Just picked up the car after shop replaced AC compressor and as I arrived home the low coolant warning light came on. Expansion tank must have been virtually empty because I just put 2ltrs in.

Any ideas? Does replacing the compressor involve removing any coolant that they did not replace or does a newly operating AC system use any coolant? Maybe it’s not related but a bit disconcerting!

 

The A/C system does not use coolant but they might well have had to remove a coolant hose to gain access to the compressor.

Richard

 

Top up the coolant with the correct type, then use a cooling system pressure tester to determine if there are any leaks. The AJ133/AJ126 become very cross if overheated.

 

[QUOTE=RichardS;2810702]The A/C system does not use coolant but they might well have had to remove a coolant hose to gain access to the compressor.
Also disconcerting if they did and then didn’t replace the 2ltrs of coolant!

 

and if there’s an air block…

 

Finally got it back into the shop today after being shut down for the hols since Dec 20. They did the coolant leak test and concluded a faulty cap! (200 psi). Absolutely no coolant staining or wetness around the expansion tank so I have some doubts. It took about 20-30 mins for the warning light to come on and said tank was empty during the original incident. Next day same symptoms. Since then I’ve done a couple of 15 min runs and had to put in about half to 1 liter each time to keep it full.

Im really hoping it is just the cap when I get it back but what do you guys think, is it possible to lose that much that quick through the cap with no smell and no staining?

 

One time I purposely ran the engine with a loose cap, so as to slow down the loss of coolant. I doubt the coolant is going into the oil? Into the tranny? Onto the floor?

 

If there is no staining or residue around the cap, I would be extremely surprised if you could lose that much coolant without some evidence.

It does sound very much like the rubber pipe in the valley has split. It is extremely common and, with mine, the coolant ran straight into the bellhousing so there was absolutely nothing visible unless you crawled under the car next to the gearbox, which is much further back that most people would look.

Richard

 

yes but wouldn’t that show up on the leak test?

 

I do agree that it should do but there is a huge volume of coolant being lost that surely it would show up around the header tank unless it was being lost into the combustion space through the head gasket or into the exhaust system through the EGR valve. However, that would also show up on a pressure test and would produce a lot of steam in the exhaust. It's a real puzzle. There must be a trace of it somewhere but, for some reason, it just isn't being seen.

Richard

 

Maybe part of the puzzle is that it started the day I got it back from the shop when they replaced the AC compressor. I said they disturbed something and they said they didn’t. I’m still thinking they left a loose hose then fixed it today and said it was just the cap to avoid embarrassment. Who knows!!

 

If the "new cap" has actually stopped the coolant loss, then I think you've hit the nail on the head.

Richard

 

Garages - never ever ever ever admit liability

The onus is on the customer to have evidence that they did screw up. I would take this car to a garage elsewhere and get it examined and not drive anymore until you have a correct diagnosis