Bentley Turbo R 1989 AC issue - Rolls-Royce and Bentley Forums
 
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post #1 of 10 (permalink) Old Yesterday, 03:42 PM Thread Starter
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Bentley Turbo R 1989 AC issue

I bought my car 6 months ago as a project car and 6 months later it was ready to go, mainly reconditioned the complete interior but didn't do much to the engine other than the serviceable parts like oil, plugs filters, belts and topped a little bit of gas as my ac wasn't cooling. My system is still working on R12 but i manged to get a cylinder of 415B gas from a friend which is a direct replacement to the R12, the AC cooled very well in fact even took the temperature down to 8 deg C when sensor was put into the air vent. I took the car out for her first stroll while the ambient temperature was approximately 32deg C, the ac was cooling well for the majority of the short trip but after i stopped the car for about 10 min to speak to a friend and drove again the ac air wasn't cool at all, i though that the gas leaked again, what i noticed is that the ambient temp gauge on the centre console wasn't giving the right temp as it nearly touched the 40 deg.
The next day i decided to drive the car again this time it was in the evening and the ac worked very well and didn't stop cooling, this was the evening so ambient temp was around 27 deg. Could it be that the ac stopped working due to the ambient temp gauge wasn't reading the right temp, where is the sensor that gives the reading to this gauge?
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post #2 of 10 (permalink) Old Yesterday, 06:16 PM
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The expansion valve may have frozen, preventing refrigerant from circulating.

Did you use a manifold set to add the gas? You may have overcharged the system.

LRL-41587C
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post #3 of 10 (permalink) Old Today, 02:49 AM
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Quote:
Originally Posted by Wraithman View Post
The expansion valve may have frozen, preventing refrigerant from circulating.

Did you use a manifold set to add the gas? You may have overcharged the system.
Roger.

I agree with the post above, check pressures in the A/C system.

The ambient temp gauge has nothing to do with the A/C system and should be ignored in this case.

Jake.
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post #4 of 10 (permalink) Old Today, 03:39 AM
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Hi Roger
Mine did this once, just switching off the ignition and back on started working again, think the ecu gets locked up OK
Mike

chassis 27650
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post #5 of 10 (permalink) Old Today, 04:29 AM
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Hi,


Just topping up an air con system can be difficult to ensure the correct weight charge of gas in the system.


The way I always do it is using the sight glass in the receiver dryer (if it has one).


I always top up through the low pressure line and ensure the bottle is the correct way up for supplying gas and not liquid into this line.


It is important too to purge the pipe being attached to the bottle and before attached to the car so no air is introduced into the system. With the engine running as gas is being drawn in from the bottle and line pressure increases the clutch should first click in and start the compression and flow.


Watching the dryer sight glass it should start showing bubbles in the liquid and then clear to just liquid. At this point I shut off adding anymore gas into the system.


Obviously lots of problems can cause issues with the system, indeed many cars I have seen the receiver dryers break down and put particles into the liquid which get trapped at the expansion valve.


A lot can often be assessed by feeling the heat/cool of pipes at certain points along the system too.



All these sort of problems do require a complete discharge and any parts replaced, then a vac and hold before putting back the correct charge weight.


I had not realised though later cars had an ecu in the circuit.......glad all my classic cars are pre the voluminous use of ecu's everywhere today. I would rather deal with all the Lucas LRA relays


Steve
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post #6 of 10 (permalink) Old Today, 05:12 AM
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Hi Steve
I didn't know SY's and early SZ's didn't have an aircon ECU lol
They appear in the 20000 series cars ECU is £360 !!
Mike

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Last edited by mikebentleyturbo2; Today at 05:15 AM.
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post #7 of 10 (permalink) Old Today, 05:49 AM
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Mike,


Thankfully the early SY cars just had a 'suction throttle valve' (STV) in the line connected to a Lucas stepper motor (as used on control flaps etc) which varied the performance of the air con output.


Obviously it was not precise as later cars now and just controlled manually with a variable position switch on the console linked to the stepper motor. (I like that).


The STV did have its own problems though with the diaphram and leaking so many cars you will see them just blanked off so permanently on full flow.


These sort of cheap fixes just cannot easily be done with ECU's


All the best


Steve

Last edited by Steve E; Today at 05:56 AM.
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post #8 of 10 (permalink) Old Today, 08:07 AM
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R-415B refrigerant gas comes out of China. It is not compatible with R-12., only R22 and R152a.
Your system should be evacuated, vacuum checked, and the drier replaced. There is a chance the new refrigerant does not bode well with the compressor oil and the seals currently in the system.

You would have been better off doing a R134a conversion.
I converted my 1980 Silver Wraith II to R-134a.

LRL-41587C
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post #9 of 10 (permalink) Old Today, 08:46 AM
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Hi,


Must admit I had not heard of R415b, so before previously posting my last response I thought I would google it and check.


I did find quite a few threads stating it was OK for a 'replacement' and compatible with R12 systems so just ignored making any comment on it.


I use R309 as a 'drop in' for R12 systems and have done now for several years on my car as I have a large bottle still.


Not sure even if if R309 is still available or even legal but I got it from my brother in law 10 years ago who was a refrigeration engineer for large supermarkets.


Well worth another thorough check out then on R415b compatibility to actually be mixed with R12 gas or if it means it can be used OK as a complete system substitute.


Hope for the best


Steve

Last edited by Steve E; Today at 08:49 AM.
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post #10 of 10 (permalink) Old Today, 02:59 PM Thread Starter
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Thanks all for your interesting replies, today i took her out for another spin and ac worked very well at one point i had to switch it off as wife was complaining she is feeling cold, yesterday i connected the manifold and realised a little gas so i think saying that system was slightly over charged makes sense.
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