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AC pressure readings and problem with dealer.

Doug580l

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Apr 15, 2018
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301
Location
Southern Illinois
I read through this thread last night and had to let it stew a bit on the burning inside my head. I do have a couple of questions and observations based on what little I've had to do for operator complaints about air conditioning. I'll play the levels advocate here for a minute or two.

My first question is do you shut the door and all the windows while running the AC? Do you have it recirculating the air inside the cab. The reason I bring it up is because you keep getting water being blown out the vents. Water would be a normal occurrence in a humid and hot climate because cooling the air would drop the water out. Cool air won't hold as much water. But if you are recirculating the air in the cab, the air will get dryer over time and the water will go away. We had tremendous complaints about AC when the weather would warm up in this area. The reason would be obvious when we drove out and saw the machine from half a mile away. The front window and door was open along with the side window. The cab filters would be found to be plugged and the air mix door was stuck. The training for the operator was that fact that the AC unit only had the capacity to cool the cab, and not whole outdoors. Basically they had a choice, close things up or forget about the AC.

I also keep seeing a reference to a TXV or what is known as a thermal expansion valve. I worked quite a bit with those kinds of valves when I was in the navy. We had huge chill water units and a couple of big freezers that used them. When I got out and started working with auto and equipment units like Red Dots and such, I found out that they didn't use TXVs. All they had was an orifice and the switching worked purely on pressure.

I don't mean to be blunt but if I were the service manager and it was found that the compressor is working properly, the pressures are at specification, the evaporator and condensers are clean and the receiver dryer wasn't plugged, then there is nothing wrong with the system. The more likely issue is the interpretation of how the system is supposed to work. Interpretations and opinions are not a warranty issue.
Yes, the door and windows are closed.

As far as the air recirculating, there is no switch for that but there is foam panel on the hvac side cover.

This machine does use and expansion valve and they say that they checked it and it's working properly.

If you go by the service manual, the vent temps and the compressor pressure is not within specs. In the videos I sent the link to the vent temp is about 55 at around 86 degrees outside. Specs are 36 to 53. I haven't checked the compressor pressures since I got it back this time but after the first service it was about 20 on the low side and 165 on the high side and the vents were at 60 degrees. After the second service at 98 degrees out, humid and running for over 30 minutes at full throttle the low averaged about 24 and the high 200. The pressures were better for the first few minutes, L-29 and H-225, that's probably what the dealer is going by. The service manual says that between 86 and 101 degrees the Low should be 15-33 and the High 210-265.

There are times when the vent temps have gotten down to around 50, but they also seem to fluctuate at times between 50 and 58 or so.

The vents didn't leak any water until after the second service. There is a lot more water now after the 3rd service.

As far as I know, all they have done for service is hook it up to a machine and remove and put the freon back in. They also removed 1 drain valve on the second service and another one on the third service. I think they added dye to the system to check for leaks on the 2nd service.
 

Doug580l

Senior Member
Joined
Apr 15, 2018
Messages
301
Location
Southern Illinois
John C pretty much covered my thoughts on the water in cab and the operational characteristics.
Where I really get lost is that adding refrigerant made no change, good or bad.

Heck, if I leave the fan clutch activated on my peterbilt, and the ac on while idling, on humid, hot days, water will actually condense on the dash panel and the hvac box itself.

And, every modern mini machine, excavator, skidsteer, or compact track loader here has an hvac system with compromises that make them inefficient or slobbery, or weak on some days, and, we never, ever run the machines with the doors and windows closed.

I'm not saying the ac is right, but, nowhere have I seen verification of the cutout temp on the anti-icing switch, nor am I familiar with how the hvac box is constructed.

Cat puts unloader nipples in the large excavator HVAC drain tubes, that always clog with dirt buildup, so much so that I've removed them. Left clogged, water will come out the vents.
And Takeuchi excavator hvac boxes have the blower so low in the housing that condensate can spit out the vents when working on slopes.

One of my TB180FR machines (I has 4) has similar temperature issues, and I'll be replacing the anti-icing switch as soon as I feel like driving 4 hours to that empty (waiting in materials) jobsite.
One thing I will say about this machine is that the blower is very strong. Seems almost double of what my other machines are. The downside is that it needs to be on the highest setting if it's much over 80 degrees and humid out. And it blows water in my face and eyes. I'm pretty sure that there is no icing going on. There isn't a lot of water draining If I turn the ac off after running for hours.
 

Doug580l

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Joined
Apr 15, 2018
Messages
301
Location
Southern Illinois
Maybe it's a temp difference here but my Volvo 210 and my Deere 319 I can run with the door closed all day long without an issue, on the hottest of days the Deere a/c can't quite keep up but it's close. I can't say i've ever seen water come out the vents even with a/c on full for hours on end. However 90f is a really hot and really rare day here, generally cooler then that. My Takeuchi 153 a/c is completely useless, i've never even bothered with it, but it's also a 2006. If I was buying a 2022 i'd expect to be able to close everything up and the a/c keep the cab comfortable, I wouldn't buy any machine that wasn't capable of doing that. I don't think it's a lot to ask, a vehicle has been able to have a/c so cold at the hottest of days it'll freeze you out for over 20 years why can't equipment be capable of keeping the cab comfortable? The smaller machines have tiny cabs, it's not a lot of space to cool.

The thing I don't get is, if the system is working fine, why wouldn't the dealer show him another machine so they can say "see it's working exactly the same as yours" and it would be case closed.

One thing you could look into is tinting some of the windows. I tinted the rear one on my mini when it broke, it helps a bit. Could tint both side windows, i'd imagine it would help quite a bit.
As far as another machine, they said they do have another one there and it was blowing a few degrees colder than mine, but they also told me when they dropped it off that all machines are a little different and mine is within specs so they "can't" do anything.

I mainly got this machine to use instead of a beaten up 1997 case 580. It's got a bent door on it with a big air gap in it and the cab is probably 3 times the size of the mini and it cools better than the mini.
 

Tinkerer

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May 21, 2009
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The shore of the illinois river USA
Yes and no.
The dealership also. They may have used recycled crap.
Out of desperation I would drain it, do a good vacuum on it and put the correct refrigerant back in, with the exact amount specified in the service manual.
 

heymccall

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Feb 19, 2007
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Location
Western Pennsylvania
With a TXV system, the anti-icing switch is what cycles the compressor, well, to prevent icing. But, it is also the main regulation of the evaporator temperature.
On my TB180FR that has underwhelming AC performance, the anti-icing switch is cutting out the compressor long before the evaporator is anywhere near cold enough. Jumper the switch and it'll go 40° vent temps on a 90° day, until it ices over, which is usually less than an hour, if it's any kind of humid out.
 

fastline

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Aug 8, 2011
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Read back through all that I have put into this thread! I won't retype it. You seem to want to just "change parts", convinced that will solve something. What are you fixing? You don't know! You are also fixated on "vent temps", and I already covered how that mentality is flawed. Either add charge under careful monitoring of temps, pressures, and ounces of charge, or take my other route and blow up the phone! If I need in, and someone won't open the front door, I will go to the back door, then windows, then kick in a door.

As I mentioned, the water issue is separate and should absolutely be the focus of any dealer convos because it is NOT NORMAL!!! It will require that the AC unit in the cab be opened to expose the evap coil and condensate drain system. It is only then that you will find what is going on.

Send your videos to Bobcat, and say, "is this what you call a quality machine??? You didn't provide goggles with my new machine delivery"

You also have a heater core in there and someone already mentioned to ensure that is not causing issues. All you have to do is pinch off the lines to it somewhere, actually just one and it will stop any flow to it, and see if things improve. No need to replace anything.
 

fastline

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With a TXV system, the anti-icing switch is what cycles the compressor, well, to prevent icing. But, it is also the main regulation of the evaporator temperature.
On my TB180FR that has underwhelming AC performance, the anti-icing switch is cutting out the compressor long before the evaporator is anywhere near cold enough. Jumper the switch and it'll go 40° vent temps on a 90° day, until it ices over, which is usually less than an hour, if it's any kind of humid out.

Your asking for compressor damage doing stuff like that! part of the reason to cut out the compressor is to ensure there is enough superheat to protect the compressor. A TXV is specifically trying to achieve constant superheat. But I realize in many industries, the motto is "it's fine.....until it isn't".
 

suladas

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Agree with others, do not just start replacing parts. They will void your warranty on it, and blame the issue on you. And it's unlikely to fix the issue. If you want to spend money on anything, get an experienced a/c guy to look at the system to see if he notices any issues and get his thoughts on how it preforms. I would also be hounding bobcat to do something better. One machine to the next if exactly the same should be very similar.
 

heymccall

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Your asking for compressor damage doing stuff like that! part of the reason to cut out the compressor is to ensure there is enough superheat to protect the compressor. A TXV is specifically trying to achieve constant superheat. But I realize in many industries, the motto is "it's fine.....until it isn't".

The bypassing is/ was done while testing only on my TB180FR while the hvac was opened for cleaning.

But, I have encountered it several times where the anti-icing switch remained closed on my Kenworth W900 trucks (at least 5 times) and I still haven't replaced any of the compressors.
 

Doug580l

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Apr 15, 2018
Messages
301
Location
Southern Illinois
Yes and no.
The dealership also. They may have used recycled crap.
Out of desperation I would drain it, do a good vacuum on it and put the correct refrigerant back in, with the exact amount specified in the service manual.
Might be worth a try. It is interesting that each time it was serviced, they said they removed and put the freon back in with their machine and each time I got it back the ac worked differently.
 

JD955SC

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Mar 13, 2011
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The South
Might be worth a try. It is interesting that each time it was serviced, they said they removed and put the freon back in with their machine and each time I got it back the ac worked differently.

Their AC machine’s scale and charging system could be on the fritz as well. I know ours is a 20 year old piece of crap that has to be worked on yearly
 

Doug580l

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Joined
Apr 15, 2018
Messages
301
Location
Southern Illinois
Read back through all that I have put into this thread! I won't retype it. You seem to want to just "change parts", convinced that will solve something. What are you fixing? You don't know! You are also fixated on "vent temps", and I already covered how that mentality is flawed. Either add charge under careful monitoring of temps, pressures, and ounces of charge, or take my other route and blow up the phone! If I need in, and someone won't open the front door, I will go to the back door, then windows, then kick in a door.

As I mentioned, the water issue is separate and should absolutely be the focus of any dealer convos because it is NOT NORMAL!!! It will require that the AC unit in the cab be opened to expose the evap coil and condensate drain system. It is only then that you will find what is going on.

Send your videos to Bobcat, and say, "is this what you call a quality machine??? You didn't provide goggles with my new machine delivery"

You also have a heater core in there and someone already mentioned to ensure that is not causing issues. All you have to do is pinch off the lines to it somewhere, actually just one and it will stop any flow to it, and see if things improve. No need to replace anything.
I know I am fixated on vent temps and pressures. That is the only argument I can use with the dealer to try to get them to fix it since those specs are in the service manual.
If I do replace the freon as Tinkerer suggested I will first add some to see if it makes a difference this time.
I did email the link to the videos to the dealer. Not surprisingly no reply.
My wife contacted Bobcat on Facebook today and sent them the videos. They replied and said that someone will contact me. Trying not to get my hopes up, lol.
I didn't crimp the hoses to the heater core, but I did check the temperature of it with the machine running for a while and it was about the same temp as the surrounding area.
 
Last edited:

Doug580l

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Joined
Apr 15, 2018
Messages
301
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Southern Illinois
Agree with others, do not just start replacing parts. They will void your warranty on it, and blame the issue on you. And it's unlikely to fix the issue. If you want to spend money on anything, get an experienced a/c guy to look at the system to see if he notices any issues and get his thoughts on how it preforms. I would also be hounding bobcat to do something better. One machine to the next if exactly the same should be very similar.
I was thinking about hiring someone to check out the ac system. I've been happy with my Case dealer and might call them to see if they would diagnose it.
 

fastline

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I was thinking about hiring someone to check out the ac system. I've been happy with my Case dealer and might call them to see if they would diagnose it.
That would be pure GOLD!!! While it is at the Case dealership, make sure to snap a few pics, post them on Bobcat's FB page saying, "this is how good Bobcat stands behind their product. The guys at Case are a little smarter, they will figure it out"........

Seriously, I would TOTALLY blast their FB page!!! Before they can even take it down, thousands will see it. Unfortunately this is how anything gets done anymore. Internet blasts.......
 

John C.

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I'm guessing then that your system is either on or off? If that is the case, there is no TXV.
 

Doug580l

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Apr 15, 2018
Messages
301
Location
Southern Illinois
That would be pure GOLD!!! While it is at the Case dealership, make sure to snap a few pics, post them on Bobcat's FB page saying, "this is how good Bobcat stands behind their product. The guys at Case are a little smarter, they will figure it out"........

Seriously, I would TOTALLY blast their FB page!!! Before they can even take it down, thousands will see it. Unfortunately this is how anything gets done anymore. Internet blasts.......
Lol, that's a great idea!
 
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