Air conditioning compressor worn out?

[.RC.]

I have a problem with my air conditioning. I have recharged it, but it gets mildly cool. With the gauges on it, the pressure on the low side only starts dropping, with the high side rising only when the engine is run flat out. At idle both pressures go back to static level, like the compressor is only working at higher RPM's.

Is this a sign the compressor is cactus?

 

[ahart]

When you evacuated the system did you change the drier? If the internals of the compressor are worn or coming apart, I would expect to see that in the oil and the dryer. If the oil was clean then I would suspect the clutch has failed and isn’t driving the compressor properly. Is there a removable cover on the clutch?

 

[56wrench]

I assume the drive belt is tight and not glazed from slipping?

 

[OzDozer]

It's pretty important that receiver/driers (or dessicant bags) are replaced when you regas, as they get clogged up with moisture and oil from the compressor.

Just did a dessicant bag on one of my Ford Rangers after an A/C compressor seized up, and I was surprised how filthy it was.
Also, you could put some dye in the system to see if you can pick up any leaks, the o-rings on the pipe connections flatten out and that's where leaks start. Plus, the carbon seal on the compressor shaft will wear with age, and release gas.
Long periods of A/C inactivity are also bad for carbon compressor seals, they dry out and then leak, as well.

 

[Old Doug]

Any time your working on a ac the more stuff you replace the better. I wouldnt think twice about the compressor i would replace it.

 

[.RC.]

Thanks. I have a new drier here, not installed yet. I have found a very reasonably priced genuine Sanden compressor on ebay, NOS from OzDozerland. So will put that on when it turns up.

I will also pull all the hoses off and flush the hoses, condensor and evaporator. Did that with my tractor some time ago and got a bit of crap out of it.

 

[Vetech63]

Isn't it Winter there yet?

 

[OzDozer]

RC, you should've PM'ed me, I have a selection of older model, NOS, genuine Sanden compressors on hand. What model number is your compressor?

Vetech, we're just heading into the start of Summer, it's "fix-the-A/C" time of year, right now.

 

[56wrench]

I assume you know to add the appropriate type and quantity of refrigerant oil to the replacement compressor and to the new receiver/drier before installation and after flushing? Also some more to the hoses, condenser and evaporator? If doing a complete flush, the service manual for your machine should list the quantity of oil in the complete system. Before you condemn the compressor, make sure your expansion valve is working correctly, also that the evaporator and condenser fins are clean

 

[.RC.]

Well there is nothing in the cat service manual about the air conditioner, other then how to pull the hoses and stuff out. The compressor should be pre-charged with the appropriate amount of oil.

As for gas. I have someone who can fill it with R134A, but he is going through a tough time at the moment so do not want to annoy him. In this country we can not simply buy R134A due to the air conditioning trade years ago lobbying the government to ban anyone except the people that pay them to be part of their little group from being able to buy any greenhouse gas refrigerant. But anyone can go and buy cans of freeze spray or air duster which is all R134A and spray it around willy nilly.

We can buy a direct R134a replacement propane blend gas and use that. I do have it here. It runs more efficiently then R134a as well.

 

[OzDozer]

There is likely to be nothing in the Cat service manual about the A/C system, because it has been installed as an aftermarket addition by an independent A/C system retailer/installer.

If you can find a local auto electrical business, many of these also deal with A/C systems.

To find out the required amount of oil for your compressor, go to Highgate site, they have lots of Sanden compressor technical info, and a heap of downloads of other technical A/C info.

Click on "News & Tech", then "Downloads" in the drop-down menu.

Compressors usually take between about 125cc and 200cc of compressor oil. Some new compressors come already filled with oil, some don't.
You also need to check on the specific type and grade of oil required, there are several types of oil and several grades available.

Home Page

www.highgateair.com.au

Compressor regassing is very tightly controlled in Australia, by the Australian Refrigeration Council, regassing requires a A/C licence, and you have to record the amount (grammes) of refrigerant extracted and the amount replaced, and those extractions and regassing events must all be reported to the authority.
You are not allowed to release any refrigerant to the atmosphere, nor is "topping up" allowed.

https://www.arctick.org/media/1186/arc_fact-sheet_15.pdf

 

[.RC.]

I forgot to mention the compressor is the common SD7H15 24V double A pulley. They are that common they can be got dirt cheap ~AU$120 for the cheapest of the cheap chinese versions. https://www.vevor.com.au/air-condit...508-style-chrome-plated-v-belt-p_010846989598

 

[Cmark]

Compressor regassing is very tightly controlled in Australia, by the Australian Refrigeration Council, regassing requires a A/C licence, and you have to record the amount (grammes) of refrigerant extracted and the amount replaced, and those extractions and regassing events must all be reported to the authority.
You are not allowed to release any refrigerant to the atmosphere, nor is "topping up" allowed.

Shocking isn't it. And having a refrigerant handling license isn't enough. You then need a second "Trading" license to be able to buy the gas. About $360 per year all up.

 

[.RC.]

So about an hours work to pay for the licence.

 

[OzDozer]

That Vevor A/C compressor is a steal at that price - and the Chinese stuff from Vevor is mostly reasonable quality, too.

I just blew an A/C compressor on one of my Ford Rangers - but because Ford use Halla A/C compressors, I was still shafted - even by the Chinese.
I ended up getting a Chinese Halla compressor through AliExpress, but it still cost me AU$320.

However, they did airfreight it for that price and I had it in my hands in 5 days - faster than Vevor delivers within Australia.
The local importers were still wanting AU$360 for the Chinese compressor, so I did save myself AU$40.
Any genuine Halla compressor seller was wanting around the AU$600 mark.

One of the problems with doing regassing yourself is you have the cost/time of the training course, the cost of the regassing equipment and bottles, the cost of keeping items such as TX valves and Schrader valves, pipe seals, receiver/driers or dessicant bags - and then there's the reporting paperwork as well.

I find there's enough A/C repair people about, that it doesn't take long to find an A/C repair person - and in cool weather, most are looking for more work.

 

[56wrench]

It would appear as though the refrigeration industry there basically has a licence to print their own money

 

[OzDozer]

I can get an A/C serviceman to de-gas and re-gas the average car A/C for around AU$110 to AU$130. I don't consider that unreasonable, and they will often replace any leaking o-ring seals or Schrader valves in that figure.

I've already got too much equipment that's "needed" for jobs I might do once a year or even more, so I'm happy enough to pay an A/C serviceman for fixing my A/C.

Plus, they generally have a lot of A/C experience and can go right to the specific problem that is peculiar to the individual vehicle.

And if he doesn't fix it properly, I can call him back, and he can fix it again for no extra!

Last A/C guy told me how he had a client who wanted to replace his Mercedes car A/C condenser himself, to try and save some money.
A/C man agreed, de-gassed the clients Mercedes, client went away, fitted his new condenser himself, and brought the Merc back to be re-gassed.

A few weeks later, he calls the A/C guy and says, "My A/C is not cold any more? What did you do wrong?"
A/C guy said, "I did everything right, are you sure you fitted the new condenser properly?"
Client says, "Oh yes, it was a terrible job to fit it, everything jammed in there, but I did it right!"

A/C man says, "Well, bring it back then, I'll check it out".
A/C man checks the system, finds a hole in the new condenser. Client refitted everything in a hurry, and jammed a wire between the fan motor frame, and the new condenser.

It all worked fine for a while, but vibration over several weeks saw the jammed wire abrade the aluminium in a condenser tube, just enough to put a pinhole in it!

What was worse - the client had bought new condenser from Mercedes, and paid around AU$1500 for it!!

A/C man says, "I can get you a new aftermarket condenser for AU$300, and if you like, I can order it, and you can go pick it up, and I'll fit it properly for you!"

Client was stunned upon hearing this, and realised about then, his attempts to save money had achieved nothing.

He went and picked up the aftermarket condenser, A/C man fitted it for a couple hundred bucks, gassed him up again and client could not believe how little it cost. Mercedes dealer had quoted him AU$2,500 to replace the condenser!

 

[JD955SC]

Cats AC information is in a separate service manual”Heating and Air Conditioning R-134a for all Caterpillar Machines”