Car A/C Questions

[Z2TT]

Hello, I am new to these forums and looks like a great place to learn. I have a few questions if you people don't mind.

1. We had a Lexus that needed a regas, so we brought it to the shop and they leak
tested the system with nitrogen first and it held the charge for half an hour, they also checked
around the engine bay with a UV light for leaks and found none. so they went
ahead and regassed our car. It worked for about 2 weeks but we smelt a weird smell in the
cabin, then it stopped cooling, the a/c still kicks in but it's not as cool, so we must have a leak.
I'm wondering when they do the nitrogen test, do they turn the air con on and let it circulate
everywhere, or just have it sitting there?. I'm wondering if they did a nitrogen test and it
held the pressure, why do I have a leak.

2. Reciever Driers, do they need to be replaced with every re-gas? Is it a common practice and how long do they last?

3. When changing compressors, How tight do I tighten the bolts for the a/c lines to the compressor, is there any chance I'll snap the 0-ring if they are too tight?
and how do I ensure that the O-ring seal will seal well when I replace them?

4. I used to have a Nissan Pulsar that would turn the Air con on every time I put the car into reverse and the same with another car, I think it's some sort of feature to cycle the air con every once in a while to keep it working. Is it true that the air con should be run every so often otherwise the seals will dry up or something along those lines?


Thanks.

[syk35]

1. My guess is that you have a leak on the evaporator and when they pressure tested with nitrogen they didn't leave it long enough to notice the loss in pressure.


2. Driers are changed every time the system is "opened" (eg. pressure testing, re-gassing, replacing components)

3. look in a service manual for correct torque settings and ensure new o rings are used.

4. Yes it is good to operate compressors with shaft seals regularly to help reduce the seals from leaking

[Z2TT]

What could happen if I dont change the drier after I have changed my A/C Compressor?

I have heard of some products that are put into the gas that can seal up leaks such as cliplight, can I get the shop to put some of this in next time I get it regassed and will this help?

THanks.

[Z2TT]

Also is it ok to replace a reciever/drier the day before I get the car re-gassed, or should it be replaced before re-gassing?

[Latte]

The drier needs to be replaced just before the unit is evacuated before regassing. The drier is there to remove moisture in the system and will become saturated in a matter of seconds so fitting it the night before is no help.

I have also seen these leak seal systems and they are becoming more available in the UK, the only thing i can say is the couple of times i have used it it hasnt worked

Regards

Latte

[Voyager]

What could happen if I dont change the drier after I have changed my A/C Compressor?

If the dessicant in the drier has been exposed to atmosphere for more than a couple of minutes, it quickly absorbs moisture and becomes saturated.
If the dessicant can't absorb anymore, moisture will react with the r134a refrigerant to produce hydrochloric acid. You don't want that in the system.


I have heard of some products that are put into the gas that can seal up leaks such as cliplight, can I get the shop to put some of this in next time I get it regassed and will this help?

THanks.

Leak Sealer is the kiss of death to an A/C system. They are designed to harden on contact with air to plug holes. If there is air in the condenser, vaporator valves or compressor, it will plug those as well.

[Z2TT]

I had a read on air condtioning sealants on aircondition.com (google "air condition sealant") and second result.

On the FAQ for "
Will the material clog TXVs, FOTs, VOVs, Schraders, accumulators, driers or any other A/C components?"


For Cliplight it says No.

[lowcool]

i used a product called superseal on a coldplate not long out of warranty a few years ago,have look at the unit now and then if im on the same roof all still seems good,i believe they also make one for auto applications too.made a similar comment about open driers in a van i took over the response was put em on a vac pump didnt push it any further regarding possible rust etc inside of shell.

[Z2TT]

That must be Cliplight Superseal, they sell that at my auto parts shop. I would post the link that compares sealants on aircondition.com but I require 15 posts in order to do that.

The comparison shows that cliplight super seal wont clog any components

[Voyager]

I had a read on air condtioning sealants on aircondition.com (google "air condition sealant") and second result.

On the FAQ for "
Will the material clog TXVs, FOTs, VOVs, Schraders, accumulators, driers or any other A/C components?"


For Cliplight it says No.

I just ploughed through the whole article and one thing comes to mind - all the replies were from the sealant manufacturers. No A/C technicians or end-users, just the people who sell it.

Ask the same questions on www.autoacforum.com and the replies are completely the opposite.

[tbirdtbird]

I think the mfg will tell U what U want to hear. For the long haul I have never seen results of independent testing. I would consider it a crap-shoot. What happens, for example, to the remaining sealer that stays in the system after sealing the leak? Does anyone really know? Do U want it in your vacuum pump? Compressor? I suspect not. Buyer beware.

[lowcool]

on pressure testing i have found that leaks can appear at certain pressures,had a chance to play with a 2 fan coil pumped it up to 200 psi dropped it in the swimming pool no leakage,thought what the hell and slowly reduced pressure as was 100% sure leak was on coil at 50 psi some little bubbles 35 psi lots of bubbles on evap return bend weld.hydrostatic testing is the only way to go.sounds impressive on your paperwork too

[hyperion]

Whilst OFN is good at helping to pinpoint most leaks, there are times when a system with a suspected leak does not display positively to nitrogen pressure due to the molecular size of OFN.
There are thoughts that the 5% hydrogen/nitrogen mix has a smaller molecular structure and therefore can be used to pinpoint smaller leaks at a lower test pressure. Downside is that you need to use a special electronic leak detector.
I have seen this mix in use and it was most impressive in pinpointing a very small leak.
One version is manufactured by the company that sells the lokring components in the UK.

[abbsnowman]

Surprised that nobody has mentioned the compressor shaft seal that will only show a leak under negative pressure. Does it hold vac? Bet not. When engine rpm is up, pressures are low. I see this all the time, holds at 200 psi but not -20.
Just a thought.

[Z2TT]

I had just been talking to some representatives of Cliplight Superseal.
They told me that they sell a lot and that their product has been used widely
in many air conditioning systems.

I wonder why the response is so negative here though?

[Karl Hofmann]

I had just been talking to some representatives of Cliplight Superseal.
They told me that they sell a lot and that their product has been used widely
in many air conditioning systems.

I wonder why the response is so negative here though?


Because it is ****....

When it first appeared in the US round about 2002, I bought a dozen treatments to try with a view to importing it to the UK. Out of the dozen there was only one car that didn't come back. Had issues with the stuff setting in the driers, causing the lube to gel, not sealing and to add insult to injury the stuff played havoc with my recovery gear.

Of course Cliplight will say it is good, they stand to profit from it Doh!

I could have done well from peddling this stuff, but I wont sell stuff that I don't believe in and my albeit limited research has satisfied me that it is worthless and damaging to equipment.

If you want a more positive view, feel free to contact the company that markets the stuff, it's very good for them