Automotive Air Conditioning Information Forum

Good evening all,
I hope noone takes objection to me posting on here about an earthmoving machine...
Long time lurker on the forums here, finally registered an account hopefully to have someone point out something I have missed on this machine.
I am an auto electrician with 10+ years experience, VASA member and RTA account holder down under and have a Hyundai Excavator thats causing me to tear my hair out at the moment.

The machine is a R145-CR9, I originally did a service call to the machine in December and found that the Compressor was just begining to sieze, it didnt lock up had tight spots when rotating the Compressor by hand. Drained the oil and couldnt see any evidence of a internal failure no metal swarf etc. So I supplied and fitted a new Compressor, TXV, and drier. I flushed the lines and reverse flushed the heat exchangers, left them in the sun for better part of two days and ran high pressure nitrogen through them to ensure I had no flush left over all seemed ok.

I purged the air from the lines when everything was reassembled, changed over to tracer gas with hyrdogen and went all over no leaks detected. Applied big blue to all the unions etc all ok no indicated problems.

The Compressor is a Delphi v5, 24v single A section and has a Red Control valve (according to my book thats a 44psi set point.) I couldn't obtain the OE data for charge weight so I charged to a known spec I did on an indentical machine 12 months ago, 800g R134a, and monitored the pressures and subcooling as I weighed it in and everything seemed ok.
Admittedly it was not an ideal day to be doing the work as the day was a cool day and I was worried about the potential of overcharging it so I took a bunch of measurements on a performance sheet as follows, after running the machine for 20 mins. Sorry for you guys in the US for the metric measurements.
Ambient - 21c
RH - 77%
DP - 17c
Discharge Pressure - 850kpa
Converted to Temp - 38c
Condensor Inlet - 38c
Reciever Outlet - 28c
Suction Pressure - 200kpa
Water draining off - Yes
Vent Temp range - 5c-7c
Cycle time - Around 23 on 40 off.

Everything appeared OK and as normal. No complaints from the machine operator and I didnt hear back from them to say there was a problem.
Fast forward to last week.
Complaint was that it wasnt cooling after about half an hour of machine run time. I went out again, visually checked over the system nothing untoward apart from a loose drive belt. I grabbed the pulley and could turn the compressor by hand so it hadnt seized and had no tight spots. I tensioned the belt up and checked over, all appeared ok. I didnt take a performance test this time as I didnt believe there was anything wrong with it. I wound the engine speed up high to simulate the machine in work and no problems.
Chased up a replacement belt and fitted, run the machine for half hour, nipped the belt up again, tested, all working as far as I could tell.

Two days later I got a call to say that it had thrown a belt again. I attended, checked over the machine once again and couldnt see anything obviously wrong. Went to great effort to get a small ruler down in the guts of the machine to check if the pulley was somehow misaligned but it was spot on.

I grabbed the front of the compressor and once again can turn it freely by hand and no problem there. I removed the tensioner from the engine so I could sus out the condition of the idler bearing, no problems there, and no evidence of it being hot either.
Supplied and fitted another belt. Ran the machine at high speed, took another performance test. Readings as follows,
Ambient - 25c
RH - 95%
DP - 25c
Discharge Pressure - 1250kpa
Converted to Temp - 51c
Condensor Inlet - 52c
Reciever outlet - 38c
Suction Pressure - 200kpa
Water draining off - Yes
Vent Temp Range - 6-8c
Cycle time - Around 20 on 25 off.

I had a call today to tell me that the machine had run for about an hour today, before belt noises started and it eventually shredded another belt.

The only thing that doesn't quite resonate qith me is the suction pressure of 200kpa. I have never quite been able to get my head around the concept of the manual style control valve. If this compressor has a Red Delphi control valve with a setting of 44psi, that roughly comes to 300-ish kpa which I am significantly less than that and I have never seen a system cool properly at 300kpa.

Any opinions or feedback on anything that looks wrong from the other members here would be appreciated. I am out of ideas at the present moment. I really dont think that this is an alignment issue not considering it was fine for a month nearly two months before the problem began occuring.

I look forward to hearing from you all.
Regards,
OP.

partial checklist:
1) In USA heavy trucks with Vee belt use Dayco 17/32 top width belt
2) never use back side tension pulley w/ single Vee belt
3) Severe start up at higher rpm liquid slugging can cause belt failure
4) long belt spans w/o idler pulley allow excessive belt bounce
5) Tension pulley should be on slack side of belt
hotrodac

You got lucky...Ice is one of the many sharp shooters here....he is on the SAE and for starters has advised and worked on military equipment...
good luck

I see nothing wrong with any of your data, I have no idea what a "red" v5 valve should control to, but your suction pressures look perfect to me. Hard to know about the charge unless you run it at higher loads.

I'm an AC engineer and we generally do everything in absolute pressures, I'm converting like mad whenever chatting on this board since gauge sets are in gage pressure. 44 psia = 29.3 psig = 202 kpag My guess is that the Delphi nerds spec the valve in psia?

This is a rather lengthy and detailed post. So to make for easier reading and diagnosing for those of us in the USA, I converted Grams, Kilopascals, and Celsius to Ounces (net weight), PSIG (gauge pressure), and Fahrenheit, highlighting all of the latter in this color.

DSAE.Casino wrote: ↑Thu Feb 02, 2023 2:31 am Good evening all,
...
The Compressor is a Delphi v5, 24v single A section and has a Red Control valve (according to my book thats a 44psi set point.) I couldn't obtain the OE data for charge weight so I charged to a known spec I did on an indentical machine 12 months ago, 800g (28.2 ounces net weight) R134a, and monitored the pressures and subcooling as I weighed it in and everything seemed ok.
...
Admittedly it was not an ideal day to be doing the work as the day was a cool day and I was worried about the potential of overcharging it so I took a bunch of measurements on a performance sheet as follows, after running the machine for 20 mins. Sorry for you guys in the US for the metric measurements.
Ambient - 21c (70°F)
RH - 77%
DP - 17c (63°F)
Discharge Pressure - 850kpa (123 PSIG)
Converted to Temp - 38c (100°F)
Condensor Inlet - 38c (100°F)
Reciever Outlet - 28c (82°F)
Suction Pressure - 200kpa (29 PSIG)
Water draining off - Yes
Vent Temp range - 5c-7c (41-45°F)
Cycle time - Around 23 on 40 off.
...
Supplied and fitted another belt. Ran the machine at high speed, took another performance test. Readings as follows,
Ambient - 25c (77°F)
RH - 95%
DP - 25c (77°F)
Discharge Pressure - 1250kpa (181 PSIG)
Converted to Temp - 51c (124°F)
Condensor Inlet - 52c (126°F)
Reciever outlet - 38c (100°F)
Suction Pressure - 200kpa (29 PSIG)
Water draining off - Yes
Vent Temp Range - 6-8c (43-46°F)
Cycle time - Around 20 on 25 off.
...
The only thing that doesn't quite resonate qith me is the suction pressure of 200kpa (29 PSIG). I have never quite been able to get my head around the concept of the manual style control valve. If this compressor has a Red Delphi control valve with a setting of 44psi, that roughly comes to 300-ish kpa (~44 PSIG) which I am significantly less than that and I have never seen a system cool properly at 300kpa (44 PSIG).
Any opinions or feedback on anything that looks wrong from the other members here would be appreciated. I am out of ideas at the present moment. I really dont think that this is an alignment issue not considering it was fine for a month nearly two months before the problem began occuring.
I look forward to hearing from you all.
...

More sharpshooters.....

Good evening all,
Thanks for the quick replies. I've had more info on the fault straight from the machine operator that i'll discuss but ill reply to everyone first...

Ice-in-tropics - A good point about the industrial belts being 17/32 of an inch. All the belts used thus far have been 13A section. I managed to get my hands on a belt the same length as the 13A1140 I have been using in an industrial belt with that 17/32 section. Ill fit that up when I go out tommorrow and see how it goes. The tensioner is on the slack side and it runs on the V (ie not on the back) so I dont see a problem there. Its only a very short belt run so I doubt normal oscillation is throwing it, and lastly an interesting point about liquid slugging. I knew this could be a problem but have never actually seen it happen myself so I didn't give it a second thought. It got me thinking though...more on that in a minute.

Tbirdtbird - Yes many sharpshooters on here hence why I figured that this would be as good of a place as any to bounce the ideas and see if anyone could see something I had obviously missed.

DetroitAC - Thank you for oncing over the numbers. I agree that there isnt anything wrong with the suction side pressure, however I ended up getting confused when the spare parts supplier suggested that the 'red' control valve in my compressor had a 44psi set point (303kpa) which just simply didn't make sense. You are right about the Control valve spec being in PSIA, as that 44psi converted to gauge gives 202kpa as you pointed out. I confirmed this by looking in the same parts book for a 'blue' control valve like what is fitted to our VT Commodores over here, and its listed as a 41psi valve. Convert this to a gauge pressure and get 181kpa which matches every Commodore AC I have ever serviced in the last 10 something years so thats a winner.

JohnHere - Sorry about that. In future I will do the conversions as I am writing and note both. Thanks for going to the effort to make it easier for you guys stateside.

Okay now onto the interesting bit...
I spoke with the machine operator at length late this week trying to twist as many details out of him as I could about what he was doing was the machine slewing at the time did you have the bucket loaded etc, after a length of time pulling teeth he got snippy and said something like,
"Look mate all I did was turn the fan speed down"
So I am heading out to look at the machine tomorrow and I will be putting a belt on, running at high speed high load door open as normal when I performance test, then dialing the fan speed back and shutting the cab and monitoring my pressures. I am thinking that the Compressor may not be destroking, and if it is still running at high displacement the TXV should theoetically shut down, and my high side should rise. If that happens I will have my thermometer attached at the two evaporator lines monitoring if I still have a full evaporator, and if I still have the same temprature on the other side of the TXV it stands to reason that there could be liquid in there making its way to the compressor. I just would have thought given the length of the lines that any liquid would flash on the 6m+ uphill hose run before it got there. Anyway, we will wait and see what happens tomorrow.

Thanks for all the help guys and I will update when I know more.
Regards,
OP.

How much oil, which type, and what viscosity did you install, and where and how did you add it? I don't have the specs for this machine, either, but it seems to me that around 8 ounces in total (236.6 milliliters) would be about right.

Seems like only a belt mechanical issue to me. Is the compressor mounting to something solid or to brackets that might be bent? Straight edge laid on crankshaft pointing to compressor and tensioner and then straight edge on compressor pulley pointing to crankshaft and tensioner. Maybe the tensioner is bent? and the belt is walking itself off, or bad tensioner bearing?

Good Morning all,
JohnHere - it was a brand new Compressor fitted and system was flushed through. I drained the oil that came with the Compressor and added it straight back into the sump, 220mL I cannot remember the grade exactly it was printed on a sticker on the side of the Compressor.

DetroitAC - I went out to the job site on Sunday and fitted up this new belt, tensioned, got a small 15cm ruler in there and checked squareness and alignment and all looked fine. I took the tensioner off the block completely and checked for straightness and it all looks good. Also while it was out I checked the bearing in the idler and looks and feels fine. I was pretty confident I had it sorted ran the machine at high idle for approx 1hr and noticed a bit of belt noise on clutch cycle - crawled up under there and checked it sure enough it had come a little loose nipped it up and continued to run the machine for another 3 hrs and no problems noted. Machine operator rung me at about 1pm yesterday to tell me it had just snapped the belt but had been working fine all morning prior to that. I asked him to try and spin the tensioner and Compressor by hand and he said that they were fine. I am at the point im about to admit defeat on this one. All my pressure and temprature readings looked fine, performance was excelent. Only thing I can think at this point is an intermittant pump issue. Ill keep you posted.

Regards,
OP.