Air Conditioner Refrigerant Charge

[SuiteSuccess]

2006 Volvo D12 using r134a.  Is there a specific chart related to each vehicle (i.e. my Volvo) correlating high side/low side pressures and ambient temperature?  Or is it just a standard chart for any system that uses r134a?  I have available a gauge system so I can check high/low side pressures and static pressure.   My ac is not as cool as it once was and think it may need a charge.

Edited August 23 by SuiteSuccess

[SuiteSuccess]

Got my answer.  Chart applies to any R134a system.  Not vehicle specific.

https://www.acprocold.com/help-and-advice/system-pressure-chart/

 

[Deezl Smoke]

 Please let us know what your gauges do say, and how close to the chart they are.

 The condenser out front can get bug juices and other road spray film on it that you usually can't see, but affects the ability to exchange btu. Blowing with air does nothing. It takes a good soap and water pressure wash. This alone can/will affect the gauge readings when the ambient is warm.

[SuiteSuccess]

7 hours ago, Deezl Smoke said:

 Please let us know what your gauges do say, and how close to the chart they are.

 The condenser out front can get bug juices and other road spray film on it that you usually can't see, but affects the ability to exchange btu. Blowing with air does nothing. It takes a good soap and water pressure wash. This alone can/will affect the gauge readings when the ambient is warm.

Thanks.  Good information.  I took my compressor and air hose over and blew out the condenser but will bring truck home and wash it out with power washer.  I’ll also post the readings.  Interesting, I’ve talked to several auto ac repair shops in case it’s more than a simple charge.  None of them will touch a semi in our area.  Guess it will be dealer or nothing.  BTW, I also used a strong flashlight and traced all the hoses and condenser to see if there were any signs of oil leaks.  Rudimentary but didn’t see any, so hopefully good sign.

[rickeieio]

Carl, keep looking for an independent shop.  Your local Volvo dealer isn't long on honesty.  Nor are they cheap.  Any decent truck repair shop can handle this.  It ain't brain surgery.

Don't use a power washer.  Soak the cooling stack with water, and keep flushing for a bit.  Spray in from behind too, reverse of air flow, especially near the corners.  Once you think you have it pretty clean, spray in some soap.  Most anything will do, I use, Simple Green.  Let it sit for a bit, then flush again, and again.  You'll be amazed at the crud that will come out.

[Deezl Smoke]

 I'd bet, though not much as I'm not much of a gambler, that the system has dye in it already. You can get a proper die light from amazon or maybe even harbor freight and look for visible leaks.

 Look around the compressor clutch and see if the back side of the pulley looks moist and black gritty. That would be a sign that compressor seal is leaking and likely the compressor will fail soon.

 

[Parrformance]

23 hours ago, SuiteSuccess said:

Got my answer.  Chart applies to any R134a system.  Not vehicle specific.

https://www.acprocold.com/help-and-advice/system-pressure-chart/

 

Thank you Suite👍

[SuiteSuccess]

1 hour ago, rickeieio said:

Carl, keep looking for an independent shop.  Your local Volvo dealer isn't long on honesty.  Nor are they cheap.  Any decent truck repair shop can handle this.  It ain't brain surgery.

Don't use a power washer.  Soak the cooling stack with water, and keep flushing for a bit.  Spray in from behind too, reverse of air flow, especially near the corners.  Once you think you have it pretty clean, spray in some soap.  Most anything will do, I use, Simple Green.  Let it sit for a bit, then flush again, and again.  You'll be amazed at the crud that will come out.

Rick,

My pressure washer has a low pressure setting that is just slightly more than a water hose sprayer.  Also I can connect a soap supply to it so I’m gonna give it a washing.  Thanks for the advice.  I did find a local shop and talked to them.  They were same rates as dealer and didn’t give me the warm and fuzzies that AC was in their expertise wheelhouse.  May give J&K in Crossville a call if it comes down to needing a shop.  Hopefully, just needs a good cleaning and a charge.  JW Morgan added a little Freon when he built my bed and have had nothing since.  That’s been 15 years. I can live with a pinhole leak that needs a charge infrequently as long as I’m not losing a lot of oil.

Edited August 20 by SuiteSuccess

[SuiteSuccess]

41 minutes ago, Deezl Smoke said:

 I'd bet, though not much as I'm not much of a gambler, that the system has dye in it already. You can get a proper die light from amazon or maybe even harbor freight and look for visible leaks.

 Look around the compressor clutch and see if the back side of the pulley looks moist and black gritty. That would be a sign that compressor seal is leaking and likely the compressor will fail soon.

 

Ok, more tools and gadgets.  This is getting fun!  😂. Also found a good review on a Freon leak detector for cheap.  May be in the cards also.  I should say I cycled the compressor off and on multiple times to be sure the clutch was engaging and everything seemed to be working properly.

[Darryl&Rita]

I know a local shop. Top notch service. Tragically, they're local to us, not you.

Second vote for a Simple Green stack soak. Cleans any petroleum product, but isn't too aggressive. Lots of our farm equipment gets a fall clean, starting with the leaf blower. You want volume, not pressure. If there's been any leakage anywhere near the stack, Simple Green is the next step. Mixed in a plant sprayer, soak it down. Running all over soak. Let it sit for as long as you remember it's on there. Garden hose time, straight hose, no nozzle. Again volume, not pressure. Depending on the equipment, we'll pull the stack apart to clean better, faster. Doesn't usually make it any faster, but it's definitely cleaner.

[Deezl Smoke]

This was our farm Prostar radiator. We had to remove the hood, and carefully disassemble the stack to get to it. Tried blowing down between the radiator and I think the next up front was the ataac with no luck. Taking it apart was the only way. Got the pressure washer into the shop to back flush it. Learned it isn't always the junk coming in through the grill, but stuff can be sucked up from beneath while the grill is clean.

[SuiteSuccess]

27 minutes ago, Darryl&Rita said:

I know a local shop. Top notch service. Tragically, they're local to us, not you.

Second vote for a Simple Green stack soak. Cleans any petroleum product, but isn't too aggressive. Lots of our farm equipment gets a fall clean, starting with the leaf blower. You want volume, not pressure. If there's been any leakage anywhere near the stack, Simple Green is the next step. Mixed in a plant sprayer, soak it down. Running all over soak. Let it sit for as long as you remember it's on there. Garden hose time, straight hose, no nozzle. Again volume, not pressure. Depending on the equipment, we'll pull the stack apart to clean better, faster. Doesn't usually make it any faster, but it's definitely cleaner.

Ok. You smart people convinced me 😊.  Thanks for the suggestions. 

[lappir]

I've had to recharge my HVAC units almost ever year. Have the tech do an evacuation, see how long it holds a vacuum and if it's over 8 hours, then just have it recharged with the appropriate amount. You can spend thousands in looking for a leak that can never be found, or hundreds on recharging as needed. 

 

 

Rod

 

 

Fod

[rickeieio]

Our Volvo had a pinhole leak in the line behind the engine air filter.  Then the next year, it needed the lines going to the sleeper compartment.  Check those areas for signs of oil.

[SuiteSuccess]

Okay hooked gauges up and said I would post some readings for critique.  Ambient temperature 70.  Static (engine cold, not running):  68 psi high and low.  Engine running and warmed up Low side 28; High side 130.  Chart at 70* should have been Low 35-40; High 145-160.  So I was low/low indicating needing some coolant.  Vent temps were 69 before any additions.  Added 12 oz of coolant in 4 increments separated by 10 minute intervals.  Ambient temperature was now 75*. Low side was 32 (chart 35-45); High side 160 (Chart 150-170).  Vent temp 58*.  Did notice that engine fan kicked on frequently and both low and high sides decreased pretty significantly but recovered quickly to above readings when fan was off.  Seemed also compressor was short cycling a bit but may have been my imagination.  Anyway going back to truck tomorrow and will recheck all pressures and may need a bit more refrigerant.  Also changed out cab air filter for good measure.  Any comments, criticisms, suggestions?  
p.s. Haven’t charged an ac in decades back when you didn’t gauge just grabbed a can of Freon and pumped the whole can in on the low side.

[Deezl Smoke]

 I remember those R12 days. Lots of procedures best not told here on the www went on back then.🤭

 IMO, you couldn't ask for better temps to charge the system in.

 Some equipment will disengage the compressor when the prime mover fan kicks on, some don't.

 If the compressor does start to "short cycle" I believe that is a sign of the expansion valve having issues. I wouldn't be afraid to run on the high side of those recommendation numbers.

[SuiteSuccess]

53 minutes ago, Deezl Smoke said:

 I remember those R12 days. Lots of procedures best not told here on the www went on back then.🤭

 IMO, you couldn't ask for better temps to charge the system in.

 Some equipment will disengage the compressor when the prime mover fan kicks on, some don't.

 If the compressor does start to "short cycle" I believe that is a sign of the expansion valve having issues. I wouldn't be afraid to run on the high side of those recommendation numbers.

Unfortunately was working at the storage facility.  Didn’t have a fan with me to blow on the condenser to keep it cool so think that is why truck fan came on so often IMO.  Will carry a couple with me tomorrow and give an update.

[lappir]

In my opinion having the truck fan turn on is best, but if it's cycling too often it's not good. My mechanic recommended the computer being set to at least two minutes of run time any time the fan was needed, but this was on my old truck. So far after an evac and recharge of the new to me truck I've had COLD A/C every time I need it. 

If there isn't air running across the evaporator (or condenser) it's harder to exchange the heat with the ambient air, that's why the a/c is colder running down the road at highway speed than it is at slow speeds in town when you really need it to be cooler. Hence the fan cycles. 

 

Rod

[ddm502001]

As rebuilt my KW replaced Condenser, all flexible hoses, Receiver Drier, Compressor and clutch and Both Evaporator coils(Cab/Bunk) due to corrosion or damage.  Was obvious as got the truck running and all systems functional had a bad HP Fan Engage switch on the HP Line to the Condenser was a easy fix where that powers the air clutch solenoid to engage besides the engine temp switch I had also replaced while rebuilding the engine.  Some engines use a Viscous Temperature Engaged fan hub, no air lines with a finned aluminum hub, these do not generally age well and do require replacing in a periodicity.  Should the fan not engage at slow speeds or considered High Heat loads the systems are designed to purge rather than explode.  Should be a pop off valve on the Compressors used on these and that will produce a loss of refrigerant in those conditions.

[Parrformance]

9 hours ago, lappir said:

In my opinion having the truck fan turn on is best, but if it's cycling too often it's not good. My mechanic recommended the computer being set to at least two minutes of run time any time the fan was needed, but this was on my old truck. So far after an evac and recharge of the new to me truck I've had COLD A/C every time I need it. 

If there isn't air running across the evaporator (or condenser) it's harder to exchange the heat with the ambient air, that's why the a/c is colder running down the road at highway speed than it is at slow speeds in town when you really need it to be cooler. Hence the fan cycles. 

 

Rod

I added a switch in the dash that engages the fan whenever pressed.

Great for stuck in traffic or keeping the dogs cool anytime we are idling for a while.

[SuiteSuccess]

My truck has an air clutch on the fan.  Had that replaced several years ago.  So back to truck today.  Rechecked all my pressures, was on low side of normal for ambient temp of 75* so added a little more refrigerant.  BTW took a fan over to blow across condenser coil so truck fan only kicked in once at the end.  For the final numbers:  Static engine of 72.  Running (ac on) High side 165/low 42.  Normals based on outside temp High 160-170/low 35-45.  My final numbers were after running for 15 mins.  Vent air temp was 56*, but think it will be lower like Rod says when truck is in motion.  I’m satisfied for now.

Edited August 24 by SuiteSuccess

[rickeieio]

3 hours ago, SuiteSuccess said:

 I’m satisfied for now.

But, you're not the one who needs to be satisfied.🤣

[Deezl Smoke]

20 hours ago, SuiteSuccess said:

My truck has an air clutch on the fan.  Had that replaced several years ago.  So back to truck today.  Rechecked all my pressures, was on low side of normal for ambient temp of 75* so added a little more refrigerant.  BTW took a fan over to blow across condenser coil so truck fan only kicked in once at the end.  For the final numbers:  Static engine of 72.  Running (ac on) High side 165/low 42.  Normals based on outside temp High 160-170/low 35-45.  My final numbers were after running for 15 mins.  Vent air temp was 56*, but think it will be lower like Rod says when truck is in motion.  I’m satisfied for now.

 Yep, it's all about btu exchange. More lower temp air passing through the condenser pulls more heat away with it. Glad it's working, and without a huge parts repair bill.