lpwwe06 said:

Hello
I have an issue with my 2001 Punto HGT which is a bid odd.
I have replaced the Expansion Valve because previous owner said it was checked in a garage and they 'faulted' it and I replaced the ca dryer as maintenance procedure.
After that (there was no gas in the car) I charged the system with 550g and a bit of oil to see what goes on. after 40 min vacuum (I wanted to be sure it was as clean as I can get it without taking it apart lol), I started the engine and the compressor engaged with a reading of 250 on the high and the low gauges.

Weird thing is, the Air Conditioning was working well, very cold air and I decided to drive a little like this to see what will happen. After a few days of driving I started feeling AC is going off and I hear a hissing sound from the evaporator.

I want to say that the expansion valve is not the highest quality and has been manufactured in Korea and was pretty cheap.

I am very confused by the situation and wanted to get a few experts minds on it (you guys, everybody around here in workshops don't understand deeper than basic stuff.)

So please, any help would be appreciated.

the picture is when the gas was just charged and the readings are really interesting.

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AndyRKett said:

Given the readings you could conclude its likely been over filled.

That sort of pressure on the low side is way way to much and not explained by a poor quality expansion valve.

The recommended charge for your car I believe is 525 - 550, but when adding oil and not knowing what's already in the system I'd tend to go towards the lower end.

The tailing off in the following days is likely because of either an old leak that didn't show up on the vac and hold.

The other possibility is the excess pressure has created a new leak, blown past an old O-ring. I think you may need to look at overhauling all the seals in the system, then recharge at a lower rate.

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judderbar said:

Since the high side and low side are too high and apparently they are same pressure there must be a block on the inlet side of the compressor??

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lpwwe06 said:

Thank you for your reply. Well, that's why I put a little oil with around 540g of refrigerant (maybe 5-7g of oil). I thought about the faulty new expansion valve possibility because that's the only thing that's dropping the pressure from High to Low.
Now I actually am thinking to replace the evaporator, because when I changed the dryer I actually saw it was in a pretty poor condition because I saw the small moisture balls ( I don't know how to call them) that make the dryer to dry, they were all over the place when I flipped the dryer.

It was just like pepper cellar. I think what happened that these particles been pushed and stuck inside the evap. But that still doesn't explain the high-pressure reading on the low side..






Thank you for your reply. I do not know if the compressor is at fault here, I'd like to try a few tests to know that because it is not a cheap part as you know.
If there's a block tho, wouldn't the system not cool at all? and the high side reading is pretty well strangely.

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judderbar said:

Your readings are saying there is no *difference* in pressure so you might as well have no pressure at all.

The pump appears to be working because you have pressure. But without a pressure difference you can have no flow. On the face of it the inlet to the pump is full of rubbish or something and just needs cleaning.

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AndyRKett said:

Thinking this through logically.


The Gas in the system will maybe sit at about 120 - 150 PSI at rest (aircon swiched off) throughout the system as the pressures equalise.

Turn on the compressor and you'd expect to see around 220 PSI like you were seeing. on the high pressure side.

The low pressure side you's see maybe 40 - 50 PSI.

Now you say that you have a new and somewhat questionable expansion valve, and logic dictates that if the expansion valve was stuck wide open then you would get much higher than normal pressures on the low side.

If the dryer was shedding its contents i's expect to see the compressor being damage the expansion valve being blocked and nothing really working rather as the combination of blocked pipes and things would result in an over pressure situation and the compressor clutch would be cut.

But you also report the aircon working well after the regas so that would not suggest a problem with the expansion valve.

My view is that the high reading on the low pressure side is a red herring and something that can happen when regassing the system.

If you disconected the pipes ran the aircon for a while and reconected them I believe you would have seen a more normal reading.

My thought is that a few days later however you did spring a leak.

When you put the gas and oil in, did you add any UV dye?

The only thing you can really do now is look for the leak. what ever the cause you will have to open up the pipe work to fix it, so you might as well check to see if there are any bits of dryer in the pipework, though I suspect not.

I'd probably take the opportunity to replace as many seals in the system as possible as O-rings are cheap and easy to replace. Re gas the system and see what happens from there.

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