Car Air Conditioning Problem

[Click4]

Hi, im quite new to the air conditioning world, and today I came accross a car which would not accept a full liquid charge on the high pressure port.

It is supposed to take 810grams of refrigerant, but it hit 470grams and just stopped charging.

Any ideas?

I have a feeling there is an obstruction of some kind, when I start the car up and switch on the air conditioning it does work, but when i try to add the correct charge it hits a wall.

Would I be correct in the likely suspects being the reciever dryer and / or orifice tube causing some kind of obstruction?

Pressure tested it with nitrogen to 150psi, and it holds its pressure fine, also sprayed the joints where visible and couldnt find any leaks.

Pulled a vacuum, vacuum also held fine for over an hour, but I was struggling to hit anything more than 25 hg-in and get below 2000 microns on my digital guages.

[Luke.G]

Hi,
This is probably because your high side gauge point is the same or if not higher than the bottle pressure......
Flash liquid through the suction to get the correct charge

you can only put so much refrigerant in with just a vacuum.
As you said it works so i highly doubt there's a restriction but it will work better with a full charge.

Thanks,
Luke

[Click4]

Hi, Thanks for the reply

Just a thought, but if I got a heater on the tank.. that would increase the tank pressure and force it through?

I have a tank heater, but yet to use it lol

[install monkey]

run the system and charge from the low side of the system

[Click4]

Hi, Thanks for the reply, ok will try to add the remaining refrigerant through the low side as vapour gas.

I know it has 470grams in it at the moment, so just need to add another 340grams through the low side.

Next question is, is it normal for it to be hard to pull down less than 2000 microns on a car?

Im new to this, and only done a few cars so far.. they hold vacuum and pressure but wont go down below 2000microns.. I got my own car down to 1000 but it needed a vacuum for nearly 3 hours.

My understanding was, 2000-3000 microns would indicate possible leak, 1000-2000 microns would indicate moisture present, and anything below 1000 would be ideal lol as 500 microns existing oil also starts to boil off but reaching 1000 seems to illude me so far unless using a vacuum pump for extended periods of time. But so far because ive been unable to pull easily less than 2000 microns that had been my target. so I just vacuum until im down to that as long as it takes, rather than saying vacuum for 20 minutes etc.

Is it because of the schrader valves?

Ive got a tool on order at the moment to remove them and re-install without compromising vacuum or pressure.. so will see what my vacuums are like then by removing the valves, vacuuming, then reinstalling them prior to gassing.

If I isolate the car and pull through my hoses and manifold it easily and quickly pulls down below 400 microns so no leak on my equipment.

Would I be able to also get it lower, by trying to pull a reasonable vacuum, flushing with nitrogen then vacuuming again? to flush out more moisture from the system... never seen or heard of anybody doing this on cars though personally.

[install monkey]

if its 134a charge in liquid phase, just charge it slowly in the suction line- not as a vapour
triple vaccing with nitrogen will help shift moisture.
anything with a schraeder core will slow the vaccing performance- core removal tools and vaccing with a 3/8 line from the vac pump to the manifold(usually a 4 way manifold) as for everything elso i dont do cars so i couldnt comment

[Brian_UK]

Also keep changing your vac pump oil, you should be able to get a lot lower than 400micron on your gauges alone.

[Click4]

Hi, Thanks for all the advice and help so far

Vacuum pump does go down a lot lower than that, just after it got to about 400 microns that satisfied me that there was no leaks on the manifold or equipment.

found it a lot easier now to get down below 200 microns and 29.9 vacuum today by vacuuming, breaking the vacuum with nitrogen, then vacuuming again.

Because I did that this afternoon when I recovered the refrigerant to start trying to recharge it again.

I tried my tank heater this time, and it increased the pressure and managed to liquid charge it easily.

Dont know if that was wrong though as I know the advice on here was to charge on low side slowly....but i hadnt tried the heater blanket yet, and so I thought id try that quickly first.. and the correct weight of charge went in fine.

Compressor kicked in, and was working fine, I got a temperature down to 3 degrees at the vents.

But I still dont think its right.. theres a problem somewhere im sure of it... because watching the digital manifold, low side seemed fine the pressures did.

But the condenser fan keeps cutting in and out, pressure on high side climbs to 300psi, fan kicks in, brings it back down to normal levels, then fan cuts out again and pressure starts increasing and it keeps doing that in a loop.

Then after taking it for a drive, it wont cut in at all, redid it all again.. with correct weight again and again it works perfectly fine to begin with... but after a while stops working... theres no leaks ive had the nitrogen on it, pulled it down to a 29.9 vacuum and 1500 microns and everything is holding fine.

[Click4]

previous post should of said below 2000 microns.. not 200 lol

[Tayters]

Condenser fan is probably controlled by a switch in the discharge line somewhere which is why it cycles. After the drive and it not running indicates the fan recieving a 12V run feed and fan faulty or the feed isn't getting there in the first place.
You may find the AC is controlled through a module somewhere - this may run the fan at 2 different speeds which are normally switched on the neutral side.

[Click4]

Condenser fan is probably controlled by a switch in the discharge line somewhere which is why it cycles. After the drive and it not running indicates the fan recieving a 12V run feed and fan faulty or the feed isn't getting there in the first place.
You may find the AC is controlled through a module somewhere - this may run the fan at 2 different speeds which are normally switched on the neutral side.

Hi thanks for the reply.

Yep fan is controlled by discharge line switch I'd imagine as it kicks in at around 300 psi then goes off when levels are down to normal again.

Because when going along it probably doesn't cut in at all because of the airflow through the condenser.

Will check again Tommorow when everything has cooled down, my hunch is something electrical it getting hot and breaking down somewhere.

Not sure if it's fan related as when it's working compressor kicks in first, pressure increases to 300psi on discharge line then fan cuts in second when it's working.

But when it stops working, compressor is not even kicking in, with good pressures on high and low side.

[Tayters]

But when it stops working, compressor is not even kicking in, with good pressures on high and low side.

Ah in that case then it looks like you are losing the A/C run signal for starters. I think you need to find out how the compressor coil is activated electrically be it through a module or relay.

What vehicle is it?

[Click4]

Lol knowing my luck it will be a module as it has digital climate control and twin fans.

It's a 2001 MK3 Ford Mondeo.

I think heat must be playing some part in it, as it works initially then stops after a while like an electrical component is breaking down.

[Tayters]

No familiar with a mundaneo set up I'm afraid. When it stops running are you getting a feed to the compressor clutch?

[Click4]

No familiar with a mundaneo set up I'm afraid. When it stops running are you getting a feed to the compressor clutch?

Hi, haven't checked that yet, will unplug the compressor Tommorow and check for some voltage

It's a strange problem lol, was quite happy once I got the refrigerant in and it was down to 3 degrees at the vents.

Then it just stops working

Will also see if any fault codes are logged by the PCM that are readable by an obd scanner.

[Click4]

Hi, haven't checked that yet, will unplug the compressor Tommorow and check for some voltage

It's a strange problem lol, was quite happy once I got the refrigerant in and it was down to 3 degrees at the vents.

Then it just stops working

Will also see if any fault codes are logged by the PCM that are readable by an obd scanner.

Just checked it again, worked fine again initially for first 10 minutes.

Unplugged the power connector and the compressor is recieving power... so looks like a problem with either the wires on the outside of the compressor.. or a problem with the electro magnet inside the clutch mechanism.

Thanks for the help and advice

[hyperion]

If the system is running and tripping out after 10 minutes, possibly the dx matrix is getting down cold enough and the safety de-ice control is breaking the circuit. Normally this just a sensor onto the control module. If you are getting 3 degC at the vents, then that is a lot colder than you would normally expect and could be the reason for the de-ice safety cut-out operating.
Electro clutch normally either works or doesn't. There could be an intermittent wiring connection that is causing the problem.

[Click4]

If the system is running and tripping out after 10 minutes, possibly the dx matrix is getting down cold enough and the safety de-ice control is breaking the circuit. Normally this just a sensor onto the control module. If you are getting 3 degC at the vents, then that is a lot colder than you would normally expect and could be the reason for the de-ice safety cut-out operating.
Electro clutch normally either works or doesn't. There could be an intermittent wiring connection that is causing the problem.

Hi it could be a bad wire on the compressor because the loom doesn't connect directly into the compressor it connects into a small bit a of wire about 3-4" long that goes into the compressor clutch, there's also another wire coming out of the clutch going towards the back of the compressor so I'm wondering if that's getting hot and resistance is increasing creating a fault.. As it's right next to some coolant hoses and the engine block.

Regarding the ice cutout, once the temperature increases wouldn't it reset and kick in again?

Earlier it cut out while driving, but didn't work until I got back and left the engine off for a few minutes.

[Click4]

Is it unusual to get 3 degrees at the vents?

I just tested my focus, shoved a temperature probe in the centre vent, low fan speed.. Went for a drive and it recorded a lowest temperature of 3.6 degrees. So only half a degree more than the mondeo roughly.

Low temperatures might be because I vacuum down to 2000 microns for minimal moisture.

[ianbaircon]

check the air gap between the clutch plate if the gap is large the comp run when cool but when the comp gets hot the gap gets bigger and the electro magnetic coil will not p ull the plate in too drive the comp

[Tayters]

If you have a feed to the coil then as Ian says there could be a fualt with the air gap - I think Volvo's amongst others suffered with that.
To test the coil measure it for resistance. I think the one on our Astra was around 150 ohms. You'd need to check it when it is getting a feed but not cutiing in.

Cheers,
Andy.

[Click4]

Hi, just thought id post back.

Got a shim kit from Ford for the car, had 1 of each size in the kit then re-shimed the clutch plate.. it must be quite worn as I ended up using the thinnest shim in the kit, its not binding with that and there is still an air gap.

lol learn with experience though, cost £9, then after I realised I could of got a whole box online with various sizes in multiple quantites for not much more.

And as above, managed to get all the gas in with a tank heater must be the system design which restricts it because it seems to be common on mondeos not being able to get all the gas in without a heater or low side charging.

So alls well and working fine now.

Today I found another little tool I need to invest in though, lol spring lock decoupling tool... ironically i ordered a springlock set when i setup thinking if i got a set it would have everything in it.. but seems to be that the set I ordered (despite coming from an aircon supplies seller) was only covering the kind of sizes used on fuel lines so I came a bit stuck when doing an accumulator and condenser, luckily it was on an accumulator and I was changing that anyway with the condenser.. but got them undone with a bit of improvisation.

But still learning as I go along so all good experience.. im finding the vacuum process quite interesting though.... I go to cars, pressure test them to 150psi with OFN.. use leak detector spray, no leaks found, then I vacuum it.. everything holds vacuum fine.

However its interesting to see how you can go to 1 car which will vacuum down below 2000 microns quite quickly with it being down there after 30 minutes almost, so in those situations I just give it the 40-60 minutes anyway which brings it down to 1500 microns then, another you struggle to get below 2500, and another car might vacuum for just over an hour to hit 2000 microns.

I gather if it wont go below 3000 that normally indicates a leak? so they cant be really leaking if its heading down to 2000, and from what I can tell 1000-2000 is the moisture present indication range but in terms of practicality theres no way to get it down to 1000.. I got it down to that on my car took 2-3 hours thereabouts lol. So I just set myself a target of 2000 microns.

But if it takes 1 hour to get down to 2000 microns, no idea how some are doing a proper job when they quote 20 minutes for entire job.. saw 1 person advertising on their website they vacuum for 1 hour down to 500 microns and thought to myself that seems impossible...

Thanks again everyone for being friendly and offering great advice and help its much appreciated.

[charlie patt]

mondeos suffer with coil pack issues start from cold no problem then when hot wont cut in if it wont cut in after a timed period check temp on bottom of comp if more than 68dc the thermal klixon will cut out on comp thus loose the power to comp also if ice klixon cutting in put the heater on a little this will keep the evap clear three degrees on a mondeo is not a problem but hitting 300psi on head in this ambient is unless you are in a 30 dc garage i would say you have lost slow speed on a fan ie resistors gone the shim gap will assist the gap issue but will only delay the problem, if you simply aint geting the power to the comp they suffer from wot sensor faults buit via the throttle thermistor sends signal to ecu sytem also overcharged should hold 745 for english enviroment the vacumn issue could be due to mutiple gas charging or being a mondeo the condensor is pourous

[Click4]

mondeos suffer with coil pack issues start from cold no problem then when hot wont cut in if it wont cut in after a timed period check temp on bottom of comp if more than 68dc the thermal klixon will cut out on comp thus loose the power to comp also if ice klixon cutting in put the heater on a little this will keep the evap clear three degrees on a mondeo is not a problem but hitting 300psi on head in this ambient is unless you are in a 30 dc garage i would say you have lost slow speed on a fan ie resistors gone the shim gap will assist the gap issue but will only delay the problem, if you simply aint geting the power to the comp they suffer from wot sensor faults buit via the throttle thermistor sends signal to ecu sytem also overcharged should hold 745 for english enviroment the vacumn issue could be due to mutiple gas charging or being a mondeo the condensor is pourous

Hi, compressor is running continuously now fine so in this instance it was the shims.

Will check low speed fan resistor, it's not overcharged because I have a device which automatically cuts off the refrigerant when correct weight is added it's rigged to the scales.

Also when fan cuts in the pressure drops down to normal levels.

Could be low speed fan problem, resister is bottom corner of radiator can cowling if I can remember. Because when pressure drops fan cuts out again.

I'm not bodging these cars up just still learning as I go along hence why I've not left that mondeo yet until its right, belongs to family member anyway. Lol

Regarding vacuum if you are saying it should go down to 745 microns I've never got that yet.. And on 1 car I put a new condenser in, new reciever drier, then went around the system replacing every o ring because it hadn't been gassed since new, car is a 2000 reg and bottom of condenser was shot.

But even with new condenser and seals all round (which I lubricated with pag oil) it passed a OFN test and vacuum test fine but after just over 1 hour was still only at 1500 microns... Pulled down quicker probably because it had a new drier rather than a depleted one I guess. But none the less with a new condenser and o rings all round changed 13 in total.

2 on compressor, 1 on the orifice tube, 6 on the reciever drier springlock coupling pair, 2 on condenser, 2 on bulkhead.

Even shoved new orifice tube in and 2 new shrader valves. Because I figured with it being unused for that long better to change all the seals to ensure no leaks from dried up seals.

But was still only able to achieve 1500 microns in just over an hour. So I figured for a car it's normal to be around 1500 - 2000 because also not to forget the system is also full of oil also which probably skews the readings a bit.

Nothing wrong with vacuum pump, I vacuumed my recovery cylinder down below 500 microns with it originally.

[charlie patt]

every time the system is broken the oil is dragging in moisture was ofn check overnight as we have found some condensors will only leak when condensor gets warm also most systems are runing at 300 psi so a 150 ofn sometimes aint enough this is why we are moveing over to a helium mix and leaving overnight if any doubt also if you are useing ofn it does act a partial drying agent thus reduceing vac time. if a vechicle has a week front seal a poor vac is sometimes a symtom but it also depends on power of vac pump number of regases in history condition of vac oil age of system and ambient air there are countless ways of assisting a better vac weather it being time or heat on a previous note it says charge to 810 grams it should be 745 useually minus 10 percent for uk or plus 10 percent for warm ambient unless you are in a red hot workshop that mondeo should not be hitting 300 psi head even with low speed out you have proved your pump but wg=hat cfm is vac pump?

[Click4]

Hi,

Thanks for the reply.

300 Psi im sure will be fixed once the slow speed fan resistor has been fixed ive enquired about one with ford, £48, not been overfilled because when the fan does kick in it drops dramatically into a normal pressure.

I thought for automotive systems 150psi was about the max that is supposed to be put through it? to prevent compressor reed valve damage and damage to the reciever drier? could be wrong?

lol im kinda desperately trying to learn and pick things up and do things properly im the kinda person who doesnt like taking short cuts.. Ive got the micron guage and everything which others dont use... just on the training they dont teach you about these little things so it comes from experience.

Vacuum pump oil I change that regularly, once to twice a month or whenever I notice a drop in vacuum performance. its a 10cfm dual stage vacuum pump which is rated down to 50 microns.

when vacuuming, I would really love to be able to remove the shraders, but I cant find a tool here in the UK that allows you to remove, and attach a vacuum hose to vacuum.. then re-install without compromising the vacuum.. I think that would greatly help getting a lower micron reading quicker.

Ive got a tool at the moment for changing shrader valves under pressure on fully gassed system which works well, but theres no way of attaching a vacuum hose to the tool once the valve has been removed.. was thinking of getting a brass fitting machined to do this but i figure the cost might be too much.



Just looked again actually, and wondering if this will fit with the above to do what I need.



Probably also if I can get a pair of shorter manifold hoses it would help as well, got 72" ones at the moment which to be fair for what im using it for is a bit too long.

Digital manifold has an inbuilt T for the micron guage, so thats where i have been attaching it but could be hoses are too long so its effecting the reading.

[hyperion]

Are you using a normal 1/4" gauge line to the vac pump or using a 3/8"? If you use the 3/8" this should speed up the vacuum time considerably.

[Click4]

1/4"

most of the automotive stuff is all 1/4" id have to buy a new manifold for 3/8" because I got a digital one with all the car data programmed into it.

[hyperion]

Often the four port gauge manifolds have an option of using a 1/4" or 3/8" line from the manifold to the vacuum pump. This reduces the time taken to pull a good vacuum as if you are using two 1/4" lines from the car and a 1/4" line to the pump, this can cause quite a restriction.

[Click4]

Would it make much difference if I was to convert to 3/8" hoses and just use 1/4" adaptors on each end for the couplers and manifold?

I know the manifold would still be a restriction and the couplers.. but the hoses in 3/8" should ease that restriction a bit.

[charlie patt]

a vac is only as good as your smallest retriction try a set of 4 lines with a large vac hose ,,,, most fans will keep up with a overcharged unit untill a hot day comes / 250 300 psi is max hp test but no damage occurs as long as it does not run alfas on the high side will run at 350 high side and all parts designed to withstand 3x standing pressure so on a warm day 134 in HOT VECHICLE WITH A FULL CHARGE will be aprox 120 psi so no issues there, personally i would not get into removeing cores mainly due to galaxys have rubber seats below the core valve and when you remove core they drop into system been there done that / with a 10 cfm pump thats enough to suck your grannys teeth out if you cant pull a vac on that its loaded with moisture or there is a leak if it passes a hp test and wont pull a decent vac the front seal is leaking

[Click4]

True, just thought if you reduce the overall restriction with 3/8" hoses on a 1/4" manifold, while it wont be as good as a 3/8" manifold it should be better than 1/4" hoses on a 1/4" manifold.

No damage should occur anyway, because there is always the high pressure switch, which is designed to cut off the system if pressure gets too high... in theory lol.

I havent done a galaxy, but I thought all of the valve cores had this rubber seal on the bottom of the valve? might of been in your case that it got stuck and as the valve was unscrewed it pulled off and dropped down.

I had that problem with 1 of my bits of equipment.. lol I removed the valve core to reduce the restriction as I didnt need it.. as I unscrewed it, pulled the rubber seal off it and it dropped inside.

So that is a nuisance if it does happen, but in some circumstances if valve core is leaking surely it should be changed regardless?

When I check them ive come accross a few which have been weeping on cars, 1 car even it was bent! lol

you would think so! lol but could be the front seals.. not a lot i can do about them they should reseal themselves with use.. if not compressor needs changing or rebuilding with new seals.

[Click4]

At6 first check the heat removal section inside the car.There are many reasons your air conditioner can blow warm air. A basic a/c gauge and test light is needed to help diagnose most air conditioner problems. Always use caution when inspecting an air conditioner system, a/c systems contain high pressure gas that when released can cause personal injury. Use all safety precautions. .

Car is not blowing warm air, it blows air down to 2.5 degrees celcius.

I have a digital guage with all car data programmed into it, and a digital leak detector which sniffs refrigerant and combines a uv lamp. But the system is not leaking anyway and working correctly bar the 1st fan speed not working which is causing a high pressure buildup until the 2nd fan speed kicks in.

I know about the precautions, I spend hundreds of £s on training to achieve an F gas qualification so I can operate legally, the training included a lot on the risks and health and safety to avoid personal injury and the effects on the environment.

[Amma]

OK,well one option to test if it is the high pressure switch that is not allowing to the compressor to run,and that indeed your pressures are too dangerously high,is to briefly jump the connection with the high pressure switch out.Before recharging auto air-conditioning systems it is recommended to remove any air and moisture from the system.If you have more confusion so i think you should consult to a technician.Thanks.

[Click4]

OK,well one option to test if it is the high pressure switch that is not allowing to the compressor to run,and that indeed your pressures are too dangerously high,is to briefly jump the connection with the high pressure switch out.Before recharging auto air-conditioning systems it is recommended to remove any air and moisture from the system.If you have more confusion so i think you should consult to a technician.Thanks.

Hi,

it is the resister on the radiator, the low fan speed has burnt out and a replacement is £50.

Once I install that im sure the problem will be fixed, only reason it is increasing to dangerous pressure is because low fan speed is not cutting in.

then when it gets too high high speed fan is cutting in to protect the system... then when pressure drops below danger level high speed fan cuts out.

I am a qualified technician so I know I need to remove moisture from the system, but that is not the problem here.

[charlie patt]

it depends on what you call high pressure sorting low speed on condensor fan wont radically help the problem the high speed will cut in and counteract when you have lost low speed unless your ambient is more than aprox 22dc also when driveing along the natural wind speed alows for this even with just high speed your cooling should be good pressue switch wont trip hp until aprox 100 psi more than when high speed fan cuts in if high spped fan in and head still creeps up and up and up you still have high head pressure faults and a low speed fan wont help that just maybe delay it longer is the fault you loose cooling or the head is to high?

[Click4]

Problem is,

Pressures at normal pressure with air conditioning off

Switch on Air Conditioning, Fan doesn't start up, because low speed fan resistor is dead

Pressure creeps up

High Speed Fan cuts in

Pressure drops and returns to normal until fan cuts out.

[charlie patt]

So whats the problem? High speed overrides when head creeps up when driving on the road the air does what low speed does by the fan im trying to work out if your worried the head is to high? As above comments low speed resistor wont help this

[Click4]

low speed fan should cure it, because it will mean the low speed fan will kick in as soon as the air conditioning is switched on so it shouldn't creep up to the high pressures any more.

[charlie patt]

thats what i said on about the fourth thread