Case 210C has A/C problem

[Shimmy1]

Been getting warmer this past week, and noticed that the inside the cab was getting warmer as well. Have had the condenser get full of debris before, so tried that first. Spent 20 minutes blowing everything out, no change. Snapped gauges on, high side appeared to get a little high (around 275 psi), but low side looked ok for the most part (would come down to about 18-20 while compressor was running). Was expecting to see the low side lower, but went ahead and added some juice anyway. Added around 8 oz, low side started running about 25 psi at compressor shut-off, and air was noticeably cooler out of the vents. Now for the strange part. Air gets colder ONLY while compressor is running, warms back up when compressor kicks out. But the most disturbing fact is how the high side acts after I added refrigerant. The compressor kicks in when the low side is at about 45, and the high side is at 180. The low side gradually comes down to about 25, but the high side goes up to about 330-350, then starts dropping, and continues to drop while the compressor is running. Compressor cycle time seems legit, about 20 sec on, 20 sec off. I'm leaning towards there being a restriction somewhere, like a bad dryer, or a malfunctioning expansion valve. Anybody have anything different to suggest?

 

[Junkyard]

I'm leaning towards expansion valve based on how it's acting. Since you've cleaned the condesner that should rule it out. That's the most common restriction I've run into. Might be time to break it open and replace everything. The high side getting to that pressure is usually indicative of a restriction. My .02

 

[Shimmy1]

Might be time to break it open and replace everything.

2100 hrs on the clock. Can't even believe this is even an issue right now.

 

[Junkyard]

I wonder how well they assemble some stuff. We had issues with the linkbelt 210's around the same hours. I agree though it shouldn't be an issue.

 

[Shimmy1]

I wonder how well they assemble some stuff. We had issues with the linkbelt 210's around the same hours. I agree though it shouldn't be an issue.

Interesting. What kind of issues?

 

[Junkyard]

Pretty similar to yours, one had issues on the high side which had me second guessing my gauges. Wouldn't charge like it should and it would cool in weird patterns but I never watched it close enough to see if it had anything to do with the cycle of the compressor. One of them had trash in the expansion valve like they didn't clean the system before they sealed it up and pulled a vacuum. Not sure if I was the first to crack the system or not. The other ended up being a compressor, wouldn't get the high side up like it should be when charged properly. They were both around 2500-2800 hours when we finally broke down and fixed them but they had been acting up the previous summer. I wonder if they aren't run with partially plugged condensers and it works things just hard enough it kills a compressor. My A/C parts guy wasn't fond of the particular compressor brand when I came in for a replacement.....

Same but different lol. I have run into a clutch that slipped. I had pulled my hair out and finally marked the two sides with a paint pen and with a strobe could watch the marks move in relation to where they were when it locked up. Kinda weird on that one.

 

[007]

Hi Shimmy1
It sounds like you have a blockage in your system for sure.
I would not add any more refrigerant as it sounds as if it is all condensed and logged in your condenser at the moment.
There is a gauze filter usually at the TX valve but most blockages occur in the filter dryer.
I have had the desiccant bag burst open in the dryer and block the gauze filter on a number of occasions.
Can you confirm what refrigerant you are running, approx what was the ambient temp of the day when you took those readings and what was the speed setting of your cab fan, and what approx rpm of engine.
Cheers

 

[Shimmy1]

134A, 80°F, I had the fan on both low and high settings, and tried engine rpm anywhere from 1400 to high idle. I ordered an expansion valve and new dryer today.

 

[007]

Hi Shimmy1
I am a little concerned about your original post where you said you would have liked to see your pressures.
Typically to test your system you would open your cab door and run your internal fan at maximum speed and lift your rpm.
This condition will open your tx valve to its full flow and also confirm you are not flashing in your sight glass also in this condition.
on 134a you would be concerned if the pressure went much below 30psi as lower will begin to form ice on your evap.
If you cannot get this pressure up it is sometimes low because of a blocked evap coil or air filter upstream of the evap coil.
Based on your ambient and assuming clean condenser and allowing 10deg TD on the coil i would have expected to see around 125psi condensing pressure.
Condensing Pressures can vary due to air flow but the lower the better.
Just as a by the way automotive hoses are ready to burst when you getting 350 on the high side so i hope you were aware of how stressed the system was when you were testing it and adding refrigerant.
Also very bad for your compressor in that condition as it burns the oil onto the valves with high discharge temps like that.
Hope i helped Cheers.

 

[CatKC]

Been getting warmer this past week, and noticed that the inside the cab was getting warmer as well. Have had the condenser get full of debris before, so tried that first. Spent 20 minutes blowing everything out, no change. Snapped gauges on, high side appeared to get a little high (around 275 psi), but low side looked ok for the most part (would come down to about 18-20 while compressor was running). Was expecting to see the low side lower, but went ahead and added some juice anyway. Added around 8 oz, low side started running about 25 psi at compressor shut-off, and air was noticeably cooler out of the vents. Now for the strange part. Air gets colder ONLY while compressor is running, warms back up when compressor kicks out. But the most disturbing fact is how the high side acts after I added refrigerant. The compressor kicks in when the low side is at about 45, and the high side is at 180. The low side gradually comes down to about 25, but the high side goes up to about 330-350, then starts dropping, and continues to drop while the compressor is running. Compressor cycle time seems legit, about 20 sec on, 20 sec off. I'm leaning towards there being a restriction somewhere, like a bad dryer, or a malfunctioning expansion valve. Anybody have anything different to suggest?

The pressures are going to change with the ambient temperature and should be checked with MAX A/C and MAX BLOWER with ENGINE RPM at around 1500.

If you are checking it at 70 deg F the 'normal' for 134A should be LOW= 35-40 HIGH= 145-160 .
At 80 deg F LOW=40-50 HIGH=175-210
At 100 deg F LOW=50-55 HIGH=315-325

Your statemennt- "The low side gradually comes down to about 25, but the high side goes up to about 330-350, then starts dropping, and continues to drop" is NOT abnormal. What you are seeing is the operation of the expansion valve when the LOW side is too low. That is an indication of a LOW CHARGE, as verified by the low being 25 (assuming the HIGH went down to the 1XX psi range).
You must wait for the readings to 'stabilize' to get an accurate reading.
If it was me I would add 134 -while running and after it stabilized.- (AGAIN- assuming the HIGH is in the 100-200 psi range at 80 deg F.)
Any 'drastic' difference between low-high pressures ONLY AFTER IT HAS STABILIZED would indicate a blockage or bad expansion valve.

Of course if you replace the dryer you will have to charge it and it will work.

 

[007]

Hi CatKC,
Are those pressures for his exact machine or general industry?
Your saying he is condensing 45deg above ambient at 70
but more than 70deg above when ambient 100.
Must have a very small condenser?
Cheers

 

[Birken Vogt]

I am kind of lost on what could be causing this problem but when diagnosing something like this, I like to tape and insulate a thermocouple to the condenser outlet and measure the liquid temperature there. And compare it to the indicated temperature on the high side gauge. If it is a lot lower than the gauge indicates then you know you are slugging all your refrigerant into the condenser. If they are closer to even then probable low charge.

 

[CatKC]

Hi CatKC,
Are those pressures for his exact machine or general industry?
Your saying he is
but more than 70deg above when ambient 100.
Must have a very small condenser?
Cheers

I don't know what you are saying "...condensing 45deg above ambient at 70"
However condenser size is not relevant in pressure readings, as pressure is pressure. . . . .

I will try not to get technical.

Freon that is a -NOT under pressure has BOILING POINT. -
Fahrenheit: R22= -42.1, R12= -21.6, R134(A) = -15.1. This 'represents' the 'capability' of the Freon to 'remove heat'.
The A/C 'GAUGE/PRESSURE reading-is NOT any machine or device/car/truck/excavator specific,- it's only the representation related to the 'OUTPUT temperature which you are trying to achieve' and determines the acceptable readings. (I won't argue about what any particular mfgr SAYS) \
-Refrigerators/freezers have different OUTPUT temperature requirements and will have different normal readings.

Different A/C's for a car/truck/excavator, Etc do have a different -AMOUNT Freon- required for a -full charge- (BASED upon a complete vacuum.)
This 'amount' is determined by the SIZE of the COMPONENTS such as 'condenser', evaporator, hose(s) length, accumulator.

The LOW/HIGH guideline readings registered on a gauge are based upon an STABILIZED operating unit at a specific ambient temperature with an assumed (engine RPM) airflow.

 

[CatKC]

I am kind of lost on what could be causing this problem but when diagnosing something like this, I like to tape and insulate a thermocouple to the condenser outlet and measure the liquid temperature there. And compare it to the indicated temperature on the high side gauge. If it is a lot lower than the gauge indicates then you know you are slugging all your refrigerant into the condenser. If they are closer to even then probable low charge.

An OLD (as I am) check on a car and most outside vehicles (including excavators) , grab (CAREFULLY as it may be HOT) the - INPUT- to the compressor -AFTER- the A/C has stabilized (engine RPM, MAX A/C, MAX blower) . . . . . if it is COOL or COLD you are OK. If it's HOT . . .. . you might want to charge it (BUT ONLY if you suspect a leak. . which is common)
Except for "WORD OF MOUTH" from someone,or passed along, that PAID for a fix......

As with anything, someone wanting to 'make a buck' will tell you -whatever-.
In reality a 'sealed A/C unit will 'rarely' have a problem . . . . EXCEPT the number ONE cause. . LEAKS.

I have worked for many years on A/C units (not as a JOB) and the common -money making- ( I should just say EXCUSE) thing with VEHICLES is a "DRYER" or "RESTRICTION" when it is 'nothing' but a 'low charge'.
House A/C or refrigerator/freezer excuses are a little different.

 

[CatKC]

Hi CatKC,
Are those pressures for his exact machine or general industry?
Your saying he is condensing 45deg above ambient at 70
but more than 70deg above when ambient 100.
Must have a very small condenser?
Cheers

I think you might have misinterpreted my reply.
I believe he was referring to PSI. If not - correct me.
My PSI readings refer HIGH - LOW pressures. Condensing and freezing temperatures of the ambient air or Freon were not addressed.

 

[Birken Vogt]

Hence my suggestion to measure the outlet temperature of the condenser while measuring the pressure.

If you measure your subcooling on the condenser and it is a lot > 15° then you know you are packing it in and it is likely a high side restriction.

If subcool is near zero then you are low on charge.

Subcool is really the only way to measure in a partial charge assuming there are no problems in the system.

 

[CatKC]

I'm leaning towards expansion valve based on how it's acting. Since you've cleaned the condesner that should rule it out. That's the most common restriction I've run into. Might be time to break it open and replace everything. The high side getting to that pressure is usually indicative of a restriction. My .02

KISS- Keep It Simple S. .
The high side -went down- after it ran a while and the system stabilized. The low side was low. UNLESS the high side STAYED high, which it did not . . it is low on Freon.
Have someone replace the evaporator, clean the X, evacuate the system and recharge it. . . . of course it will work. Till next year when it will need more Freon.

It will be difficult to find he leak, usually the compressor seal, as it is in a COLD climate and no one runs the A/C when 'it's cold' to 'lubricate' the seals. (Most A/C's won't run below about 30 deg F, even "Heat Pumps")

 

[CatKC]

I'll try and simplify my previous response.
It's likely low on Freon.
The 'cycle time' is wrong and short (unless the ambient temperature is very low and/or the INSIDE temperature of the unit is very cold) because you are LOW ON FREON.
The reason it cycles so quickly is because there are LOW and HIGH pressure switches in the circuit that control things.
You are cycling too quick because your LOW pressure is saying "if I continue to run it will freeze the evaporator" so I must stop . . cycle.

Whatever you do and decide to replace, once you open the system and 'evacuate and recharge' it will run. . . . . . .till next year.

 

[CatKC]

Hence my suggestion to measure the outlet temperature of the condenser while measuring the pressure.

If you measure your subcooling on the condenser and it is a lot > 15° then you know you are packing it in and it is likely a high side restriction.

If subcool is near zero then you are low on charge.

Subcool is really the only way to measure in a partial charge assuming there are no problems in the system.

- Restrictions - are considerably LESS frequent than LOW charges but are often used by A/C "specialists" to increase the cost of a repair.

I only attempt to provide a simplified -non measuring device- method, if possible. Most excavator 'owners/users' have no A/C tools. They only want it fixed at as low a cost as possible.

 

[007]

Hi Guys
I agree Birken with your condenser sub cooling test but most guys just feel with there hand down the sides of the condenser and you can feel where condensing stops.
I agree with most things you say CatKC.
If you interpret shimmy1 words exactly It can go both ways low on charge or blockage but yes most common symptom is low charge.
If you have a blockage the high side will spike up condense and come back down again.
A spike of 330-350 is high for a system that is not condensing full refrigerant flow but how long did it spike.
So to simplify how can he have high condensing pressure if the compressor has sucked the evap low and is not moving alot of refrigerant (due to lack of charge).
Typically i have found low charge will present low evap pressure and low condensing pressure. (Are his gauges Tip Top?)
He said (The low side gradually comes down to about 25), usually with low charge the comp sucks the evap down to the cut out switch pressure very quickly.
You need experienced eyes looking at the gauges when the comp comes in to gauge what is happening.
A sight glass is invaluable at times like this I assume he has none?
Bear in mind a simple cracked capillary tube on the tx will present like a blockage, so he needs to have a good look around for the obvious.
If he reclaims the charge and measures quantity on new charge will resolve any lack of charge issues.

Regarding High side gauge readings, what you see on your gauge when running is the (temperature/pressure) of the refrigerant when it converts from vapor to liquid inside your condenser.
The size, condition, and efficiency of the condenser coil determine the temperature above ambient the vapor will condense and the pressure you see on your gauge.
So by using your Temp/Pressure chart and knowing your ambient you can figure quickly what sort of pressure to expect on the high side gauges.
In an automotive application where condensers are relatively small and not efficient they can have condensing temp/pressures 90deg above ambient.
Not having seen what he is working on I do not know.
Some pictures would of helped.
The worst high condensing pressures I have seen are those little drop in units above the cabs with condensers in them the size of a shoe box.

cheers