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carlday1, Home Appliance Technician
Category: Appliance
Satisfied Customers: 381
Experience:  I have 5 years experience in repairing and maintaining small domestic appliances.
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I have a vehicle fitted with a Danfoss air control valve,

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I have a vehicle fitted with a Danfoss air control valve, it's worked for 10 years, it has two incoming 6mm air pipes and electrical wiring for switching the compressor. One air pipe is fitted to a diaphragm which appears to tip the switch when set pressure is reached and this tipping action breaks the electrical supply to the compressor, fine.
There is a small extension to this tipping mechanism which depresses a needle valve in the second air inlet pipe, in the past this was heard as a short sharp 'siss, now the needle valve remains open and dumps the air generated in the system. Questions ..... What is the purpose of the needle valve piping and assembly? Because if I was to cut this little arm off the valve could not depress and exhaust!

I don't recognise those numbers, but the description sounds like you are talking about a pressure relief. If this is a pressure relief, do not alter it, but if you can get it identified and replaced as altering it in any way could put the system in jeopardy.

Customer: replied 1 year ago.
I have your reply, you obviously don't know the answer and presumably are not interested in finding the solution. For your information! there is no adjustment point to the valve. Please do not take any payment from my card, I will have to seek expert advise elsewhere .
Regards, ***** *****

HI Michael,

My name is ***** ***** I will help with your question. I have attached the datasheet to this chat thread to see if that helps you. I am still working on your question and will get back to you soon. Let me know if it is the wrong datasheet.

Customer: replied 1 year ago.
Hi Carl, just got your reply to my problem, the data sheet is correct,well done, the bit that is causing the problem is component 22, the arm drops onto the needle valve and exhausts the system when the other end of this bit rises and breaks the electrical supply to the compressor. I don't know if the needle valve can be adjusted? If so it does not look obvious , or maybe the valve needs replacing? Your Call
Michael Borrill

Hi Micheal,

I don't think the needle valve can be adjusted and I don't know if you would manage to get just the needle. You can get a replacement valve for <£50 maybe worth considering changing the whole pressure switch.

I will see if I can find a replacement needle and get back to you if I can source one. Does the valve have any more numbers after 022?

carlday1, Home Appliance Technician
Category: Appliance
Satisfied Customers: 381
Experience: I have 5 years experience in repairing and maintaining small domestic appliances.
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Customer: replied 1 year ago.
Hi Carl, the No. 22 is the component number shown on the data sheet you supplied, the number stamped into the actual needle valve is AB 385, where canI buy. Complete valve from?I am perplexed by this needle valve, it is attached via a dedicated 6 mm pipe to the same line as the other pipe operating the diaphragm. It never gave any problems in ten years, so I never bothered to ponder what it actually does?I am minded to remove the valve and see what happens, I can see that the valve will allow the system to reach pressure and then turn off the compressor without depressing the ( removed valve) but how does it relieve pressure ? This was my original question, because if you can explain how this valve is supposed to function I can the investigate and decide if adjustment or replacement is necessary. I think you are doing a good job for me, so we are on the same side here.Best regards, Michael
Customer: replied 1 year ago.
Hi Carl,
I have found the problem, the valve was not at fault, for your information, the second air supply pipe entering the valve via the needle valve is , as described, a pressure relief valve.
It is required to drop the pressure in the air line adjacent to the compressor in order to lower the initial load on the compressor as it stars up. So the line up is, compressor, 'T off' to needle valve, non-return valve, then on to receiver etc. And guess what? The non return valve was stuck, thus not allowing the compressor to decompress and discharging the system.
I am pleased with the help you did supply, I can use this for reference in the future. I note that you want to make a charge of £15, I'm happy with that, so go ahead and charge our card.
I will consult your services again should the need arise, best regards,
Michael Borrill