If it's got a receiver, charge weight is quite uncritical.
I'd charge to pressure of the low and hi side. Start off with a "drop charge" of 750 gms of R134a and monitor low side and centre vent temperature.
And trim the charge accordingly.
Citroen CX Air Cond Options
- Thread starter Chatty
- Start date
If it's got a receiver, charge weight is quite uncritical.
I'd charge to pressure of the low and hi side. Start off with a "drop charge" of 750 gms of R134a and monitor low side and centre vent temperature.
And trim the charge accordingly.
hi guys,
with summer in full swing, and the need to run errands with the cx, it's become VERY apparent that any amount of air conditioning would be better than none. at the moment, however, i'm not understanding the thermostat dial on the centre console. the clutch on the compressor only seems to be actuating with the dial turned all the way clockwise. isn't this supposed to trigger a recirc motor ?
the relay for the compressor clutch and receiver dryer is connected to one prong (red wire) of a plastic connector with two female lugs coming out of the loom near the heater box - is this correct ? or i notice a seemingly matching male end with nothing plugged into it (right hand side of the intake tower) - is it supposed to plug into that ?
i'm clearly very very confused. sorry for the super vague explanations, the wiring in my car is a mess of disconnected plugs and dodgy bodged repairs. i'm away from the cx right now but when i get home in a few days i can send pictures.
thanks
Max.
with summer in full swing, and the need to run errands with the cx, it's become VERY apparent that any amount of air conditioning would be better than none. at the moment, however, i'm not understanding the thermostat dial on the centre console. the clutch on the compressor only seems to be actuating with the dial turned all the way clockwise. isn't this supposed to trigger a recirc motor ?
the relay for the compressor clutch and receiver dryer is connected to one prong (red wire) of a plastic connector with two female lugs coming out of the loom near the heater box - is this correct ? or i notice a seemingly matching male end with nothing plugged into it (right hand side of the intake tower) - is it supposed to plug into that ?
i'm clearly very very confused. sorry for the super vague explanations, the wiring in my car is a mess of disconnected plugs and dodgy bodged repairs. i'm away from the cx right now but when i get home in a few days i can send pictures.
thanks
Max.
I can only help a little...…
There should be a rocker switch for the recirculation. On my car is it on the drivers side of the consul to the south east of the gear lever, immediately behind the similar rocker switch for the driver's side window motor. My recirculation system flap is currently misbehaving, as they do, although the previous owner changed the system completely.
Yes the rotary switch is a thermostat control. Mind you, you wouldn't want it anything but full on on a CX!
I have no idea what the wiring to that area looks like I'm afraid. See whether Shane replies! He'll probably know.
Last year we had ours overhauled by a good AC specialist here in Perth and it's not bad, with a new compressor and a new condenser. The rear unit works too. So there's a moderate flow of cold air.
Good luck.
There should be a rocker switch for the recirculation. On my car is it on the drivers side of the consul to the south east of the gear lever, immediately behind the similar rocker switch for the driver's side window motor. My recirculation system flap is currently misbehaving, as they do, although the previous owner changed the system completely.
Yes the rotary switch is a thermostat control. Mind you, you wouldn't want it anything but full on on a CX!
I have no idea what the wiring to that area looks like I'm afraid. See whether Shane replies! He'll probably know.
Last year we had ours overhauled by a good AC specialist here in Perth and it's not bad, with a new compressor and a new condenser. The rear unit works too. So there's a moderate flow of cold air.
Good luck.
Hi Max, yes normally the thermostat operates the recirculation when you feel it click around to full AC. The flap motor will probably be burnt out due to age. Replaced it with a new hobby 12v motor plus spare window switch to control. Then buy everything new. Re-pipe the lot. Be prepared to replace to TX valves too; Can be lucky. Sanden SD7H15 heavy duty compressor available online. Otherwise https://ashdown-ingram.com.au/air-conditioning/ has everything you need available over the counter. Put an external tap on your heater to ensure no excess heat (easy to do) & also check the gromet around to choke cable is in place. Surprising how much hot air it allows in if missing. Good luck 
Apart from anything else, I'd definitely endorse the tap on the hot water flow to the heater. I'd never say the CX AC was excellent, but it does provide a reasonable amount of cooling. If you think it is no good, turn it off for ten minutes on a hot day....
So we are looking at a 1979 CX with the Behr heater unit ... There are earlier and later arrangements that are different, the later ones having servo motor controls, while this system is, I'm fairly confident, all cables except for the flap motor in the intake tower.
The intake tower has a small flap motor in it and you have presumably found the leads for it. It's not a stepper, so it simply runs either way until it stalls with the flap either open or closed. It's the same motor as used in a BX, where you can scrounge two of them, but ... the BX puts it inside a case (shell it), the cog is different (swap them - light press fit) and the plug will have a different arrangement. If you can't find one locally and need to replace it, I can send you one. From memory, this is controlled by the fan speed lever and shuts at position 0. It may also shut with the A/C temp knob at max as mentioned above, but I can't recall that detail.
A tap in the heater hose is quite a good idea. A manual tap works, but if you are feeling inventive you can add a vacuum unit with a salvaged vac solenoid to operate it. A micro/reed switch at the cold end of the temperature lever to operate the solenoid works well, but obviously takes a little effort to set up. This works because you only want it shut when you do not want any heat!
The A/C knob in the centre console has a click off position and beyond that you can dial up the temperature you desire. As soon as you turn it on the two cooling fans will go to high speed (handy to remember when it is overheating because the temp sensor behind the radiator has carked it and the fans aren't otherwise running!) The temp control knob supposedly turns the compressor on/off depending on the setting and the measured temperature. It has a long capillary tube and that's what does the measurement. If it's damaged, it won't work. Even if it does work, in a CX it's going to energise the compressor almost all the time because the A/C is usually pathetic. If you make that assumption and the temp knob is actually U/S, you could just as easily replace it with a simple on/off switch as you find in very simple older systems.
The compressor is most likely earthed via the engine, but the second plug, if it leads to the 'other side' of the A/C clutch coil might be missing a pigtail to earth. You obviously need to make a circuit from -ve to +ve via the AC clutch coil and the thermo knob. It's possible someone has added a high/low switch or a thermal fuse and that could explain the extra plugs.
I may not be recalling everything 100% correctly. My CX departed a long time ago now. The wiring diagram should help, although dual air was a local addition so don't expect a diagram including that.
The intake tower has a small flap motor in it and you have presumably found the leads for it. It's not a stepper, so it simply runs either way until it stalls with the flap either open or closed. It's the same motor as used in a BX, where you can scrounge two of them, but ... the BX puts it inside a case (shell it), the cog is different (swap them - light press fit) and the plug will have a different arrangement. If you can't find one locally and need to replace it, I can send you one. From memory, this is controlled by the fan speed lever and shuts at position 0. It may also shut with the A/C temp knob at max as mentioned above, but I can't recall that detail.
A tap in the heater hose is quite a good idea. A manual tap works, but if you are feeling inventive you can add a vacuum unit with a salvaged vac solenoid to operate it. A micro/reed switch at the cold end of the temperature lever to operate the solenoid works well, but obviously takes a little effort to set up. This works because you only want it shut when you do not want any heat!
The A/C knob in the centre console has a click off position and beyond that you can dial up the temperature you desire. As soon as you turn it on the two cooling fans will go to high speed (handy to remember when it is overheating because the temp sensor behind the radiator has carked it and the fans aren't otherwise running!) The temp control knob supposedly turns the compressor on/off depending on the setting and the measured temperature. It has a long capillary tube and that's what does the measurement. If it's damaged, it won't work. Even if it does work, in a CX it's going to energise the compressor almost all the time because the A/C is usually pathetic. If you make that assumption and the temp knob is actually U/S, you could just as easily replace it with a simple on/off switch as you find in very simple older systems.
The compressor is most likely earthed via the engine, but the second plug, if it leads to the 'other side' of the A/C clutch coil might be missing a pigtail to earth. You obviously need to make a circuit from -ve to +ve via the AC clutch coil and the thermo knob. It's possible someone has added a high/low switch or a thermal fuse and that could explain the extra plugs.
I may not be recalling everything 100% correctly. My CX departed a long time ago now. The wiring diagram should help, although dual air was a local addition so don't expect a diagram including that.
I have a tap on the heater pipe, I agree it makes a great difference
OK so I'm pretty sure the connector I have the compressor relay hooked up to is supposed to be for the recirc, as it turns on only when the a/c knob is twisted fully clockwise, or the fan control is set to 0. So y'all think I could just get any old 12v hobby motor and replace the recirc flap motor with that ? Would it perhaps be more reliable if possible to hook up a choke cable to it and operate manually ?
I have located the TX valve and will have a look at replacing it. How can I tell if it's any good?
I have a spare compressor if need be but the previous owner assured me all components of the air con were good it just needed a regas ... by the fact that the compressor clutch relay was hooked up to the LH high beam light prong (god only knows why...) i will take this with a grain of salt.
Thanks so much for all your help
Max.
OK so I'm pretty sure the connector I have the compressor relay hooked up to is supposed to be for the recirc, as it turns on only when the a/c knob is twisted fully clockwise, or the fan control is set to 0. So y'all think I could just get any old 12v hobby motor and replace the recirc flap motor with that ? Would it perhaps be more reliable if possible to hook up a choke cable to it and operate manually ?
I have located the TX valve and will have a look at replacing it. How can I tell if it's any good?
I have a spare compressor if need be but the previous owner assured me all components of the air con were good it just needed a regas ... by the fact that the compressor clutch relay was hooked up to the LH high beam light prong (god only knows why...) i will take this with a grain of salt.
Thanks so much for all your help
Max.
Excuse my ignorance, but how does this capillary tube work, and how would I be able to tell whether it's broken?
The switch seems to work so far as it turns on the fans and operates what i have just figured out was the motor for the recirc flap. Slow learner...
max.
If the air condition is absolutely shithouse ... and only really cools the gearstick. I would suggest it is in perfect working order. The rear unit will do the majority of the cooling.
In very hot weather unless you have pulled everything apart and insulated it (and replaced the deteriated foam in the heater flap ). With perfect working A/C you may find you have 55 degrees from the vents with the A/C off .... and 40degrees from the vents with the A/C on. So the A/C is actually working ok, but the air is just being bought back to ambient temperature. The ONLY way to get a CX comfortable is:
--Working front AND REAR A/C systems. Preferably gassed with bang gas. (the front unit does bugger all as the fans move next to no air ... .There is no fix for this .... No-one has ever solved this even though the car is some 44 years old).
--The front floors, firewall and dash turns into a huge big radiant heater in hot weather in traffic. It MUST be insulated.
--Putting a quaility tint on the windows will make a far better improvement than getting the factory air working ( to the point where in 40degree weather you will travel with the windows up rather than down .... because its so much cooler if the sun is shining on you).
This biggest issue ... by far .... Without a single doubt in the world is that big windscreen. You NEED an athermic windscreen. You could have the inside of the car a balmy 22degrees if you get everything working... Even if it's 42+ degrees outside, you will be lovely and comfortable travelling at night. During the day, sitting under the windscreen ......... You'll fry.
seeya,
Shane L.
In very hot weather unless you have pulled everything apart and insulated it (and replaced the deteriated foam in the heater flap ). With perfect working A/C you may find you have 55 degrees from the vents with the A/C off .... and 40degrees from the vents with the A/C on. So the A/C is actually working ok, but the air is just being bought back to ambient temperature. The ONLY way to get a CX comfortable is:
--Working front AND REAR A/C systems. Preferably gassed with bang gas. (the front unit does bugger all as the fans move next to no air ... .There is no fix for this .... No-one has ever solved this even though the car is some 44 years old).
--The front floors, firewall and dash turns into a huge big radiant heater in hot weather in traffic. It MUST be insulated.
--Putting a quaility tint on the windows will make a far better improvement than getting the factory air working ( to the point where in 40degree weather you will travel with the windows up rather than down .... because its so much cooler if the sun is shining on you).
This biggest issue ... by far .... Without a single doubt in the world is that big windscreen. You NEED an athermic windscreen. You could have the inside of the car a balmy 22degrees if you get everything working... Even if it's 42+ degrees outside, you will be lovely and comfortable travelling at night. During the day, sitting under the windscreen ......... You'll fry.
seeya,
Shane L.
thanks so much for your input. I'll definitely look at getting some good tint (not too dark ... i'm not into the pimp look) and just getting the air con and recirc working ... i'll get it done eventually.
You don't want dark tint (the tint itself being dark with radiate heat otherwise). You want tint that block heat throughput. The tint I used blocked 68% of heat throughput from memory. I would expect in the 10+ years since I did mine, that tint will have improved further.
seeya,
Shane L.
The Nano Carbon Ceramic tints are the best at blocking heat, even with a light tint.
Turning the heater off manually (with a choke cable or by other means) is mandatory.
I know the other Shane may question me on this, but I only have the factory A/C and it works reasonably well. We have just had 3 weeks of over 40C up here in Albury, and it struggled at times, but I never got too hot. But of course that depends on what you are used to and can tolerate. Coming from the Riverina where the temp often reached to 45-48C I don't really feel the heat much.
But the other day I had a friend travel with me out west and he has major medical problems and will dehydrate very easily, and he seemed to think it was not too hot in the car.
Turning the heater off manually (with a choke cable or by other means) is mandatory.
I know the other Shane may question me on this, but I only have the factory A/C and it works reasonably well. We have just had 3 weeks of over 40C up here in Albury, and it struggled at times, but I never got too hot. But of course that depends on what you are used to and can tolerate. Coming from the Riverina where the temp often reached to 45-48C I don't really feel the heat much.
But the other day I had a friend travel with me out west and he has major medical problems and will dehydrate very easily, and he seemed to think it was not too hot in the car.
Out of interest, do you know whether any of these light tints are yet legal for windscreens? The old athermic windscreen business still lurks out there if enough were interested.....
Perth is usually pretty hot, but we've only had three hot days this year, while watching the eastern states bake. Amazing.
Cheers
John
Okie doke, so i'll look at having a nano carbon ceramic tint done first and foremost - i'd better start looking for someone who will do them. thanks for all your help. i'll also have a go at finding a way to operate the recirculation flap since that seems like something that would make a good amount of difference (also just something i want to work for the sake of working)
thanks kindly
Max
thanks kindly
Max
There were discussions way back about the wisdom of insulating the air tower too - black plastic just behind the engine..... Come to think of it, I haven't done that myself....
The ventilation flow through (or the lack thereof) is the biggest issue I suspect. One car in Perth had its bonnet reconstructed (at great expense) to get the air inlet moved forward into a higher air pressure zone. The owner claims good results but I've not been in the car. My lateral thinking, also not implemented, would be to have a fan at the back of the cabin driving the air OUT at the back. All good airflow systems seem to be based on getting the air out, the inlet being a much smaller issue. So, where to put it? I'm going to have to go and have a beer (it's 38 degrees here) and ponder that one. Given the rear AC unit, perhaps a big fan underneath a front seat blowing down and out?
There's another 10 amps of 12V demand......
The ventilation flow through (or the lack thereof) is the biggest issue I suspect. One car in Perth had its bonnet reconstructed (at great expense) to get the air inlet moved forward into a higher air pressure zone. The owner claims good results but I've not been in the car. My lateral thinking, also not implemented, would be to have a fan at the back of the cabin driving the air OUT at the back. All good airflow systems seem to be based on getting the air out, the inlet being a much smaller issue. So, where to put it? I'm going to have to go and have a beer (it's 38 degrees here) and ponder that one. Given the rear AC unit, perhaps a big fan underneath a front seat blowing down and out?
There's another 10 amps of 12V demand......
I don't think getting the air out of the car is the issue with a refrigerated system. You want to re-circulate it if possible. It doesn't work like an evaporative system where you need to keep large flows moving through. Like others have said, you can't change the basic system too much without a large expense. Cooling the gear lever well is as much as you can expect from a standard system. You need to work on keeping it as efficient as possible, by tinting, insulating, Athemic windscreen, SHUTTING OFF the heater totally.
I will be using a very light tint on my windscreen in Europe where it is legal. One fellow I spoke to who tried it here said he ripped it out again because of the bad reflection issues at night. I don't think it has been tackled in Australia.
You can put me down for 2 Athermic screens (maybe 3) if someone is organising something?
You have a point about the recirculation..... My wife wasn't totally convinced about putting a radiator fan underneath the driver's seat either - the only sensible place I could think of for exhausting the air. Time I went and looked at the key flap I think. And I believe in SE Asia they blocked off the air intake altogether. Leaves a bit of room in the engine bay!
We've had a couple of vague attempts to find out who'd buy an athermic screen (I would) but no-one has quite offered to champion it. I'd like to but know better, given other commitments etc.
Cheers