Recommended Posts

Having read through the archives, I seem doomed to join the ranks of those with aircon troubles. Earlier this year I noticed the aircon wasn't pushing out any cold air so thought i'd give one of the home top-up kits a go.

With the engine running and aircon on full cold, i connected up the gauge to the Low pressure valve and sure enough it was registering nothing. I added a small amount of refrigerant to take the reading from nothing up to 'ok' When i reached OK, the engine changed from a slow to a fast idle (presumably because presurising the system put a load on the compressor and the engine compensated) but then the pressure went down to zero.

Switching off the aircon and engine, then repeating the process, still shows no pressure on the aircon pressure gauge. Should I assume there's a good leak somewhere?

Oddly, with the engine running but the aircon switched OFF, the gauge when connected to the Low Pressure valve indicates a good pressure. It's only when i hit the AC button in the cabin to switch it on that the pressure drops down to nothing. Can anyone explain what's happening or how the system works for me to get these readings? I'd expect them to be the other way round (if the system was working) or for both to be nothing (if it wasn't)

I'm starting to accept that an expensive trip to Lexus Guildford may be in order if i ever want air-conditioned air again :crybaby:

On the plus side, I've just given the car an oilchange (that oil filter is in a blooming annoying position) and will be treating it to a well-deserved coolant/plugs/leads change when Lexus get the leads in.

Many thanks for any help

Darren

Share this post


Link to post
Share on other sites

Darren - DON'T GIVE UP & GO TO LEXUS!!

You were on the right track and I did exactly the same thing as you. But when revs changed and pressure dropped I carried on pumping in refrigerant and pressure gradually started coming up from zero. It took a long time but it eventually it got to the ok zone and has been working fine for over a week now.

My initial pressure was zero and the sight glass was clear so mine was empty. I did therefore think there must be a leak but I used the pressure guage to test yesterday and it looks to be the same. I can only conclude that although there must be a small leak somewhere it took a few years to empty out and that the sealant in the Halfords EZ cool can has been enough to seal it up.

IMHO what is actually happening is that when the system is empty the compressor won't run. You connect into the circuit via the tyre type valve and you register zero pressure - understandable its empty. You pump into a limited volume space as the circuit is closed and the pressure builds up quickly. Sensing the coolant in the system the compressor kicks in and hence your revs change as the engione takes the load. The system is now a complete circuit and you're connected to the full volume of the aircon system hence the pressure drops back to (apparent) zero.

If at this point you persevere the coolant will very gradually build up and you will notice a green swirling chaos of fluid and bubbles rushing past the sight glass in the high pressuree end down at the front of the engine.

Its as the compressor kicks in and opens up the circuit the initial coolant you put in has a much larger space to fill and hence decreasing the pressure that you're giving up thinking something is wrong. Try again. When I did it I thought the system must have already been full and that the extra coolant had blown a seal hence the sudden drop off in pressure.

Good luck!!

Share this post


Link to post
Share on other sites

Ah-ha!!

Thanks a million Preeder. That makes sense. Wish i'd just been a bit more gutsy and kept going. Sounds like that's what I needed to do. I'm going off to the garage to try again....

Could you do me an enormous favour some time and let me know what yours reads on the gauge when the gauge is connected but the aircon isn't on? The only reason I ask is that I did what you suggested but have pretty much run out of refrigerant. I think i was starting to see some movement on the gauge tho and the air *was* slightly cooler. Thing is - when I switched the aircon off, the gauge read well up the yellow range and almost into the red. I don't know if this is normal or not when the aircon is switched off..

To be on the safe side, I depressurised the system a little. I may go out and get another bottle of refrigerant so i can continue testing.

Thanks so much for all your help!

Happy driving..

Darren

Share this post


Link to post
Share on other sites

Yes, with aircon off I'm well up past the yellow (alert zone) into red (for gods sake phone the pentagon) region.

Its worth shaking the can to check whther theres any left, its quite deceptive. The 12inch high can was more than enough to fill my system up from nothing.

Share this post


Link to post
Share on other sites
Yes, with aircon off I'm well up past the yellow (alert zone) into red (for gods sake phone the pentagon) region.

Its worth shaking the can to check whther theres any left, its quite deceptive. The 12inch high can was more than enough to fill my system up from nothing.

Had mine tested and regassed by local aircon specialist 2 years ago. When I collected the car they had it on test with a/c on and it was icy cold . worked fantastic ever since. Cost £ 74. inc VAT. Much easier and they know what they are looking for regarding leaks or possible compressor damage. Quite possibly cheaper in the long term.

Share this post


Link to post
Share on other sites

Thanks guys..

Dave, £74 sounds very reasonable. I'd imagined it'd be more. If mine turns out to be a different issue and preeder's solution doesn't work fo rme, i'll go the local aircon specialist route - the big advantage as you say is that they obviously know what they're doing..

Brett - the actual refrigerant cans are about 19.99 - the 40 quid pack contains a can plus the dispenser and gauge which you can resue if necessary.

All the best,

Darren

Share this post


Link to post
Share on other sites
Thanks guys..

Dave, £74 sounds very reasonable. I'd imagined it'd be more. If mine turns out to be a different issue and preeder's solution doesn't work fo rme, i'll go the local aircon specialist route - the big advantage as you say is that they obviously know what they're doing..

Brett - the actual refrigerant cans are about 19.99 - the 40 quid pack contains a can plus the dispenser and gauge which you can resue if necessary.

All the best,

Darren

V.R.S. Coventry, apparently they actually do some work for Lexus, but they deal with all makes, but a lot cheaper than Lexus dealer. Most biggish towns have 2 or 3 a/c places so its best to shop around , also make sure they offer a warranty.

Regards Dave

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this