Air con not working

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johnny1901
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Air con not working

Post by johnny1901 »

Hello. My sister has a 2015 Peugeot 308 T9, 1.6 HDi 92HP. Air con blows warm i.e ambient. It was re-gassed about three months ago and worked fine for 3 months. Now it blows ambient air.
My sister claims that when it was regassed, the guy at the aircon specialist stated it did not actually need more than a few grams of refrigerant (1234yf). She just took it to Halfords for a free check, they connected pressure gauges and told her refrigerant pressure is fine.

I have Diagbiox. Diagbox states pressure with aircon switched off is 5.4 bar. When Aircon is switched on pressure goes to 9.5 bar in Diagbox. High and low speed engine fans work perfectly operating from Diagbox but do not come on when aircon is operated. There is 1 intermittent fault in BSI moduile: B132A 84: Air con low pressure circuit fault. Clearing this code does nothing. Aircon still does not work and engine fan does not come on even when this code is absent.

Disconnecting the pressure transducer on the aircon line in the engine compartment makes pressure rise to 10 bar. Re-connecting gives normal 5 bar air-con off, 9.5 bar when on. Repeated disconnecting several times, always gives same pressure result (so I assume pressure transducer is OK). Diagbox also shows compressor solenoid (its a variable displacement compressor with no clutch) climbs up to about 80% duty cycle. One of the pipes to the compressor gets cold.

OK. It may just need regassing and has a slow leak. This would explain why it worked after regassing and doesn't now. Simple. Problem is to know for sure you have to evacuate all refrigerant and re-gas...this costs around £100. And then it only tells me the car has a slow leak.

So my gut feeling tells me it has a slow leak. But I'm concerend guy at aircon place told my sister it didn't need more than a few grams when topped up 3 months ago and Halfords (don't laugh) say pressure is OK. I can't understand that when no codes are present, air con does not get cold. Engine fans do not come on. No other codes are present in Diagbox. It takes a few hours for the B132A 84 intermittent code to register in the BSI.

Has anyone else had a similar experience? Does it just need regassing (and therefore has a slow leak that needs finding). or am I missing something obvious? I have read on this forum B132A 84 means compressor is disconnected and this happens when pressure is below 2.5 bar (assume with variable displacement compressor solenoild will have zero duty cycle). Well I'm at 5.5 bar, and Diagbox shows 80% solenoid duty cycle. I cannot find anywhere an accurate description of why B132A 84 is displayed as a temporary fault code. Coments/suggestions welcomed.
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GiveMeABreak
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Re: Air con not working

Post by GiveMeABreak »

Ok, so here's the fault details and if there is any issue with the pressure the compressor will deactivate the A/C and that's why you won't be getting any cooling and subsequently why the fan isn't working with the A/C. The suspect areas do state the A/C pressure sensor or the harness as possible suspects:
Fault Code: B132A 84
Description of Fault: Air conditioning circuit low pressure safety fault: Signal below the tolerance range. Low pressure safety active (For more than 1 s).
Conditions for Fault to clear: Low pressure safety inactive
Downgrade Modes whilst Fault is active: -
Symptoms:
  • Malfunction of the production of cold air
  • Malfunction of the regulation of the requested temperature
  • Malfunction of the windscreen demisting/de-icing
Suspect Areas:
  • Air conditioning pressure sensor
  • Electrical harness
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johnny1901
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Re: Air con not working

Post by johnny1901 »

Thanks. Really appreciate that. Funny how it suggests air conditioning sensor or electrical harness but does not mention low refrigerant level. I would have thought this would have been first point mentioned. Since a new pressure sensor can be had for around £20, might be worth replacing it anyway.
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Re: Air con not working

Post by GiveMeABreak »

Not for this specific fault code - because the fault being triggered is related to the low pressure sensor.

The compressor will of course be disabled for low refrigerant levels, but as you have this specific code it is more likely to be the sensor. That's why fault codes can be very helpful in narrowing issues down.
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Re: Air con not working

Post by ozvtr »

If you can read the 'high side' pressures in diagbox then the sensor is working. Particularly if the pressures go up and down when the compressor cycles. If it didn't change at all you might be suspicious.
Not that familiar with 1234YF systems.
Vapor pressure for 1234YF is 6 Bar @ 21'C. If the day is hotter, the pressure will be higher. That's "static". I.E. the system at ambient temperature and the compressor not running.
So with the compressor running the pressures should be way higher, in the order of about 17 BAR!
You are probably getting a "temporary" fault because the static pressure is just at the low pressure cut off. The static pressure will go up and down with the temperature of the day. You might find that the compressor won't kick in in the morning, but it might work in the afternoon? Or the compressor will work on a warm day but not on a cool day.
The thermo fan(s) run proportional to the high side pressure. If the pressure is low the fan(s) wont run. And your pressure is low!

5.4 Bar static is a bit low but the high side pressures are definitely too low. Without seeing the low side pressures or knowing the temperature of the day, I couldn't say if there was a problem with the compressor or a blockage in the system. If it's already been re-gassed once before and that fixed it for a while then I would say that there is a leak in the system.
johnny1901
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Re: Air con not working

Post by johnny1901 »

Well I've ordered a new sensor and Ill see what happens. I agree that it sounds like a leak but it sporadically throws the B132A 84 code which references the sensor or wiring. Also when regassed my sister is adamant the guy said it only needed a few grams and was essentially full. Maybe having system on vacuum for half an hour made sensor work for a while. Halfords also attached gauges and said pressure was ok. Only real way to know if there is a leak is to evacuate and refill....and that costs £100. So will check sensor first, then probably inject dye to see if I can see a leak.
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Re: Air con not working

Post by ozvtr »

Use a mixture of dishwashing liquid and water in a squirt bottle (something like an old window cleaner bottle). About 30% dishwashing liquid.
Concentrate on the crimped fittings where the aluminium lines meet the flexible lines. I have found these joints leak after time.
However you can squirt this stuff all over the A/C system and look for leaks.
Is not always the case that you will find oil patches, particularly if it's a small leak.
ozvtr
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Re: Air con not working

Post by ozvtr »

johnny1901 wrote: 16 Aug 2023, 21:15 Only real way to know if there is a leak is to evacuate and refill....and that costs £100.
No, the system can be filled with nitrogen (which the A/C guys should have). Then check for leaks with soap and water. Or fill the system with a cheaper "detectable" gas and go over it with an electronic detector.
A good A/C company should be able to find the leak cheaply and easily.
johnny1901
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Re: Air con not working

Post by johnny1901 »

Sorry. I was not clear. What i meant was the only way to know for sure that there is insufficient refrigerant is to evacuate it and weight it. The pressure at idle is OK and Halfords connected gauges and said pressure was fine. I wonder how easy it will be to find a leak which takes 3 months to get to 5.5 bar, with washing up liquid. Nitrogen is usually used to find big leaks. If there is a leak on my sister's car, its very slow.
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Re: Air con not working

Post by Hell Razor5543 »

Normally, when the A/C is re-charged, a UV dye is added as part of the process. That way, using a UV light and goggles. it is possible to locate a leak in the A/C system. I know that, when DickieG recharged my A/C, he made sure the dye was added for that very reason.
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johnny1901
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Re: Air con not working

Post by johnny1901 »

Thanks for that. I didnt know dye is usually added. If the pressure sensor does not cure the issue (still waiting for it to arrive) then my next move would be to inject UV dye. Ill get my sister to check with the Air Con specialist if they added UV dye in the regas. If the did, I'll get a UV torch and take a look for leaks.