I started the car today and thought I'd leaving it running for a few minutes so that the air con could cool the inside down a bit before driving it. After a minute or two there was a sudden whoosh and cloudy steam looking stuff came out from under the bonnet! Seemed to be coming from the passenger side at the front somewhere. I turned the engine off. It hissed/steamed for 30 seconds or so and then died away. I couldn't see anything very obviously wrong (not that you can see much in those engine bays) so I started it up again and everything seemed OK, so I gingerly drove it home (watching the temp gauge like a hawk!). Every thing was fine engine wise, the only thing wrong was that the air con had stopped working. So I'm guessing (hoping) that the steam and hissing was 'just' something to do with the air con and nothing more serious. Does that sound likely? Any idea what could have actually happened/would have caused it? And what sort of job I'll be looking at to get it fixed?

Any help much appreciated.

 

Phill

Sounds like the top radiator hose pipe mate, they fracture off the radiator and you get a whoosh of steam. Had it on all 3 off my zeds at one point or another :(

Have you checked the water level. How far did you drive it after this happened.

 

Paul

I've not checked the water level as such - possibly really stupid question, but how do you check it? Have I got to take the arch liner out?

Check your rad level. If it's empty then you've boiled dry

 

Take the top hose off the radiator and check for a crack, they always go in the same spot on na/tt rads.

 

If that's alright then fill the whole system up, run the engine with the heater on to get the water through the whole system. It'll take alot to fill it.

 

When it settles check for the water swirling in the raditor. If there's no current you may have a worn out thermostat that's jammed.

 

Easiest way to test is to put the cap on, run the car up to temperature and put your hand on the raditor. It should be warm to the touch not cold. Same goes for the second (lower) pipe on the front. If that's cold the thermostat hasn't opened and you're running all the heat at the top of the block.

 

I had that happen twice on the na in the last few weeks unfortunately the build up of pressure blew the rear water pipe to pieces and it was a plenum out job to get to it.

 

Hopefully the steam at the front indicates the radiator.

 

Hope that helps mate and it's a quick 5 minute job to get that hose off the rad.

The rad cap is number 11 in this picture.

Thanks guys, I'll have to check when I get back from work.

 

300_zedx - is it not number 7 that I need to check (just read my manual!), I did have a quick look under the radiator cap (11) but couldn't see much.

 

Any ideas why the air con should have stopped working at the same time? The fan works, just blows warm air.

 

Thanks.

If this was shortly after starting from a cold engine then it is more likely your aircon just vented itself and you caused a hole in the ozone layer. You are probably responsible for all this good weather! Hope its the pressure relief valve rather than burst!

 

The 300zx aircon system runs at quite a high pressure as it is and some substitutes make it run even higher. Does it still work now? Has it been refilled before with an R12 (is it) substitute?

Thanks guys, I'll have to check when I get back from work.

 

300_zedx - is it not number 7 that I need to check (just read my manual!), I did have a quick look under the radiator cap (11) but couldn't see much.

 

Any ideas why the air con should have stopped working at the same time? The fan works, just blows warm air.

 

Thanks.

 

Number 7 is the over flow bottle, number 11 is the rad cap, you need to take the rad cap off to see if you have water in the cooling system.

You should have been able to see some water when you took the rad cap off, No 11, if not top it up.

 

Paul

Edited June 1, 200916 yr by 300_zedx

If this was shortly after starting from a cold engine then it is more likely your aircon just vented itself and you caused a hole in the ozone layer. You are probably responsible for all this good weather! Hope its the pressure relief valve rather than burst!

 

The 300zx aircon system runs at quite a high pressure as it is and some substitutes make it run even higher. Does it still work now? Has it been refilled before with an R12 (is it) substitute?

 

The car had been standing for about an hour and a half, but with the weather being as it is it was still pretty warm. I'm afraid I've no idea if the air con system has been refilled at any point, there's no mention of it in my rather sketchy service history. It wasn't working very well before - with it on, the air blew out very slightly colder than when turned off, but wouldn't have described it as 'cold'. It doesn't appear to work at all now though - blows distinctly warm no matter how you set it.

 

Number 7 is the over flow bottle, number 11 is the rad cap, you need to take the rad cap off to see if you have water in the cooling system.

You should have been able to see some water when you took the rad cap off, No 11, if not top it up.

 

Paul

 

Thanks Paul, so do I pour the water into number 11 (rad cap) and not number 7? Do I need distilled water or can I just use tap water (with anti-freeze)? The level could be low regardless of this incident as when I last got it back from Zedworld they told me to check it and top it up after a couple of days, but I forgot :slap:.

One obvious indication that the aircon is de pressurised is to have the engine idling and switch from auto to econ to auto. You should hear the engine revs pick up when you switch to auto as the extra load for the aircon compressor is carried. Once the pressure is gone the system locks out the aircon compressor to save damaging it and the revs will not change at all.

 

A working system when switched on to auto will quickly heat up the condenser rad in front of the radiator. You can also see the coolant or lots of bubbles if its low in the sight glass window.

You say this, but i took my compressor off and mine permanently alters revs to compensate, whenever i switch Economy on or off. I leave it on when im booting it though, it stalls after boost otherwise, presume its the BoV's ^^

 

 

One obvious indication that the aircon is de pressurised is to have the engine idling and switch from auto to econ to auto. You should hear the engine revs pick up when you switch to auto as the extra load for the aircon compressor is carried. Once the pressure is gone the system locks out the aircon compressor to save damaging it and the revs will not change at all.

 

A working system when switched on to auto will quickly heat up the condenser rad in front of the radiator. You can also see the coolant or lots of bubbles if its low in the sight glass window.

Thanks Paul, so do I pour the water into number 11 (rad cap) and not number 7? Do I need distilled water or can I just use tap water (with anti-freeze)? The level could be low regardless of this incident as when I last got it back from Zedworld they told me to check it and top it up after a couple of days, but I forgot :slap:.

 

Use number 11, you wont top the cooling system from the overflow bottle. I have to say I've never used distilled water to top the cooling system up, always used tap water.

 

Paul

I at last got chance to check the coolant levels this evening. It took about 1/2 a litre to bring the radiator up to the brim, and another 1/2 litre into the reservoir to bring that up to the 'H' (full) line. So it wasn't dry, and as I said, Zedworld told me to check it a while ago but I never got round to it so I would have half expected it to be a bit low.

 

One obvious indication that the aircon is de pressurised is to have the engine idling and switch from auto to econ to auto. You should hear the engine revs pick up when you switch to auto as the extra load for the aircon compressor is carried. Once the pressure is gone the system locks out the aircon compressor to save damaging it and the revs will not change at all.

 

A working system when switched on to auto will quickly heat up the condenser rad in front of the radiator. You can also see the coolant or lots of bubbles if its low in the sight glass window.

 

Thanks WillieO. I get the change in engine revs when switching as you say, but the air temperature coming out of the vents doesn't change at all (I had the temp set at minimum to test). I also felt the little radiator in front of the main one and that was not warm at all.

Sounds fine, just keep an eye on it for a couple of weeks, go for a short run and check the level when it's cooled down.

 

Paul

Agree with Willieo, the air con sytem valve vent has triggered, this now needs replacing and checking why it went off, most likely is failure of the condensor fan leading to excessive high pressure in the system so the safety valve did exactly what it was designed to do.

 

 

Jeff TT