Forgive this stupid Aircon question...
Discussion
How would you normally switch it on? Only Im pretty sure mine doesnt work...
The reason Im not sure is because my heater control box wasnt fitted when I got the car so I have never used the aircon. I have since fixed the hot fan fault and refitted it. So I now hot side fixed with hot air blowing and red and blue lights illuminated. On the cold side the small blue light comes on as well but turning/pushing the dial etc doesnt seem to do anything.
If someone could just tell me how its supposed to work and what I should check through to see what might need sorting. It might just be a re-gas.
Thanks, Adz
The reason Im not sure is because my heater control box wasnt fitted when I got the car so I have never used the aircon. I have since fixed the hot fan fault and refitted it. So I now hot side fixed with hot air blowing and red and blue lights illuminated. On the cold side the small blue light comes on as well but turning/pushing the dial etc doesnt seem to do anything.
If someone could just tell me how its supposed to work and what I should check through to see what might need sorting. It might just be a re-gas.
Thanks, Adz
As you know, pushing the heater knobs in switches the fans on and off, but to engage the aircon you also have to push the button on the lower panel (iirc next to the heated screen button) and a small blue light should illuminate. You should hear a small sound as you do this, dependant on what type of aircon system you have. I know mine makes a slight 'plink' noise (sorry, but you are asking 'me' about technical issues 
) Obviously if you want cold aircon, make sure the hot blower is off and vice versa.
) Obviously if you want cold aircon, make sure the hot blower is off and vice versa.Sounds daft, but have you pressed the AC button next to the heated rear screen button (it will be unmarked if you have an early car)? I didn't even realise mine had aircon for some time, as the blue LED that illuminates next to the AC button is so pathetically dim that you can't see it unless its night time.
Okay thanks chaps, Im pretty sure that if I press in the blue dial, it does NOT kick the fans in. The only way the fans run is if when I press in the red dial. So maybe this the the problem?
I think when I press the little blue button there is a slight plink (nicely put FU). I will look at it again when I get home.
I think when I press the little blue button there is a slight plink (nicely put FU). I will look at it again when I get home.
Bigadz said:
Okay thanks chaps, Im pretty sure that if I press in the blue dial, it does NOT kick the fans in. The only way the fans run is if when I press in the red dial. So maybe this the the problem?
I think when I press the little blue button there is a slight plink (nicely put FU). I will look at it again when I get home.
There are seperate fans for hot and cold - in otherwords pressing the blue dial should kick in a fan (its noisy so its not like you will miss it) When you press the hot dial its a different fan that cuts in, so in your case it looks like something is wrong with the cold fan. However none of that really has anything to do with the aircon, the cold fan will run whether or not the Air Con compressor is running.I think when I press the little blue button there is a slight plink (nicely put FU). I will look at it again when I get home.
Bigadz said:
So my aircon pump/system might be working fine (I can here something click on) its just the cold fans which are causing me the issue.
Thanks, I think I am narrowing it down now, want to get this running before summer.
Is your car a Speed 6 or AJP?Thanks, I think I am narrowing it down now, want to get this running before summer.
If its a Speed 6 the Air Con Compressor (and valves) is located under the airbox just in front of the alternator - so basically impossible to see if its running with the car started! handy! unless you want to run it for a few minutes without the airbox on
Sure the AJP boys will be along in a minute to tell you where to look on the V8's
Bigadz said:
So my aircon pump/system might be working fine (I can here something click on) its just the cold fans which are causing me the issue.
Thanks, I think I am narrowing it down now, want to get this running before summer.
Yes, if you can here the click/tinkle when you turn the aircon on, its working. If there is no cold air coming out the vents when you click on the cold blower its not unknown for the pipe/ducting to come unattached. Might be something as simple as that.Thanks, I think I am narrowing it down now, want to get this running before summer.
Sounds like your compressor is cutting in but you need the cold blow fan working, even if it was you will struggle to tell if the air con is working with these cold outside temperatures as the system will probably not cool the air below 10-15 degrees.
You need warm ambient outside air for the system to chill for you, if the car is in a heated garage don't run it !! no cats = v sleepy
You need warm ambient outside air for the system to chill for you, if the car is in a heated garage don't run it !! no cats = v sleepy
Below are my notes re checking the aircon. They may be of some use if the clutch on the compressor is not engaging.
Diagnosing Why the Air Conditioning Clutch Doesn’t Engage
The pressure switch is on top of the receiver drier bottle.
The drier bottle is in the front of the passenger side wing in front of the wheel.
Accessible by taking the wheel off and removing the rectangular inspection cover (its below the circular cover for access to the headlamp).
The drier is a thermos flask size and shape. Its held in a P clip type fastener that is bolted to the back of the inspection cover.
It is a pain to get at and it will be very rusty because of all the water that comes in through the hole under the front indicator
It has two hoses connected to it and an electrical plug attached at the top. Disconnect the plug and give it a good clean with contact cleaner and spray with WD40 or similar.
WARNING WARNING WARNING
All of the following is from a 98 4.2. TVRs vary so if in any doubt about wires/colours/pins and plugs don't start waving a multimeter around the electrics
Before doing anything pore over the wiring diagrams from the Cerbera CD and make sure you have identified the plugs and control boxes and the connectors.
If you can't match pin numbers and wire colours with the diagrams do not proceed with the testing.
Earth on the heater contol box is a black wire on pin B3 of the connector with fewest wires
12V is pin B1 on the other connector - green wire
When the AC switch is pressed the heater control box puts a request into the ECU for the aircon to be turned on. The request is 12V on a wire via a relay that goes through the thermostat switch and the pressure switch.
If the ECU says yes it pulls another wire to 0V that energises a second relay in the heater control box that puts 12V onto the AC clutch wire out of the control box to the red wire going into the compressor.
Sooo nice and simple and not much to go wrong
Turn it on and test for 12V at the red wire going to the compressor. (I use the oil filler cap as earth) If it’s live there is a problem with the box of tricks on the compressor.
If no 12V at the red wire then here we go.....
When the AC switch is pressed you should hear a click from the first relay in the heater control box.
If the relay has clicked then you should be able to measure 12V on one or both contacts of the thermostat in the driver footwell (need to measure from the contact to a suitable earth). If only one contact has 12V then the thermostat is open and you have found the problem.
If neither are live check there is 12V at pin B2 white/pink wire on the heater control box. If not the box is faulty.
If both contacts are live then the pressure switch is next in the chain.
Check this at the engine harness connector in the passenger footwell. Its probably hidden up above the roll cage next to passengers left knee.
IIRC its pin 19 and a white pink wire. Its right at one end of the plug. Again test to a suitable earth.
If no 12V then the pressure switch is open and its mucky contacts or the pressure is too high or too low.
If there is 12V then it could be an ECU or heater control box fault.
If the ECU is happy then there should be 0V at the heater control box pin A6 which is white/black
and there should be 12V at pin B5 which is white/green. This is the feed to the AC clutch so if this is at 12V and the red wire at the compressor is not there is a break in the wiring somewhere betwixt compressor and control box.
Diagnosing Why the Air Conditioning Clutch Doesn’t Engage
The pressure switch is on top of the receiver drier bottle.
The drier bottle is in the front of the passenger side wing in front of the wheel.
Accessible by taking the wheel off and removing the rectangular inspection cover (its below the circular cover for access to the headlamp).
The drier is a thermos flask size and shape. Its held in a P clip type fastener that is bolted to the back of the inspection cover.
It is a pain to get at and it will be very rusty because of all the water that comes in through the hole under the front indicator
It has two hoses connected to it and an electrical plug attached at the top. Disconnect the plug and give it a good clean with contact cleaner and spray with WD40 or similar.
WARNING WARNING WARNING
All of the following is from a 98 4.2. TVRs vary so if in any doubt about wires/colours/pins and plugs don't start waving a multimeter around the electrics
Before doing anything pore over the wiring diagrams from the Cerbera CD and make sure you have identified the plugs and control boxes and the connectors.
If you can't match pin numbers and wire colours with the diagrams do not proceed with the testing.
Earth on the heater contol box is a black wire on pin B3 of the connector with fewest wires
12V is pin B1 on the other connector - green wire
When the AC switch is pressed the heater control box puts a request into the ECU for the aircon to be turned on. The request is 12V on a wire via a relay that goes through the thermostat switch and the pressure switch.
If the ECU says yes it pulls another wire to 0V that energises a second relay in the heater control box that puts 12V onto the AC clutch wire out of the control box to the red wire going into the compressor.
Sooo nice and simple and not much to go wrong
Turn it on and test for 12V at the red wire going to the compressor. (I use the oil filler cap as earth) If it’s live there is a problem with the box of tricks on the compressor.
If no 12V at the red wire then here we go.....
When the AC switch is pressed you should hear a click from the first relay in the heater control box.
If the relay has clicked then you should be able to measure 12V on one or both contacts of the thermostat in the driver footwell (need to measure from the contact to a suitable earth). If only one contact has 12V then the thermostat is open and you have found the problem.
If neither are live check there is 12V at pin B2 white/pink wire on the heater control box. If not the box is faulty.
If both contacts are live then the pressure switch is next in the chain.
Check this at the engine harness connector in the passenger footwell. Its probably hidden up above the roll cage next to passengers left knee.
IIRC its pin 19 and a white pink wire. Its right at one end of the plug. Again test to a suitable earth.
If no 12V then the pressure switch is open and its mucky contacts or the pressure is too high or too low.
If there is 12V then it could be an ECU or heater control box fault.
If the ECU is happy then there should be 0V at the heater control box pin A6 which is white/black
and there should be 12V at pin B5 which is white/green. This is the feed to the AC clutch so if this is at 12V and the red wire at the compressor is not there is a break in the wiring somewhere betwixt compressor and control box.
You need to check that you have got refrigerant in the system as without it, it will not run. Take off the cap by the compressor and gently press in the schrader valve . You should see quite a bit of pressure come out similar to a tyre pressure. But I stress do it carefully and not looking directly at it. Put a glove on also. If nothing comes out you need a pressure test and recharge.
Good tip SL. I will be checking it as soon as I have sorted out my intermittent door switch.What I do know is.
Blue dial pressed for fans - nothing
Blue led button - goes on and off.
So I will have to work out what's going on from here. Might be a combination but the cold fans are definitely not coming on.
Blue dial pressed for fans - nothing
Blue led button - goes on and off.
So I will have to work out what's going on from here. Might be a combination but the cold fans are definitely not coming on.
Now I am not sure where the aircon compressor is on an AJP but for a Speed6 the easiest thing to do to check the compressor is cutting in for sure is to check the magnetic clutch is engaging. If you can see the compressor (which you can on a Speed 6) then it should be driven by a belt and turning with the engine running. However in front of the compressor pulley is a circular plate, this plate turns when the magnetic clutch is engaged - if its not turning then the clutch isn't engaged and you will have no aircon for certain.
With mine there is a slight drop in revs when the magnetic clutch is engaged and you also can hear it engage but only from outside the car. Inside the 'click' in inaudible
In the link below you can see the circular plate (black) in front of the pulley
http://www.tvrpower.co.uk/store/slug/aircon-comprr...
With mine there is a slight drop in revs when the magnetic clutch is engaged and you also can hear it engage but only from outside the car. Inside the 'click' in inaudible
In the link below you can see the circular plate (black) in front of the pulley
http://www.tvrpower.co.uk/store/slug/aircon-comprr...
Edited by PuffsBack on Wednesday 7th March 12:32
You can easily see the compressor clutch engaging on an AJP v8 Also the cold fan works independently of the air con. Pressing the blue speed dial with the ignition on should turn the fan on - it will be easy to hear. The same as the red one will turn the hot fan on. They are switched and controlled independently.
The air con is switched by the button next to the demist one and is only an on/off affair. When you press that button with the engine running you should hear a click and see the centre part of the clutch at the front of the compressor start spinning with the rest of it. The clutch will not engage if the pressure is too low, but this has no bearing whatsoever on the cold fan running, which will operate regardless of the state of the air con.
The air con is switched by the button next to the demist one and is only an on/off affair. When you press that button with the engine running you should hear a click and see the centre part of the clutch at the front of the compressor start spinning with the rest of it. The clutch will not engage if the pressure is too low, but this has no bearing whatsoever on the cold fan running, which will operate regardless of the state of the air con.
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