Climate Control Blowing Hot only !

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ianio
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Climate Control Blowing Hot only !

Post by ianio »

well it took the hot weather to realise that the car is blowing only hot air. :oops:

when the dual climate is set to auto and low temps, it blows like the wind but is hot air. when its set to high temp (to match the current ambient temp), the blower slows right down.

that suggest to me that the car knows it needs to provide cold air to the cabin , but the blower unit is stuck on heated air for the intake.

so im guessing there is a flap or something which switches heated air and a/c air?

for background the car is relatively new to me but i suspect would benefit from a re-gassing of the ac system. i just need to resolve this first to check.
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GiveMeABreak
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Re: Climate Control Blowing Hot only !

Post by GiveMeABreak »

The reason it is blowing fast at low temp setting is because it is trying to reach the lower temperature unsuccessfully as your A/C is obviously not working. It will obviously slow down at hotter temperature settings as no cooling is required and the heat is supplied from the engine.

It won't be anything to do with recycled air, because when this is selected it switched the A/C on - and as we know that isn't working.

You either have a leak in the A/C circuit or a chipped condenser or faulty compressor. When the refrigerant is low the compressor is automatically switched off to avoid damage. I suggest you get a specialist to pressure test the system with a dye and take it from there.
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ianio
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Re: Climate Control Blowing Hot only !

Post by ianio »

thanks for that. i agree. the car is trying to cool the cabin so at least the temp sensor is working.

however the air is heated. not just "not cold" its actually hot air being sent to cool the cabin. thats why im thinking a flap or something perhaps/
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xantia_v6
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Re: Climate Control Blowing Hot only !

Post by xantia_v6 »

Look under the bonnet and identify the aluminium pipe that runs from the firewall to the A/C compressor (larger diameter than the other A/Cpipes). After the engine has been running a minute or two, this pipe should be very cold (~8°) to touch. If it is not cold, then you have a problem with the refrigeration system.
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GiveMeABreak
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Re: Climate Control Blowing Hot only !

Post by GiveMeABreak »

There's no no internal physical temperature sensor on these :wink:

The passenger compartment temperature makes it possible, with the reference value displayed, to determine the temperature adjustment necessary to heat or cool the passenger compartment to the required value.

The passenger compartment temperature is calculated from the following elements:
  • External temperature sensor
  • Sun sensor
  • Air flow and distribution
The calculation depends on several parameters stored when the vehicle stopped, such as:
  • Exterior temperature
  • Calculated passenger compartment temperature
  • Day, date, time, second (this information makes it possible to calculate for how long the vehicle has been stationary)
On this vehicle, the passenger compartment temperature is not measured but calculated from a temperature assessment (Result of the sum of the power added and removed). This assessment is made for each zone.

What you need to do is with the engine running, lift the bonnet and ensure that the climate control is on AUTO, then go and check to see if the engine radiator fan is running. If it's not (with A/C on it will always operate on slow speed), then you'll likely find that the A/C compressor is also not engaged. That means the refrigerant is too low and that's why it's shut off.

With out this you will be getting temperature from the outside coming in so may feel warmer and also heated by the engine slightly and therefore without any cooling effect.

If the A/C compressor is working, then you may have a low refrigerant level which is enough for the compressor to engage, but not enough to provide a significant cooling effect. You may also have an air distribution or air mixing reduction motor not working, or indeed a blocked heater matrix that may be reducing the cooling effect.

Either way, the best place to start is having the A/C system checked and tested first. There are mobile companies that will come out and do this for £80 ish.
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ianio
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Re: Climate Control Blowing Hot only !

Post by ianio »

awesome advice. thank you.

i also noted the air mixing reduction motor as a plausible issue. looks like a true pain to fix.

I will post an update for future reference.
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Re: Climate Control Blowing Hot only !

Post by GiveMeABreak »

The motors are generally very reliable on this model and I've not yet heard of one failing on the X7.
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frer8833
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Re: Climate Control Blowing Hot only !

Post by frer8833 »

GiveMeABreak wrote: 25 Jun 2024, 18:17 The reason it is blowing fast at low temp setting is because it is trying to reach the lower temperature unsuccessfully as your A/C is obviously not working. It will obviously slow down at hotter temperature settings as no cooling is required and the heat is supplied from the engine.

It won't be anything to do with recycled air, because when this is selected it switched the A/C on - and as we know that isn't working.

You either have a leak in the A/C circuit or a chipped condenser or faulty compressor. When the refrigerant is low the compressor is automatically switched off to avoid damage. I suggest you get a specialist to pressure test the system with a dye and take it from there.
Hi,

Engine radiator fan is not working, except after driving 400km then it works for 10 min, and AC doesn't cool down because it needs the radiator fan to work first. I was at a mechanic and he told me without checking with computer that the radiator fan was broken so I went and bought it, then another guy who checked the car with computer said to the mechanic that the relay/resistor (it's a resistor according to the part's name) was broken (too?). I asked the mechanic a little later if the fan or the resistor is broken, he said "both are burned". I wonder if it is likely that both are broken or if it is much more likely that one of them is broken? I checked earlier with obd2 scanner the fault codes, it is open or short circuit in the wire to the radiator fan and I even told that to the mechanic. Maybe the fan-wire is loose, melted or corroded?
Last edited by frer8833 on 01 Jul 2024, 11:40, edited 5 times in total.
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GiveMeABreak
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Re: Climate Control Blowing Hot only !

Post by GiveMeABreak »

I can't advise you of which way round it is - whether the engine ECU commands the Fan to come on when the A/C is engaged or whether it is the A/C / Climate ECU or the BSI, but it has to come on to help cool the condenser.

But I can't see anywhere in your replies that you have checked what Xantia _V6 suggested, or that you have had the A/C system checked. Your radiator sounds like it may well need new relays or a fan assembly, but that is likely to be in addition to the A/C system checks which you should also undertake.
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Re: Climate Control Blowing Hot only !

Post by xantia_v6 »

If the radiator fan comes on after driving, then the fan motor is probably OK. There could still be a problem with the fan relay(s) or resistor (depending on the configuration of your model). Replacing parts without a diagnosis of fault codes and live data can get expensive.
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Re: Climate Control Blowing Hot only !

Post by ozvtr »

frer8833 wrote: 29 Jun 2024, 16:15 Engine radiator fan is not working, except after driving 400km then it works for 10 min
...Then the fan IS working!
frer8833 wrote: 29 Jun 2024, 16:15 and AC doesn't cool down because it needs the radiator fan to work first.
The fan IS working.

The radiator fan is ONLY driven by the engine ECU. By the way the engine ECU also controls the A/C compressor (this will become important in a minute). The climate control ECU requests the engine ECU to run the fan (and compressor) to cool the condenser. If the fan is working but it doesn't come on when you turn the climate control to the appropriate setting...then it's the engine ECU that is not turning the fan on (or the compressor). Why? The engine ECU monitors the refrigerant pressures in the A/C system (and a few other things). If those pressures get too high or too low it wont run the compressor or fan.
In some cars LEXIA will report the refrigerant pressures and in some it wont! Don't ask me why only some...I'm not a PSA engineer (thank goodness). HOWEVER, LEXIA will tell you if the engine ECU will allow the fan and compressor to run. How helpful is that? In case you didn't figure it out, I'm being sarcastic...it's not helpful, it doesn't tell you WHY.
OK...yes...if there is a fault in the cooling fan circuit, that will also stop the engine ECU from running the A/C. BUT the fan runs, so the fan circuit seems to be OK.
You said there was an OBDII fault to do with the fan circuit. Can you elaborate on that? That's possibly the fault...but...
Stop "prevaricating about the bush" (as Wallace would say) and put service gauges on the refrigerant lines and find out what the pressures are!
Of all the A/C failures, 99% are because of refrigerant loss! So that would be the first place I would start.
frer8833
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Re: Climate Control Blowing Hot only !

Post by frer8833 »

Also the ECO start/stop only flashes but doesn't work but after that long 400km drive (and it happened after another long drive as well that fan and ECO was on for 5min) both the fan (only at High speed which indicates maybe resistor fault) and the green ECO diode stayed on when idling for 10 min. For Stop/Start an AGM or EFB battery is recommended which the current one probably is not. Maybe the long drive recharged the battery sufficiently for activating stop/start. But why did tĥe fan and ECO turn on simultaneously, is ECO and the fan dependent on each other or is the battery too weak to turn on the fan but it is enough for everything else (except the ECO and perhaps the AC too)? Sometimes electric windows doesn't work either when key is in ON position because of Economy Mode which requires me to start the engine to be able to use the electric windows. This Economy mode happens sometimes. Maybe BSI (BCM) needs a reset?

Besides the tip that it can be low AC refrigerant, I wonder if the fan or AC and ECO is dependent on a strong and full car battery? I dont hear any engagement of AC clutch when pressing AC button, does it engage only if the radiator fan is already working and does it sound like when fuel cap is opened? BTW the first mechanic turned up interior blower to highest level and set temp to Low and Ac button was On but the radiator fan still didnt turn. I wonder why he didnt just check as you suggested the pressure of the AC refrigerant? What is the cost of a mechanic putting service gauges on the lines to check refrigerant pressure? The fan is easy to turn manually which indicates it is ok.

But if low AC refrigerant level is the problem why does the Service diode on the dash come on within 5 min of starting the car? This Service light is caused by the radiator fan not turning at neither High or Low speed according KingBole obd2 scanner (like it is checked for functionality) but shouldnt it be able to turn in this case regardless of refrigerant level? I mean if the car is idling for 12 min shouldn't the radiator fan start working even if AC is off?

I guess the radiator fan works only in High speed mode because I heard a high rpm fan noise after 400km drive so maybe there is a fault with the resistors speed regulation but maybe it is not a fault with the resistor because it should happen much more often that the fan comes on? So maybe both resistor, AC refrigerant level (no AC clutch sound) and battery are bad? If the resistor is corroded that increases the voltage needed from the battery to push electricity through the resistor so if the battery is weak because it is not a proper start/stop battery then maybe the battery is part of the problem?
Last edited by frer8833 on 02 Jul 2024, 19:37, edited 1 time in total.
ozvtr
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Re: Climate Control Blowing Hot only !

Post by ozvtr »

First up, it is possible that the stop start ECU is stuffing things up, if it's not working properly! But I'm not an expert on the stop start system, so I cant comment on that, either way...sorry. The only thing that I might say is that when the car is running, that the stop-start shouldn't effect anything.
frer8833 wrote: 01 Jul 2024, 09:27 I wonder why he didnt just check as you suggested the pressure of the AC refrigerant? What is the cost of a mechanic putting service gauges on the lines to check refrigerant pressure?
How much do you think someone would charge to: open the bonnet (and prop it up), remove the service valve caps, install the service gauge connectors, read the pressure, disconnect the gauges, re-install the caps and close the bonnet? You don't even need the run the engine!! The static pressure will tell you all that you need to know.
frer8833 wrote: 01 Jul 2024, 09:27 But if low AC refrigerant level is the problem why does the Service diode on the dash come on within 5 min of starting the car? This Service light is caused by the radiator fan not turning at neither High or Low speed according KingBole obd2 scanner (like it is checked for functionality) but shouldnt it be able to turn in this case regardless of refrigerant level? I mean if the car is idling for 12 min shouldn't the radiator fan start working even if AC is off?

I guess the radiator fan works only in High speed mode because I heard a high rpm fan noise after 400km drive so maybe there is a fault with the resistors speed regulation but maybe it is not a fault with the resistor because it should happen much more often that the fan comes on? So maybe both resistor, AC refrigerant level (no AC clutch sound) and battery are bad?
OK. Lets take things at face value.
A lot of people think that the cooling fan does a lot of work...it doesn't. Well not on a serviceable cooling system! On a "cool" day it might take 20-30 minutes for the fan to kick in, while the car is idling, and only idling! Of course the give away is the engine coolant temperature rising but the fan doesn't cut in. Does the coolant temp change by more than 5-10 degrees??? If yes, you have a problem. If no, you don't. In a typical engine on a typical day with a serviceable cooling system the coolant outlet temperature is about 90'C (when "warmed up"). The radiator fan typically cuts in between 95 and 100'C (give or take a few degrees). Look at the coolant outlet (engine) temperature...not the fan! If it's "over heating"...worry. Otherwise...don't!

YES! On the surface it is possibly the low speed fan controller that is not working. Clues: "Check engine light" comes on and OBDII says "cooling fan fault". Fan only seems to work on full speed. Have not seen the fan run at low speed.
If the engine ECU is detecting a cooling fan fault it will stop the A/C system from working.

Now the practicality:
Getting someone to check the refrigerant pressure is do-able. Might cost something, but do-able. Just to be a party pooper, you might have two faults. So even low refrigerant might not be all your problems!
The fan circuit: unless you can find someone on this forum who has intimate knowledge of YOUR model of car (I don't), you will need more information. In the least, a circuit diagram, a multimeter and the knowledge to use both of them.
To go down the "cooling fan controller faulty" path you will need to supply your VIN and ask Marc very nicely if he can supply a circuit diagram.

If you want to just fire the parts cannon at the problem, you could replace the resistor and relay pack on the radiator shroud. That's the "usual suspect". If that's what the cooling fan uses...I don't know what it uses. There are several ways PSA control the radiator fan(s). Hmm, a circuit diagram might tell me.

I hope I'm not sounding like a smart-@$$, that's not my intention. Just to get to the problem the fastest practical way.
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Re: Climate Control Blowing Hot only !

Post by Armidillo »

ianio wrote: 25 Jun 2024, 17:39 well it took the hot weather to realise that the car is blowing only hot air. :oops:

when the dual climate is set to auto and low temps, it blows like the wind but is hot air. when its set to high temp (to match the current ambient temp), the blower slows right down.

that suggest to me that the car knows it needs to provide cold air to the cabin , but the blower unit is stuck on heated air for the intake.

so im guessing there is a flap or something which switches heated air and a/c air?

for background the car is relatively new to me but i suspect would benefit from a re-gassing of the ac system. i just need to resolve this first to check.
Sorry to be so late coming in on this, and hope I'm not repeating something you already know...

My (29 yr old) Pug 605 loses A/C gas, to the point where the compressor won't run. Despite it's age, it's a true "climate control" system, with it's own ECU. In that situation, I have found that the climate control system will blow cooler air if I turn the air con button to the "off" position. Now I have not consulted manuals or wiring diagrams on this matter - it is simply my own deduction based on a real-world observation.

This suggests to me that the A/C ECU "thinks" that the air con compressor is still supplying properly cold air and that it mixes some hot - perhaps to prevent icing. If your A/C system does the same thing (actually blows cooler air with A/C button off) then I think you can assume that the ECU and flaps are working, and that you can focus on why the A/C doesn't work. To test the flaps, you can also of course try selecting "Feet" or "Demist" as a change from Face.
GolfMk1Vr6
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Re: Climate Control Blowing Hot only !

Post by GolfMk1Vr6 »

Replace the pressure control valve from the compressor, i solved my issue this way.