on a hot day. Are you sure you are sensing the correct pressure on high side? Your compressor kicking on and off is to be expected, but is it doing at a rapid pace? Called short cycling, and that is usually caused by low on refrigerant. If your high side is only going from 100 to 110 psi, in the same short period your compressor kicks on, it all sounds like you are low on refrigerant.

 

[edcantu9]

Normal high side pressure for R-134a is around 250-350 psi on a hot day. Are you sure you are sensing the correct pressure on high side? Your compressor kicking on and off is to be expected, but is it doing at a rapid pace? Called short cycling, and that is usually caused by low on refrigerant. If your high side is only going from 100 to 110 psi, in the same short period your compressor kicks on, it all sounds like you are low on refrigerant.

Yes I am 100% sure on the high side pressure. That is nowhere near 250 to 350 range. It is doing it at a rapid pace. I would say 20 seconds between each shut off and turn on.

my concern is that I do not know how much refrigerant is in there. I know it's sensitive how much should be in there. What I've gathered so far is that I should keep adding refrigerant until it stops short cycling?

 

[Kaizen]

That sure sounds like it to me too. I'm just worried that I don't want to put too much and break it.

I've learned that diagnosis is key. that way you don't mess something up or waste money for no reason. I just want to find something that says if this is happening this is the problem. And I can't seem to find anything that relates to my specific issue with the symptoms.

Use a kitchen scale. Put the new can on it and zero the scale. As the ounces go in you will see negative numbers. Just put six ounces in and let it run watching the gauges and the thermometer you should have in the vent in dash. Get a can with uv dye in it so if you have this bro lemme again you can use a uv flashlight and see where it’s leaking


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[edcantu9]

Use a kitchen scale. Put the new can on it and zero the scale. As the ounces go in you will see negative numbers. Just put six ounces in and let it run watching the gauges and the thermometer you should have in the vent in dash. Get a can with uv dye in it so if you have this bro lemme again you can use a uv flashlight and see where it’s leaking



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Thank you that is good advice!

 

[edcantu9]

Use a kitchen scale. Put the new can on it and zero the scale. As the ounces go in you will see negative numbers. Just put six ounces in and let it run watching the gauges and the thermometer you should have in the vent in dash. Get a can with uv dye in it so if you have this bro lemme again you can use a uv flashlight and see where it’s leaking


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What would start happening if I put in too much? How would I know?

 

[jsaw]

Only way to know for sure how much is in the system is to use a recovery machine that is capable of weighing the refrigerant that is pulled out of the system.

If you just add refrigerant to a partially filled system, you are kind of guessing on the amount in the system.

Im not saying that you cant slowly add some refrigerant while watching the outlet temperature. If it is charged enough, it will get down to around 40 degrees or so. I like to add a shot of leak trace dye to make it easier to find a leak down the road.

 

[kbeefy]

Or.... You could pay $100-150 to someone with a machine capable of recovering your refrigerant, evacuating and leak checking it like should be done.

 

[rayra]

Your pressures are supposed to fluctuate / shift like that when the compressor activates. And it means your power, relays, and compressor are all working.

The values seem a little low. Depends on your vehicle's specs, which you need to find out before shoving more refrigerant in.

You should also find out what your 'at rest' pressure ought to be. And you can tell that by connecting a gauge after the system has been at rest for some time, engine off. And measure with engine off. The orifice tube is what forms the division between low and high side and once at rest the pressure equalizes throughout the system. If you have a current leak, a slow leak, that at rest pressure measurement will tell the tale. Before you spend money putting more refrigerant in.

Question is if your loss of cooling was sudden or over a protracted time of non use, in which case it might be just a case of dried seals / o-rings.
Since you appear to be a bit on the low side, you could possible deal with everything by adding a combo can of sealer, leak dye and refrigerant. That may solve a slight leak, show you were the leak was, and bring your cooling temps down. An das you continue to use the vehicle, it may solve your problem or at least give you a better indication of where the problem lay.

I just went thru such an evolution on my '02 Suburban. $15 for such a combo can, $7 for a UV flashlight, some runtime and exploration at dusk, I found the main high-side hose had a crack. I also found a little sign of leakage in the dashboard evaporator and dye sign at the condensate drain.
I was losing system pressure and ran it until it was nonfunctional again (not enough pressure for the compressor to activate) and breached the system to replace the hose.

I spent about $225 for the hose, proper gauge / fill set and a cheap vacuum pump, and the 48oz of R134a my vehicle called for. It's working pretty darn good. And at a total cost less than my local AC shops would charge for a 'diagnostic'.

 

[jimindm]

With out a reclaiming machine you will never know how accurate you are for charging. Unless You vent it all and start from nothing in the system.

Not that I would do that, and if you did vent it, you would want to vacuum the system down.

Likely a few tools you do not have, but it does sound like you have an actual gauge set.

I would guess you are low on freon. How much is anybodies guess. Some one that works with freon a lot could get it close. 134A is less forgiving than the old stuff. You need to be pretty close or it effects cooling.

So somethings to do. Make sure your cooling fan is running. Most likely it is controlled by the PCM. It may not run until you get enough charge into the system. With pressures of 11 on the high side, very likely not high enough to trigger constant fan operation.

Being in central Iowa I can tell you the humidity is high and it should be draining a ton of water off of the evaporator. When working correct. Usually you can feel the hoses or tubes after the orfice system. Unfortunately I think escapes have an expansion valve located right at the firewall, so this will be tough.

Hook you gauges up and just burp the low side, adding freon. Small amounts. Every time you add some, the compressor should run a little longer before in cycles. Once the compressor is on more than off, add even smaller amounts.

Doing this at an idle you should be OK if you sort of creep up to getting about full. Once compressor is running more and more, or constant, the cooling fan should be running also.

Once you get the compressor staying on, run the idle up to about 2000 rpm. See if compressor starts cycling again. If it does just add small doses of freon, until the compressor run mostly. You are getting close.

I never tell one to try to get to a certain pressure on either side of the system. There is just to much that effects the pressures.

Low side you will want it to be in the mid 40s , and high side 200-250.

You should be able to get it close enough that it cools OK. Doing it this way.

AC work is hard to do. You really are trying to diagnose something by taking two screen shot of the system, on opposite ends. The basics are the same for every system. You can read up on them, to know the system a little better.

 

[jimindm]

From a guy that does it for living never put a can of sealer stop leak in it. The dye is great and I would recommend it.

To many reclaim machines have been messed up by the stop leak. Most shops will run from it, if you put it in. Most have identifiers now, that are not cheap, but it saves problems with an AC machine that gets stop leak ran through it.

Just not a good thing.

 

[rayra]

it's a vicious circle. AC business has expensive gear and high overhead, charges high fees, DIY folks find a way to solve it themselves, because the shop wants more than they can afford.

Heck I was digging around youtube for shortcuts to excise my evaporator in case I decided it needed to be replaced, because no way in hell was I spending 1/3 of what I paid for the vehicle to pay mechanics' rates for all the labor to remove my steering and dash and ductwork to get to the evap. And I found some methods that were reasonable.

Tire shop guys complain about Slime in flats, too. Sometimes it's necessary and if it can't get the job done that's part of what my AAA+ membership is for, because the tow guys charge way too much, too.

The line of folks wanting to tap my wallet is very long. Got to economize wherever I can and frankly your recovery machine is a business expense / tax writeoff.

 

[edcantu9]

it's a vicious circle. AC business has expensive gear and high overhead, charges high fees, DIY folks find a way to solve it themselves, because the shop wants more than they can afford.

Heck I was digging around youtube for shortcuts to excise my evaporator in case I decided it needed to be replaced, because no way in hell was I spending 1/3 of what I paid for the vehicle to pay mechanics' rates for all the labor to remove my steering and dash and ductwork to get to the evap. And I found some methods that were reasonable.

Tire shop guys complain about Slime in flats, too. Sometimes it's necessary and if it can't get the job done that's part of what my AAA+ membership is for, because the tow guys charge way too much, too.

The line of folks wanting to tap my wallet is very long. Got to economize wherever I can and frankly your recovery machine is a business expense / tax writeoff.

Yes I agree, everything is expensive! You have to learn to do things yourself! The key is to doing it the right way!

 

[edcantu9]

Or.... You could pay $100-150 to someone with a machine capable of recovering your refrigerant, evacuating and leak checking it like should be done.

No way! This is garage journal, this is why we have garages and thousands of dollars worth of tools!

 

[edcantu9]

With out a reclaiming machine you will never know how accurate you are for charging. Unless You vent it all and start from nothing in the system.

Not that I would do that, and if you did vent it, you would want to vacuum the system down.

Likely a few tools you do not have, but it does sound like you have an actual gauge set.

I would guess you are low on freon. How much is anybodies guess. Some one that works with freon a lot could get it close. 134A is less forgiving than the old stuff. You need to be pretty close or it effects cooling.

So somethings to do. Make sure your cooling fan is running. Most likely it is controlled by the PCM. It may not run until you get enough charge into the system. With pressures of 11 on the high side, very likely not high enough to trigger constant fan operation.

Being in central Iowa I can tell you the humidity is high and it should be draining a ton of water off of the evaporator. When working correct. Usually you can feel the hoses or tubes after the orfice system. Unfortunately I think escapes have an expansion valve located right at the firewall, so this will be tough.

Hook you gauges up and just burp the low side, adding freon. Small amounts. Every time you add some, the compressor should run a little longer before in cycles. Once the compressor is on more than off, add even smaller amounts.

Doing this at an idle you should be OK if you sort of creep up to getting about full. Once compressor is running more and more, or constant, the cooling fan should be running also.

Once you get the compressor staying on, run the idle up to about 2000 rpm. See if compressor starts cycling again. If it does just add small doses of freon, until the compressor run mostly. You are getting close.

I never tell one to try to get to a certain pressure on either side of the system. There is just to much that effects the pressures.

Low side you will want it to be in the mid 40s , and high side 200-250.

You should be able to get it close enough that it cools OK. Doing it this way.

AC work is hard to do. You really are trying to diagnose something by taking two screen shot of the system, on opposite ends. The basics are the same for every system. You can read up on them, to know the system a little better.

Thank you for taking the time to write this out. This really gave me a good insight of what I need to do!

 

[Kaizen]

What would start happening if I put in too much? How would I know?

It would stop working. Too much acts like not enough. The compressor won’t kick on. Like I said put six ounces in and see if it’s cool enough. If it is then stop. If not add another 3 until you get it blowing cold.


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[firebirdparts]

Diagnosing air conditioning compressor issue
I posted yesterday, but I was not educated on how to use the gauge properly.

After running the car for 5 minutes, The pressure on the low side fluctuates 40 to 80 psi. And it just keeps doing it. Goes down to 40 goes up to 80 etc. this correlates with the compressor clutch activating.

On the high side, the PSI goes from 100 to 110 PSI. And it fluctuates up and down and correlates as well with the low pressure going up and down, and the clutch activation.

I understand if I can't get an answer, but I am mechanically inclined I like working on cars. This is my first air conditioning issue ever. I want to find the right way to diagnose it.

One thing I would like to know is if my car overcharged, under charged, this is my compressor working properly? If anybody knows any resources that are really direct and to the point with learning please point me to them.

The reason I am looking into this is because now it is summer the vents are not blowing out cold air.

Undercharged. Everything is working fine otherwise.

 

[redmondjp]

Here's a tip that I got from an old-timer HVAC technician: hold your hand on the suction line at or near the compressor (sometimes not possible on a car) - slowly add freon to the system, until you feel the line getting cold at the compressor. Then you have enough refrigerant in the system.

I have both an R12 and a R134a refrigerant machine and have been working on car AC for 35 years now. I've used this trick myself several times and it has not steered my wrong, when I haven't had the A/C machine available and just needed to top off a system from a can.

 

[edcantu9]

!I wanted to thank everyone! This site is the best. I can feel like a complete dummy, next thing you know I fix it!

I watched some videos on how to administer the r134a, with my gauges, sure enough the high side started to come up and I had a thermostat on the vent. It went from 100degrees to a nice 48 deg after 2 cans!!

Now time will tell if I have a leak.

Thank you all again!!! Seriously from completely dummy of this subject to feeling some confidence in 24 hours.

 

[texasprd]

The OP should look up a R134a pressure/temperature chart, and see how his readings correlated with ambient air temperature.

 

[Kaizen]

!I wanted to thank everyone! This site is the best. I can feel like a complete dummy, next thing you know I fix it!

I watched some videos on how to administer the r134a, with my gauges, sure enough the high side started to come up and I had a thermostat on the vent. It went from 100degrees to a nice 48 deg after 2 cans!!

Now time will tell if I have a leak.

Thank you all again!!! Seriously from completely dummy of this subject to feeling some confidence in 24 hours.

All it takes is determination, some tools, and some research and you can accomplish amazing things. Won’t always work out the first time or be as good as a pro but the skill set will get there. Good job


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