My fans run on full speed as soon as the AC is turned on with both CX and Xantia. I've no idea what was standard but it makes sense to me to have maximum airflow as the AC is on because it is hot mostly.
Citroen CX Air Cond Options
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My fans run on full speed as soon as the AC is turned on with both CX and Xantia. I've no idea what was standard but it makes sense to me to have maximum airflow as the AC is on because it is hot mostly.
It's so that the draw on the battery is lowered when the car is at speed which maybe a mute point as the c-matic overrides the fan anyway (oil temp sensor) so more than likely it will always be on high now I think of it.
Live and learn. I didn't know there was an oil temp sensor linked to the fans in the CX. I guess I need to own it for 20 years not 10 to sort these little details out! :0 Thanks for the info.
Moot not mute too, but that's non-froggie pedantry.
Live and learn. I didn't know there was an oil temp sensor linked to the fans in the CX. I guess I need to own it for 20 years not 10 to sort these little details out! :0 Thanks for the info.
Moot not mute too, but that's non-froggie pedantry.
You're right on both counts. More crosswords for meI'm only going off the wiring diagram for a C-matic with A/C and the oil temp sensor seems linked to one relay? The light would have to occur to complete the circuit? That would be rare & possibly too late! Currently I have to switch off the A/c to change gear when in slow traffic. Just when cool air is needed most. I also have a temp gauge to add so will need to work out how to keep the red warning light working.
Live and learn. I didn't know there was an oil temp sensor linked to the fans in the CX. I guess I need to own it for 20 years not 10 to sort these little details out! :0 Thanks for the info.
Moot not mute too, but that's non-froggie pedantry.
You're right on both counts. More crosswords for me�� I'm only going off the wiring diagram for a C-matic with A/C and the oil temp sensor seems linked to one relay? The light would have to occur to complete the circuit? That would be rare & possibly too late! Currently I have to switch off the A/c to change gear when in slow traffic. Just when cool air is needed most. I also have a temp gauge to add so will need to work out how to keep the red warning light working.
Sounds like not enough volts left when the fans are running doesn't it. I have a Stewart-Warner voltmeter fitted and it has a proper galvanometer movement, so responds instantly to changes, unlike most others that are bimetallic strips or something that move very slowly. Good investment - they appear on ebay from time to time - as you really can see what is happening.
Mine drops nearly a volt when the AC is switched on, despite the electrical system being in fairly good shape with a newish 120 amp Bosch alternator. Not any gear change trouble.
Cheers
The wiring in the Prestige starts the fans on low speed as soon as the air-conditioning is turned on. But my 1978 C-matic did not. You can easily set up a trigger for low speed form the feed to air-conditioning compressor. It is kind of running in parallel with the thermal switch that hangs down behind the radiator
If you are having problems changing gear with the AC on, you either have a wiring issue or your alternator is not up to the job. I would first be measuring battery voltage with engine idling, AC on, lights on. If it is up to speck, the issue is wiring and as I suggested put a relay in the final feed to the C-matic solenoid.
If you are having problems changing gear with the AC on, you either have a wiring issue or your alternator is not up to the job. I would first be measuring battery voltage with engine idling, AC on, lights on. If it is up to speck, the issue is wiring and as I suggested put a relay in the final feed to the C-matic solenoid.
I found when I had a cx that the heater tap was jammed. I removed it and dismantled it. That was an interesting exercise because I found that internally it had broken, so that no matter what position you set the control, the water would always flow through. So, removing the tap, or replacing it might make a HUGE difference. The other poor design was that the fan heater/cooler blower motor wasn't really powerful enough. I swapped it for one from a Japanese car at the wreckers and ended up with better air flow, but still not really good enough. I came to the conclusion that the air intake was too small or restricted to get enough air flow.
Heater tap
Certainly the heater tap working effectively and completely is a key component in getting the A/C working adequately. I have a manual tap operated remotely by a cable routed to the cabin console. It works very well, but either needs cleaning or adjusting as it turns on properly from the cabin, but does not turn off completely. I need to open the bonnet and push it the last fraction to get it off completely. If it is not off completely you may as well leave the A/C off. So it makes a huge difference.
I have done what Shane (the other one!) did, and completely insulated the cabin, boot and under bonnet area. I am not sure if i ended up sealing off the boot from the cabin or not, but I think not (the holes in the metal barrier).Then I got the best tinting job money could buy on side and rear windows (new generation tinting, I can fish out the details if anyone in interested?) I was planning on gassing it with the alternative gas Shane uses (can't remember the name just now) but the fellow gassed it with standard gas so I decided to see how it would go. I am pretty happy with how the standard system operates, even up to temperatures above 40C, and it was actually cold.
Yes, it is a CX, it has a standard A/C running modern gas, and I am not suffering sun stroke at the moment (as it is -12C where I am at the moment), and other people seem to think I am reasonably sane, and on my reckoning it was cold enough! I have not had the opportunity to test it at 48C or higher (as we used to experience in the Riverina (Urana), but will certainly take the first chance to do this in the future. On occasion I actually had to turn the fan down to middle or lower settings - can you believe that! From memory, the condenser fans both operate from the get go, but I wouldn't stake my life on it, because the other things had higher priority at the time.
So I would pay attention to details like the heater tap, insulation, and a good tinting job, and perhaps sealing the cabin, before spending too much effort or money on other alternatives.
Certainly the heater tap working effectively and completely is a key component in getting the A/C working adequately. I have a manual tap operated remotely by a cable routed to the cabin console. It works very well, but either needs cleaning or adjusting as it turns on properly from the cabin, but does not turn off completely. I need to open the bonnet and push it the last fraction to get it off completely. If it is not off completely you may as well leave the A/C off. So it makes a huge difference.
I have done what Shane (the other one!) did, and completely insulated the cabin, boot and under bonnet area. I am not sure if i ended up sealing off the boot from the cabin or not, but I think not (the holes in the metal barrier).Then I got the best tinting job money could buy on side and rear windows (new generation tinting, I can fish out the details if anyone in interested?) I was planning on gassing it with the alternative gas Shane uses (can't remember the name just now) but the fellow gassed it with standard gas so I decided to see how it would go. I am pretty happy with how the standard system operates, even up to temperatures above 40C, and it was actually cold.
Yes, it is a CX, it has a standard A/C running modern gas, and I am not suffering sun stroke at the moment (as it is -12C where I am at the moment), and other people seem to think I am reasonably sane, and on my reckoning it was cold enough! I have not had the opportunity to test it at 48C or higher (as we used to experience in the Riverina (Urana), but will certainly take the first chance to do this in the future. On occasion I actually had to turn the fan down to middle or lower settings - can you believe that!
From memory, the condenser fans both operate from the get go, but I wouldn't stake my life on it, because the other things had higher priority at the time. So I would pay attention to details like the heater tap, insulation, and a good tinting job, and perhaps sealing the cabin, before spending too much effort or money on other alternatives.
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I've now moved on to solving the airflow in the CX2200 and reinstating the air conditioning. It has the rare second tacked on evaporator in front of the gearshift. I know of only one other that RobT saw at a wreckers a few years ago. Has anyone had any experience with a working one?
Problems: 1) the flap that directs air to the fixed face grill OR screen demist has a broken plastic shaft (flimsy) 2) a dustpan full of grime was blocking the unit internally 3) the second evap was impeding airflow to eye ball vents.
I decided to compare this earlier '76 unit to the one from my '78 wreck and the earlier one is of far better quality. Proper rubber seals molded on metal flaps, no crumbling clued foam on sharp surfaces. Even the '76 evaporator is a thicker better-looking unit than the '78, which makes it surprising that they required a second one.
The early unit must be a Citroën in house item? (No branding) It is very well put together and the electrical loom has better insulation and placement. There are definitely less parts in the later Behr branded unit though (accountants?) and better placed face vents. The flow through on the early one looks less interrupted without the heater blend door.
The problem with the '76 unit is that face eyes ball vents feed from where the foot vents would be on the Behr unit and that where the second evaporator was added (three right angles turns) . This really would have slowed down the flow.
The plan is to combine the best of both and add in a serviceable filter.
Problems: 1) the flap that directs air to the fixed face grill OR screen demist has a broken plastic shaft (flimsy) 2) a dustpan full of grime was blocking the unit internally 3) the second evap was impeding airflow to eye ball vents.
I decided to compare this earlier '76 unit to the one from my '78 wreck and the earlier one is of far better quality. Proper rubber seals molded on metal flaps, no crumbling clued foam on sharp surfaces. Even the '76 evaporator is a thicker better-looking unit than the '78, which makes it surprising that they required a second one.
The early unit must be a Citroën in house item? (No branding) It is very well put together and the electrical loom has better insulation and placement. There are definitely less parts in the later Behr branded unit though (accountants?) and better placed face vents. The flow through on the early one looks less interrupted without the heater blend door.
The problem with the '76 unit is that face eyes ball vents feed from where the foot vents would be on the Behr unit and that where the second evaporator was added (three right angles turns) . This really would have slowed down the flow.The plan is to combine the best of both and add in a serviceable filter.
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The vent temperature can get quite low with the fans running full bore... so it's not the cooling ability of the evaporator that's the issue, it's the amount of air the fan can move
sadly I can't see the extra evaporator helping unless it's has a secondary fan!
Yes the other problem is the convoluted tower ducting used for both fresh or recirculating air. The fans themselves are very powerful. The little evaporator could be mounted in the glove box out of sight with another small fan just feeding the outer face vents very easily and the dash would look unchanged. I'll get each evaporator flushed and pressure tested to see what's viable next.The vent temperature can get quite low with the fans running full bore... so it's not the cooling ability of the evaporator that's the issue, it's the amount of air the fan can move
sadly I can't see the extra evaporator helping unless it's has a secondary fan!
When I went to recharge the Air-conditioning I found a guy who will fill with Hychill. When we were regassing it, noted some small bubbles appearing between the front plate and body of the compressor. We have found the leak. That was about 6 months ago and the system worked surprising well even if the gas level was slowly falling, but time to fix properly. Sanden do a new compressor that is a drop in replacement for the SD508 in the car, but Jason suggested why don't you get the original overhauled and he knows a guy that does it. His reasoning was, longer guarantee with a guy you know and probably cheaper. I liked the idea on the basis of not throwing anything away if it still works or can be fixed. Job was completed a few weeks ago, cost $400 to overhaul the compressor and then degassed with R134A. First impressions are good, you can't hear the compressor anymore and air coming out the vents is cold.
Still it needed a good test. Yesterday was predicted to hit 41C in Sydney, so the perfect day to take the CX to work and test the A/C. Parked the car where I thought it would be in shade in the afternoon, but when I returned in the afternoon to drive home at was dappled shade. Weatherzone listed the temp at Sydney airport, not far from work at 42.4C. Get all fans to max and the thermostat right around to trigger recirculation. After about 3km the interior is liveable and after about 10km comfortable. Problem is we are travelling south and the sun is pouring in on the drivers side. When we turn to the west things improve although an Aethermic windscreen would have helped. I think a CX Prestige has more window area on the side than the front. Traffic was heavy which didn't help. Compared to the Prius which did the same job the day before in 37C heat. The two took the same distance to get the inside liveable, but it was able to pull the temp down a bit more. It has the advantage of much less traffic on its drive, less volume to cool and compressor speed independent of vehicle/ engine speed.
Therefore I would say the CX passed its test with flying colours
Still it needed a good test. Yesterday was predicted to hit 41C in Sydney, so the perfect day to take the CX to work and test the A/C. Parked the car where I thought it would be in shade in the afternoon, but when I returned in the afternoon to drive home at was dappled shade. Weatherzone listed the temp at Sydney airport, not far from work at 42.4C. Get all fans to max and the thermostat right around to trigger recirculation. After about 3km the interior is liveable and after about 10km comfortable. Problem is we are travelling south and the sun is pouring in on the drivers side. When we turn to the west things improve although an Aethermic windscreen would have helped. I think a CX Prestige has more window area on the side than the front. Traffic was heavy which didn't help. Compared to the Prius which did the same job the day before in 37C heat. The two took the same distance to get the inside liveable, but it was able to pull the temp down a bit more. It has the advantage of much less traffic on its drive, less volume to cool and compressor speed independent of vehicle/ engine speed.
Therefore I would say the CX passed its test with flying colours
Drove my cx in the heat yesterday and found the aircon adequate and comfortable,it is a twin air system. The only issue I have with it,and one needs to remember,it is a 30 year old system,is that the side vents barely produce anything,Andy.
Side vents are an issue. RobT has sold his CX now yet his party trick was that he installed ducted fans each side (from remote controlled model jets) with a speed control. Strong enough to blow a sports cap off your head!
The downsides: noise was huge, air was rushing too fast over the evaporator to cool any better and they wont last if used continuously. Great fun though. His car was probably the best CX system I've experienced and it ws due to Hychill working best in r12 systems. Safety concerns is why I went back to r134a yet it is not as effective.
A question for the technical minded: Ive noticed the return line t-piece really freezes over. It seems a waste to go directly back into the compressor to be pressurised and heated again so soon. Could a secondary evaporator less a Tx valve be added to the tower to sort of pre-chill incoming air? Or even to a secondary condenser be placed in front of the main to help cool incoming frontal ambient air or instead some type of heat exchanger to bring down the low pressure side temp for improved efficiency? (ie. wrapped high and low side pipes together?) I've seen that early Maseratis used the return line to cool the fuel and carburettor to reduced evaporation. Knowing it is the changing state of the gas from liquid to gas and the superheat ratio that make the systems work; would it turn into a gas (low side) before reaching the compressor and be a problem?
Wrap in some self amalgamating cork tape or insulate it with some 10mm armorflex and tape it up.
Insulflex Cork Tape - Actrol
A little local freeze is nothing to be concerned about, simply cold refrigerant cooling the fitting and condensing/ freezing the moisture.
If,however the "freeze line" extends to the evaporator tx valve inlet, there could be TX sizing issues or insufficient airflow through the coil to provide sufficient heat load to raise the coil temperature.
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Is the motor you fitted designed to sit stalled indefinitely
Yes, this is still the common practice... Combine it with dodgy little plastic gears and then bury them under the dash so its a full day's job to replace them. I replace the failed one in the Reno 21 with the vacuum pod from a Fuego and a little vacuum switch and relay from a Fuego emission control system - I didnt want to pull the dash out again...
Thanks Rob. Do you mean the evaporator coil? I'm not concerned about the freezing over of the joins just the waste of chilled energy. The bigger the condenser the better the a/c performance, more cooling area the cooler the result, is that correct? Therefore the chilling of the high pressure line? The trouble with a CX is at the lights, idle speed drops, Compressor circulation reduces pressure at the Tx valve. The under bonnet temperature also increases and the high line running under car picks up more road & exhaust heat. It's as though the process goes on hold, or does it mean I need more gas?
Yes indirectly, but the symptoms, ie freezing, are likely to show on the liquid line leading into the TX valve.
Generally yes, because the evaporator gives back the heat collected from the evaporators to the atmosphere. So the better it loses heat the lower the pressure of refrigerant and therefore the lower head pressure of compressor. Thus improving efficiency of the entire cycle.
Probably not. Because aircon refrigerant charge is pretty flexible. The system has a receiver (dryer).The receiver tends to collect liquid refrigerant ready to metered out by the Tx valve, So provided the supply the TX valve is 100 % liquid then charge is OK.
In days gone by, the site glass was used to determine charge - no bubbles =correct charge - the was with R12, however all other refrigerants foam so you can't use this method anymore. If you are getting adequate cooling and sensible hi side and lo side pressures I'd believe these.
Have to say I'm not too sure about your theories about heat loss/ gain in engine refrigeration lines.
Have a read up on basic refrigeration principles. These notes cover the subject fundamentals quite well.
Automotive air conditioning training manual
Is this a dual system Greg?
Mine is working well as an original single system, although the gas (standard) has been slowly leaking out over the year. Since I only drive it a few months of the year when I return home, I am quite pleased with it.
I was amazed when I was home in August to October to do some serious distance in it to find it is returning 5.55 lts./ 100 km. on the freeway. It had an issue with pump timing and fueling, and so I took it to diesel mechanic again, and luckily for me he had a new employee who came form Portugal and had worked on CX diesels in France for many years. He adjusted the fuel setting and re-timed it (simply by ear and nose) and now it is going really good. Heaps of power and so economical. Of course around town it is not so fuel efficient. I did over 5,000 k's in a few weeks while I was home.
Mine is working well as an original single system, although the gas (standard) has been slowly leaking out over the year. Since I only drive it a few months of the year when I return home, I am quite pleased with it.
I was amazed when I was home in August to October to do some serious distance in it to find it is returning 5.55 lts./ 100 km. on the freeway. It had an issue with pump timing and fueling, and so I took it to diesel mechanic again, and luckily for me he had a new employee who came form Portugal and had worked on CX diesels in France for many years. He adjusted the fuel setting and re-timed it (simply by ear and nose) and now it is going really good. Heaps of power and so economical. Of course around town it is not so fuel efficient. I did over 5,000 k's in a few weeks while I was home.