A/C pressure test?

141 Views 3 Replies 4 Participants Last post by TheAntman, 6 d ago

HomerJay

Discussion Starter · 7 d ago

Hello.

I bought a 57 plate Mondeo to get to work and the only thing wrong with it was the A/C didn't work. I have had the car for 18 months now and thought it might be nice to have some cold air for the Summer.

Took it to my usual mechanic for a regas but it was clear that the system wouldn't hold pressure so left it at that thinking I would research online. I have seen the home refil cans with UV dye which show up where the leaks are but I was wondering if there is any other way of testing the system as I don't really want to chuck money away on refil cans knowing that it's all going to leak out. I have no idea how long it has been since the A/C was working so it could be anything...

Thanks.

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mondy zetecs

· #2 · 6 d ago

Took mine to Kwikfit cost under £60 as mine has not worked for 15yrs, mine held pressure for a couple of months,there is cannisters on ebay for leaks and regas, have to identify which gas eg. R134 ,R1234 the car uses, Halfords does a guage shows what amount of pressure is gassed into the system, all in about £75 (priced last year) to do your own,i might try a diy leak and regas with the guage, there is the normal guages that come with the regas cannisters ebay.
Usual leaks are from corroded condensor/radiator or could be rubber seals.

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Master-of-none

· #3 · 6 d ago

An A/C specialist should use nitrogen or helium under pressure to find the leak (it's expensive [& possibly illegal] to use refrigerant for leak checking on a known bad system).
You could use compressed air* instead if you can find suitable a connector, squirt diluted detergent or similar at the system.
Most A/C leaks are from impact damage to, or corrosion of the condenser.
It's much easier to find leaks under high positive pressure rather than the vacuum check performed by A/C charging machines.

*yes it may be moist but the system has been at zero pressure for years, so is likely to already be contaminated.

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TheAntman

· #4 · 6 d ago

Master-of-none said:
An A/C specialist should use nitrogen or helium under pressure to find the leak (it's expensive [& possibly illegal] to use refrigerant for leak checking on a known bad system).
You could use compressed air* instead if you can find suitable a connector, squirt diluted detergent or similar at the system.
Most A/C leaks are from impact damage to, or corrosion of the condenser.
It's much easier to find leaks under high positive pressure rather than the vacuum check performed by A/C charging machines.

*yes it may be moist but the system has been at zero pressure for years, so is likely to already be contaminated.

It is indeed illegal to do so.
It is also illegal for anyone who is not certified to handle R134a to tamper with a charged AC system or handle R134a refrigerant, however, many of these refill cans contain a R134a equivalent that is environmentally friendly, safe to use, and doesn't require the same certification, however, you should still not be filling a system you know to have leaks.

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