Weird aircon problem

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oscarloco
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Weird aircon problem

Post by oscarloco »

Hi
Mi aircon has been doing some crazy things. It seems that when the weather is very hot (around 27 - 30 Celsius) and I'm in traffic, the aircon disconnects as usual but when the signal to start is sent (I hear the relay), the rad fans do come in but the compressor doesn't. The weird thing is that if I switch off the blower, the compressor engages again. This works to some degree but then this doesn't work either.
Only if I switch off the aircon and leave if off a few seconds and then turn it on again while the car is deccelerating at around 2500 RPM will it engage again for a while.
Or if I get to a main road were I can keep a speed >60 kph the aircon will work fine.
I tought it was a lack of gas so I went to charge it but the techician told me that indeed it lacked some gas but not too much. I charged it and the problem improved but still, it doesn't work as it used too.
Any ideas?
splat
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Post by splat »

"Any ideas?"
Wind down the windows and open the vents. You've no right to expect an 11 year old Citroen aircon system to work!
alan s
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Post by alan s »

Oscar,
Has the guy who has checked the system also checked the head pressure or only the suction?
This sounds like too much pressure build up on the high side of the system and this can be caused through several things.
Overcharged with gas, air in the system, faulty HP cut out switch or a receiver dryer overdue for replacement.
Other causes can be worn brushes in the condensor fans; I got caught with this one on my '94 Xantia where one fan had worn out the brushes so after a while, the one fan cut out but the other kept going and I only found out about it by accident because the noise indicated both were operating.
Another and simple thing to check, is that there hasn't been a build up of dirt and leaves between the radiator and the condensor. This can be checked by slackening the radiator and blasting an air hose or preferrably a Karcher or Gerni down between them to blow the muck out. If there's not a good free flow of air through these two cors, this can cause the head pressure to go abnormally high and create problems when the system tries to bring it down using the fans. When driving, with a combination of fans and air passing through them, it doesn't show as a critical fault. I'd suggest you try this first before doing anything else.
Alan S
Marlon65
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Post by Marlon65 »

The compressor of my ZX 1.4 manual '95 model still works well. Since our car are almost the same, I try my best to share my opinion. I think the mechanic who tried to add gas was trying to rip you off or just didn't know what he was doing. Because if the A/C is working when the compressor is engaged, then there is nothing wrong with the gas pressure.
Three years ago I had a similar problem. It would work ok if I tap the dashboard opposite the driver. I finally checked it after the tapping didn't work anymore (after a few months). Under the dashboard opposite the driver is a small plastic box (1"x1"x3"). That piece of box has a relay and small circuit board of the same size. I later found out that something was loose. I fixed it by soldering it myself.
Another way of checking is by disconnecting the power source of the compressor. To check if the A/C is working, supply a different power source to the compressor, say get a 12V source directly from the battery. If the compressor engages and the car becomes cold, then everthing is ok except for some electrical problem mentioned above.
Hope to hear from you again.
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oscarloco
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Post by oscarloco »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by alans</i>

Oscar,
Has the guy who has checked the system also checked the head pressure or only the suction?
<b>Yes, he checked both sides.</b>
This sounds like too much pressure build up on the high side of the system and this can be caused through several things.
Overcharged with gas, air in the system, faulty HP cut out switch or a receiver dryer overdue for replacement.
Other causes can be worn brushes in the condensor fans; I got caught with this one on my '94 Xantia where one fan had worn out the brushes so after a while, the one fan cut out but the other kept going and I only found out about it by accident because the noise indicated both were operating.
<b>Both fans are operating. I had one fail a few years ago and had some overheating problems. Now I have none. </b>
Another and simple thing to check, is that there hasn't been a build up of dirt and leaves between the radiator and the condensor. This can be checked by slackening the radiator and blasting an air hose or preferrably a Karcher or Gerni down between them to blow the muck out. If there's not a good free flow of air through these two cors, this can cause the head pressure to go abnormally high and create problems when the system tries to bring it down using the fans. When driving, with a combination of fans and air passing through them, it doesn't show as a critical fault. I'd suggest you try this first before doing anything else.
<b>I will try this. They guy that charged the system told me that the condenser was dirty and that it needed cleaning. I cleaned it but didn't use compressed air, I will try that</b>
Alan S
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Thanks.
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oscarloco
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Post by oscarloco »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Marlon65</i>

The compressor of my ZX 1.4 manual '95 model still works well. Since our car are almost the same, I try my best to share my opinion. I think the mechanic who tried to add gas was trying to rip you off or just didn't know what he was doing. Because if the A/C is working when the compressor is engaged, then there is nothing wrong with the gas pressure.
<b>He told me that gas was a little low and if I wanted recharged, so thinking that It might solve the problem agreed to it.</b>
Three years ago I had a similar problem. It would work ok if I tap the dashboard opposite the driver. I finally checked it after the tapping didn't work anymore (after a few months). Under the dashboard opposite the driver is a small plastic box (1"x1"x3"). That piece of box has a relay and small circuit board of the same size. I later found out that something was loose. I fixed it by soldering it myself.
<b>Yes, I found some info about that in the aircon forum, apparently the relay controls some large amounts of current and the base can "unsolder" due to a bad soldering.</b>
Another way of checking is by disconnecting the power source of the compressor. To check if the A/C is working, supply a different power source to the compressor, say get a 12V source directly from the battery. If the compressor engages and the car becomes cold, then everthing is ok except for some electrical problem mentioned above.
<b>I'm expecting my Hanes BOL to have some reference and try that</b>
Hope to hear from you again.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Thank you.
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fastandfurryous
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Post by fastandfurryous »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by splat</i>

You've no right to expect an 11 year old Citroen aircon system to work!
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Why not? The 21 year old aircon system in the CX I've just got works fine.
Marlon65
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Post by Marlon65 »

If you want to check it yourself, or if you have the interest, here's what you need to do to check if the relay is working or not. The relay actually is just like a simple switch ON/OFF. Mainly there will be 2 wires (3rd wire maybe there). But mainly the #1 wire will be supplying the 12V. And #2 wire will have 12V if the relay is able to switch ON successfully.
Here's what you need: a half meter wire, a 12-volt bulb, and a needle pin. Connect the wire to a ground, and the other end to the bulb. Connect the + or - of the bulb to the pin.
With the pin punctured to the #1 wire, the bulb should light with the engine ON & A/C ON. Connecting the pin to #2 wire, the bulb should not light with A/C ON and compressor not engaged. Unless the compressor is engaged and working, then the bulb should light up in #2 wire.
Once you are sure it's the relay, remove it from the car and disassemble. Check the base solder of the main power lines, you should find the loose connection there. Good luck.
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