More Aircon Misery

[frank rabbets]

After curing all my leaks and having the aircon working it has packed up again. The pump is not disengaging and the high pressure pipe gets VERY hot. I assume I have a blockage. Is this most likely to be in the expansion valve? Could it be a faulty drier dumping dirt into the system? I did put a new one on but not Toyota. Is there a filter to protect the expansion valve other than the drier?. Is is possible to clean the valve and what is to stop it getting blocked again?

Thanks
Frank

 

[DaveN]

Really need to see what the pressures are, that will tell us if there's a blockage. But a blockage doesn't mean high pressure though. Sometimes the dryer is blocked, or more likely contaminated with moisture and freezing. Check to see if it's getting cold. Expansion valve not so common, and they have a little gauze filter to stop large stuff, but of course that can get blocked.

Are you sure it hasn't lost it's gas again?

 

[frank rabbets]

Hi Dave, I have a gauge and will check pressures tomorrow then.
The high pressure outlet pipe gets hot straight away on turning on the aircon right by the compressor but the inlet and outlet points on the evaporator at the bulkhead are ambient temperature.
I did put a new drier in and it was plugged properly. When I opened up the system to take the evaporator out to check for leaks I put small plastic bags over the ends of the pipes and cable ties to prevent dust and moisture getting in. I also taped over the ports to the evaporator before I pulled lt out.

When it lost gas before the compressor did not cut in so I assume there is some gas left.

I'm always so careful and don't usually have this sort of problem with things.

Thanks again.
Frank

 

[frank rabbets]

Hi Dave

I put the gauge on this morning after it had been standing overnight. The low pressure side was 47 psi. I started the engine and turned the aircon on and the gauge fell to 27 psi. There was definately a small amount of cooling. I took it for a run in the hope that airflow through the condenser would improve things but no. Definately some cooling but not enough. Also in traffic the compressor stays on and does not cut in/out like it used to. The outlet high pressure pipe gets very hot; enogh to make you jump when you touch it so I would guess must be 100 c.

The pump outlet feeds the condenser, drier and evaporator in that order.

Your thoughts would much appreciated.

Frank

 

[DaveN]

47 is very low for static pressure. Static pressure will always be the same so long as there is liquid gas in the system (think of a fag lighter, it has the same pressure until it's just about to run out). But at 47 it looks like it's jut got a sniff of gas left in the system, but enough to keep the low pressure switch open (25psi). It doesn't look blocked otherwise it would pull a vacuum on the low side. And the compressor isn't cycling because the evap isn't getting cold enough.

So time for some more leak detection - again!

 

[frank rabbets]

Hi Dave

Thanks for your quick reply. I was wondering how efficient the pump was at pulling a vacuum. Now I know !!

I'll let you know what I find but off to France next Friday and I hate heat.

Frank

 

[frank rabbets]

Hi Dave

Found a leak that is obvious with a UV light which I think they missed on the last regass as there was already UV dye in the system so I'm hopeing for another free regass. This is the only pipe I did not take off but I checked it several times even last night with suds. Bad news is that it's the pipe running across the bulkhead at the rear and you have to cut it in half to get it off or drain the heater system etc. Good news is that its' replacement comes in the form of 2 pipes which you can slide into place.

Booked in for regass on Tuesday and I'll keep posting.

Thanks again for your ideas.

Frank

 

[DaveN]

It's quite usual for that pipe to go where it touches the insulation and rots through. Be sure you get the correct pipes as the toyota number system used to be screwed up and you ended up with 2 halves the same, even with the correct (different) part numbers.

 

[frank rabbets]

OMG
Thats' bound to happen to me. In fact the sheet they faxed over showing the 2 pipes [ 88717A + 88717B ] shows different pipes entirely for the drier area. I wonder what those poor souls do who need the short one going down from the condenser to the drier.

Frank

 

[Jon Wildsmith]

When you have the correct parts let me know the numbers please Frank so I can get some for mine, I might as well change those as well before I gas it up again if they're a common failure.

 

[frank rabbets]

I hope they come with the ...non listed ...O ring for the central join.

Frank

 

[frank rabbets]

Hi Dave, are those led UV lights any good on ebay. If not what would you recommend.

I'll let you know if I crack my aircon faults; or not! Fairly confident now.

Thanks
Frank

 

[Justin_Elliott]

I've got to tackle my Aircon soon - took it for a regas and was told there was no gas left - so I clearly have a leak.

Based upon all your experiences is there a list of parts which should be changed as good pm prior to regas?
Such as a list of the O-rings and their locations, dryer, pipes etc...?? (I presume if the system has sat open/empty for a while the dryer is likely to need replacement?)

Any help / advice on where to start the DIY prep (before paying over the odds for simple tasks) would be appreciated...

 

[frank rabbets]

Hi Justin

My advice would be to take the batteries and trays out so can see all the pipes and joints in situ. Check for any oily patches on the pipes and joints. Then look into the side sight glass. If you have green oil in there the gas probably has ultra violet die and you can further check for leaks with a uv light.

Then take all the pipes off except for the bulkhead one and check all the joints for corrosion which can go past the o ring area making that part scrap. If you have an old/original system you will probably find the condenser joints corroded and also the drier joints but you will definately need a new drier if you open up the system. Keep all the o rings and take them together with a micrometer to an aircon stockist and get IDENTICAL ones or very slightly bigger on the cross section but by no more than .005 inch. Toyota do not list the o rings so you cannot buy a set from them. Don't trust the experts if they try to sell you different o rings. They will leak.

Now for the bulkhead pipe which was my downfall and the experts downfall as it is corroded through at the back where you cannot see. If it is in 2 pieces with a join in the middle then you can take the 2 pieces off and have a careful look. If it is in one piece you may have to drain the engine cooling system. I am just about to take off my bulkhead pipe and will let you know how difficult it is. I ordered the 2 piece pipe option but only one pipe arrived, the correct full length version plus another irrelevant pipe!

When you have all your bits in perfect condition it is a quick job to put it all back together. Remember absolute cleanliness is essential. When you take the pipes off the bulkhead this is the evaporator so remember to put tape over the holes to stop dust getting in. Remember to oil the o rins with silicone oil which you can get out of your old pipes as long as it is clean.

With regards to the evaporator it is probably not worth taking it out unless the joints are corroded and it needs replacing.

Now you will have to rely on the experts. Make sure they put uv dye in the oil and check with a uv light very carefuly starting at the evaporator and going all the way round the pipework and ending up at the evaporator so ensuring that all has been covered.

When you book it in ask if you can observe the procedure or have a mobile man come toy your house. That was where I went wrong and the bulkhead pipe leak was missed twice even though there was a 4 inch section of glowing green under the light.

If when the system/engine is all running and the gauges are still connected the low pressure gauge goes to zero you have a blockage. Unlikely.

Now for another important part. The system will most likely work now so take a clean jar and start collecting water condensate from the evaporator housing drainpipe. This can be tested with a uv light and any leak in the evaporator may well be revealed. If you don't collect any water and the system stops working you will not be able to check the evaporator for leaks without taking it out and shining a uv light directly onto it.

These are very simple sysems apart from the electrical side of things but if the fan is blowing you should get cold air.

What I have learnt is not to trust the experts and had I had my own uv light I would have found my leak straight away.

I don't know if yours is a 12 or 24 valve but I'll post in a bit to let everyone know how difficult it is to repace the single bulkhead pipe on the 24 valve.

Good luck
Frank

 

[frank rabbets]

The pipe was a nightmare to get off.I had to make a special sapanner to get the bolts out then put them in the lathe and turn 2 threads off each so that I could locate them in the captive bulkhead nuts. Had to drain the system. Getting the bolts out may be a lot easier with the rocker cover off!

Frank

 

[Justin_Elliott]

Thanks for the help Frank - I have a 12 valve...

I'll let you know I get on... It looks like I do have a green dye, and I think I can see some potential leak points - although at first glance it appears to be corrosion free, so i'll put a UV light on my shopping list and tackle the joints one by one!

As for the dryer, I presume this has to be an OEM part?

 

[frank rabbets]

Alternative dryers are available and I used one of these.

Frank

 

[Jon Wildsmith]

I bought a condenser and dryer from http://www.autoairconparts.co.uk, yet to fit them but they seem decent quality and sensibly priced. If you wait a bit longer I'll fit them and tell you if they work

 

[frank rabbets]

Just had a rereregas and I am confident for the first time that my aircon will be reliable. The problem with the original return/low pressure pipes from the evaporator is that they get covered in water condensation and this soaks into the absorbent fibreglass bulkhead lining keeping the pipes wet. Obviously any road salt makes the corrosion worse. The new pipe I have is different shape to miss the lining so fair play to Toyota.

Thanks for everyones' interest and help
Frank

 

[DaveN]

I massaged mine a little, and put spacers behind the supports to keep it away from the bulkhead.

Unfortunately, after a couple of years it started leaking again, as there was a tiny imperfection in the pipe that turned into a pin hole. Fortunately I have a special brazing kit for ally a/c pipes, and managed to braze it up.