Car Air Con - 2nd opinion

[Click4]

Hi, just wondered if I could get a 2nd opinion, much appreciated and thanks in advance.

Went to a mk1.5 ford galaxy today, basically same car as the seat and VW sharan.

Vacuumed it for an hour, so no air in system.

This model had 2nd evaporator because of the pipes running under the car.

Compressor kicked in fine, fan works fine.

Condenser visually looks to be in good condition.


However, it was exhibiting overcharged pressures. 220psi on high side, and around 70 psi on low side.

Compared to previous same model car for another customer which was, 25psi and 132psi.

It seemed like it was overcharged, so I tried recovering some refrigerant dropping it right down to 500g, but it mad no difference.

With hardly any cooling from front vents. Rear pipes had some condensation and felt cold on the suction line.

At first I thought it could be a stuck expansion valve, but stuck closed would cause high, high side pressures and low suction pressures.

And if stuck open then the high pressures wouldn't be so high either.

So then I measured the in high temp high pressure vapour pipe where it goes into condenser because its scalding hot, came out at almost 40 degrees, then measured liquid pipe from condenser and temp was around the same, which it shouldn't be... Was using a laser thermometer.

So does it sound like a blocked condenser? Or maybe internally it's ruptured and so instead of condensing into liquid the high temp vapour is bridging accross and coming out as a vapour.

Fan is working so its only thing I can think of.

Now removed the gas until I can fix it.
Thanks.

[hyperion]

Seem to recall hearing that these systems sometimes suffered from oil entrapment because of the extended pipework and second evaporator.
However the pressures sound more like non condensables. Are you sure that there is no chance of any OFN having been trapped and thereby causing the higher pressures.

[Click4]

Seem to recall hearing that these systems sometimes suffered from oil entrapment because of the extended pipework and second evaporator.
However the pressures sound more like non condensables. Are you sure that there is no chance of any OFN having been trapped and thereby causing the higher pressures.

Hi,

I vacuumed it for an hour so shouldn't be, it was vacuumed to quite a deep vacuum.

Of course it's hard to say, but after it wasn't right first time, I recovered the gas, vacuumed it a 2nd time and tried again but made no difference.

The high pressure high temp pipe though seemed quite hot, scalding in fact. But that's probabaly due to high pressures.

But the liquid pipe from condenser was also hot according to my laser thermometer.
Which was what made me think the refrigerant wasn't condensing properly causing high pressures.

[The Viking]

As you got the same temperatures entering as leaving the condenser (but contact thermometers are better than IR ones to verify this) there can't be any liquid in the condenser...
If the refrigerant entering the expansion device is in a vapour state (-no liquid in the condenser) there will be little pressure reduction and the pressures might become elevated.

Are you sure this system isn't in fact under charged?

:cool:

[Click4]

As you got the same temperatures entering as leaving the condenser (but contact thermometers are better than IR ones to verify this) there can't be any liquid in the condenser...
If the refrigerant entering the expansion device is in a vapour state (-no liquid in the condenser) there will be little pressure reduction and the pressures might become elevated.

Are you sure this system isn't in fact under charged?

:cool:

Hi, yep contact ones are better, when I go back will vacuum and try recharging it again then use a contact thermometer. It was so hot it was scalding (on the pipe from compressor to condenser.)

The single evaporator only holds around 700g can't remember exact figure now from top of head but its between 700-750g. Dual holds 1025g.

Yes it would of been undercharged, because it took in the amout for a single evaporator fine in liquid state through high side... But wouldn't take any more, and i dont like to force more in unless i can see what pressures are doing, as on some cars its hard to tell if songle or dial setup (although this one you could see pipes under the car) so I started it up to flash the rest in as a vapour through low side. However, because of the high pressures and lack of cooling I stopped charging, because even undercharged it should of had some noticeable cooling and lower pressures than that. As it still had around 75% charge, the above procedure worked fine on another identical car I did a few weeks ago and didnt exhibit these symptoms.

That's why I'm wondering if there is something wrong with the condenser, because like you say it's like it's not condensing properly into a liquid. I feel this is also slightly confirmed by the fact that the rear evaporator seems to be working better than front one (was condensation on the suction pipe under the car) and only reason I could think of for this is that because of the length of the pipe the refrigerant is condensing inside.

On outside condenser looks fine but it could have some kind of internal blockage or fault.

This is I feel also why the pipe is scalding hot, because no cooling is occurring at the expansion device, it's just recirculating , picking up more heat day time it goes through compressor and not loosing it through expansion from liquid to vapour.

[Craig Flello]

Are you adamant there are no non condensables in the system did you use a torr gauge of some description and what level of torr did you achieve?

[Click4]

I use a micron guage and vacuumed for an hour.

Got down to 1300 microns.

Which is still quite high but without removing shraders I haven't managed to get lower on any car within an hour or so.

Also it's connected up by the gauges which makes it read slightly higher also. Not convinced that non condensibles is the problem unless there's some kind of blockage holding them back.

An hour vacuum is already longer than most.

My vacuum pump is also 10cfm

[Neddy]

Has it got one or two expansion devices? I would imagine its got two . One may be faulty. Are you using new refrigerant or recovered refrigerant?

[charlie patt]

forget that.... comp is shot or over oiled you can still get good head but suction too high galaxys hate being empty and comps just wont pump after a period of being empty on mk1 and 2 s you will prob find drier leaking also ... ive had um at 300 head after disconecting fan suction still to high pull comp of measure oil if level ok comp faulty new type clutchless suffer from same issue

[Click4]

Has it got one or two expansion devices? I would imagine its got two . One may be faulty. Are you using new refrigerant or recovered refrigerant?
2, and using new refrigerant.


Is there any way I can confirm the problem?

Now have possibilities, compressor, expansion valve and condenser.

Lol can't change them all because it would be too expensive and id be guessing.

[Neddy]

Is the clutch on the compressor cutting in and out ok? If its engaged for too long it might be causing higher pressures. Not sure how they are controlled as I never work on motors!

[charlie patt]

condensor is fine as you have high suction expansion valve ok as you would have cooling on one of the units or if one butchered the head would be low the suction is high and head variable pull gas out and flow check it if pressures level realyl quick comp is shot on a twin you can also drop out about 450 grms it should trip lp all the time but being a bad pumper it wont

[Click4]

Thanks for replies and help and advice so far, much appreciated.

So you think it's a compressor problem, if I can confirm it, then there's one on ebay at the moment for £50. But need to be sure as they don't allow returns.

So if I drop it down to 450g, then I'm assuming the test you propose is that a good compressor will pull suction pressures down below the low cutout threshold? So will suck down until pressure drops too much... Cut out, then pressure will equalise and compressor will kick back in.

But if its a dodgy compressor, it will never pull down to a low suction pressure as high pressure side will always be bleeding backwards to the low side?

[charlie patt]

yep avoid secondhand they very rarely work link out lp and run it a good comp will pull vac and level slowly a bad comp wont and level quickly two thinks with a galaxy it will have a leak and comps pack up easily when been empty you repair leak vac it gas it and it pulls down to 13 dc approx then starts rising classic comp/ oil issues

[Click4]

Thanks, startin to realise how bad these are now.

Went to one today, galaxy, gassed it, and with compressor running pressure was equal on both high and low side, just wasn't generating a pressure differential.