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Help Diagnosing Air-Con


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#1 will_nic

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Posted 22 November 2020 - 04:48 PM

Hi all,

 

I have a 95 SPi Mini which appears to have an aftermarket air con unit fitted. The car was UK built and then spent sometime in Japan (where I believe the AC unit was fitted - however I am just guessing).

 

Since I have owned the car the AC has never blown cold air, but I'd like to get it working. I have no experience with AC, but I'm hoping for a few tips to help try diagnose the issue.

 

I have attached some photos of the unit.

 

What I know:

  • The fan speed dial works and does control the speed of the blower - pushes out ambient temp.
  • Temp dial does not change temperature
  • By memory the AC compressor clutch does engage when the unit is turned on
  • I dont know if it has enough or any refrigerant in the system
  • Sticker on compressor states refrigerant 'R12', which I believe is now illegal?

 

From doing a bit of reading the thermostat sounds like a common issue... could this be the problem in my car? Where would I find it and test it?

 

Thanks so much in advance,

Will

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#2 Cooper Mac

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Posted 22 November 2020 - 06:34 PM

I'm going through a similar project with my 205 GTi's A/C!

 

You are correct, R12 cannot be used anymore, so you will only be able to use R134a, BUT to use this gas, you will need to change all of the  o ring seals in your current system as these are not compatible with the original O rings. If you don't change them, the gas will just leak out!

 

Usually there is a pressure sensor in the system, which prevents the Clutch from engaging if there isn't enough gas in the system. If your clutch does engauge it is either because there is enough gas in the system, or the pressure sensor is faulty.....

 

The fan speed should work independently of the A/C electrical circuits, so what you have seen if OK.

 

I would check that the clutch is engaging, if it isn't that that will be why you don't have and cold air! If the couch is engaging, but you are not getting any cold air, then I would assume that it is the Pump, which isn't pumping...... 



#3 will_nic

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Posted 22 November 2020 - 06:41 PM

I'm going through a similar project with my 205 GTi's A/C!

 

You are correct, R12 cannot be used anymore, so you will only be able to use R134a, BUT to use this gas, you will need to change all of the  o ring seals in your current system as these are not compatible with the original O rings. If you don't change them, the gas will just leak out!

 

Usually there is a pressure sensor in the system, which prevents the Clutch from engaging if there isn't enough gas in the system. If your clutch does engauge it is either because there is enough gas in the system, or the pressure sensor is faulty.....

 

The fan speed should work independently of the A/C electrical circuits, so what you have seen if OK.

 

I would check that the clutch is engaging, if it isn't that that will be why you don't have and cold air! If the couch is engaging, but you are not getting any cold air, then I would assume that it is the Pump, which isn't pumping...... 

 

Thanks!

 

Replacing all the o-rings sounds like a big job right? Sounds like something which would be best suited to a AC pro... any suggestions for someone in the midlands?

 

I did wonder if the AC system was drained of gas before it was re-imported into the UK?

 

I will check the compressor clutch this week and report back.

 

Cheers,

Will.

 

Also, good luck with the 205 project!



#4 Cooper Mac

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Posted 22 November 2020 - 06:56 PM

The O rings are not too much of a problem (famous last words!) as they will just be on each pipe connection. It's easy for you to do yourself, fortunately the gas had been long gone from my 205, so there was no problem opening the pipe connections and changing the O rings. I got an A/C O ring selection pack off eBay, they are green in colour if that helps?

 

I managed to finish my A/c off and take it to get recharged and tested, but sadly during the pressure test one of the original pipes burst, not a problem other than it is the only one I can't easily get to! I did manage to get an original pipe (a challenge when there were only a handfull of UK 205s that came with A/C!), but fitting it requires removing the front end of the car......



#5 will_nic

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Posted 22 November 2020 - 07:06 PM

The O rings are not too much of a problem (famous last words!) as they will just be on each pipe connection. It's easy for you to do yourself, fortunately the gas had been long gone from my 205, so there was no problem opening the pipe connections and changing the O rings. I got an A/C O ring selection pack off eBay, they are green in colour if that helps?

 

I managed to finish my A/c off and take it to get recharged and tested, but sadly during the pressure test one of the original pipes burst, not a problem other than it is the only one I can't easily get to! I did manage to get an original pipe (a challenge when there were only a handfull of UK 205s that came with A/C!), but fitting it requires removing the front end of the car......

 

Hmm, yeah that's my concern. As you can see from the pic's there isnt much space in the engine bay with the A/C haha! I'll have a better look this week.

 

Bummer about the burst pipe on the 205!



#6 will_nic

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Posted 23 November 2020 - 03:13 PM

 

 

Alright, so I have tried to see if the AC compressor clutch engages. As far as I can tell it does not. I didn't hear a click or anything when I turned the blower on inside the car, also no change in engine idle. Here is a video as I turn the blower unit on. Listening to the video I can't hear anything either. 

 

I guess my next best bet is to take it to someone to see if there is pressure/refrigerant in the system? 

Is there anyway to test the pressure switch and rule that out first? And where would I find this?

 

It was blowing cold air today, but that was only because it was freezing in the garage haha!

 

Cheers,

Will.


Edited by will_nic, 23 November 2020 - 03:13 PM.


#7 Cooper Mac

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Posted 24 November 2020 - 11:50 AM

The Clutch isn't engaging, so it is possible that the system isn't seeing any pressure, or the clutch is NFG! 

 

I don't know anything about the A/C setup on Minis, but if there is a plug on the Compressor pump (there must be so you can remove / swap the pump), then you can remove this and but 12 volts across it to check that the electro magnetic clutch is working. You will need to do this with the engine switched off. If it is working, you will hear and see it move within the pully. It is possible that is it hasn't been used for a while that it might need freeing off with some small taps to the pulley. If the clutch works then it either isn't getting the signal from the A/C control, or the gas is low / gone.

 

The only way to safely check the gas situation is to take it to an A/C specialist so they can check it for you. If there is gas in there, but not enough it would also be safer for them to remove this for you, then you can change the seals and check the system ready for re-gassing!



#8 will_nic

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Posted 24 November 2020 - 12:32 PM

The Clutch isn't engaging, so it is possible that the system isn't seeing any pressure, or the clutch is NFG! 

 

I don't know anything about the A/C setup on Minis, but if there is a plug on the Compressor pump (there must be so you can remove / swap the pump), then you can remove this and but 12 volts across it to check that the electro magnetic clutch is working. You will need to do this with the engine switched off. If it is working, you will hear and see it move within the pully. It is possible that is it hasn't been used for a while that it might need freeing off with some small taps to the pulley. If the clutch works then it either isn't getting the signal from the A/C control, or the gas is low / gone.

 

The only way to safely check the gas situation is to take it to an A/C specialist so they can check it for you. If there is gas in there, but not enough it would also be safer for them to remove this for you, then you can change the seals and check the system ready for re-gassing!

 

Cool, thanks man. I'll give it a shot.

 

Cheers,
Will.



#9 xrocketengineer

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Posted 24 November 2020 - 07:05 PM

It is probably better to take it to a professional. The O rings themselves might survive the changeover if they are in good shape however, the issue is that R12 uses petroleum based oil and R134a uses synthetic oil. The R12 oil residue can react with the 134a refrigerant and become corrosive. So, the compressor and accumulator have to be removed and drained then flushed like the rest of the system. At this point most of the components have been removed and there is no point on reusing old incompatible O rings. In most cases the accumulator is replaced too.



#10 will_nic

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Posted 26 November 2020 - 10:43 AM

It is probably better to take it to a professional. The O rings themselves might survive the changeover if they are in good shape however, the issue is that R12 uses petroleum based oil and R134a uses synthetic oil. The R12 oil residue can react with the 134a refrigerant and become corrosive. So, the compressor and accumulator have to be removed and drained then flushed like the rest of the system. At this point most of the components have been removed and there is no point on reusing old incompatible O rings. In most cases the accumulator is replaced too.

I agree. Not something I particulary want to go wrong. When I get the chance I'll take it to a pro.

 

Cheers for the help all.



#11 Aria Aradhea

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Posted 27 November 2020 - 07:42 AM

Yes, the clutch is not engaging. Check if you have enough gas in the system and that it is not leaking somewhere.

 

The thermostat is a common problem because of the position of its location (above the ac fan blower) that tends to kink the cable, but usually will work if it set on the maximum cool position although will cut off often. 



#12 Bobbins

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Posted 27 November 2020 - 01:15 PM

It's hard to tell from the first photo, but on my '98 Mini the air-con accumulator is fitted directly over the o/s subframe tower bolt therefore needs to be removed to access the bolt and change the tower rubbers. If the air-con is degassed and having the seals renewed it's wise to take the opportunity to replace the subframe rubber mounts at the same time.



#13 will_nic

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Posted 01 December 2020 - 05:32 PM

Thanks guys. I ran 12v to the AC clutch and it did engage (with engine off), so I suspect the system has been degassed, or doesn't have enough.

 

I need to take it to an AC specialist for them to check if there is any refrigerant in the system. I'll hopefully do that once we are out of lockdown.

 

As for the accumulator, I believe my is mounted under the condesor. I recently had to unbolt the subframe and there were no obstructions thankfully.

 

Cheers,
Will.






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