I have just noticed the air-conditioning on the Zed I bought two weeks ago is not working.

 

Any ideas on what is the most likely cause?

 

Dave

is the belt fitted (looking at the engine its the right hand lower belt)?

It may have been removed.

is the belt fitted (looking at the engine its the right hand lower belt)?

It may have been removed.

 

Yes, the belt is fitted (to my 1995 Zed). I have compared with my 1990 Zed (which I still have and the a/c works fine) and there is a quiet 'click' and the engine changes speed slightly.

 

This doesn't happen on the non-working 1995 Zed although the light on the switch comes on.

 

Could it be a faulty switch? Fuse blown - where do I look? A/c pump knackered - is this likely?

 

Dave

Why would anyone remove the belt if the compressor wasn't knackered?

 

Sounds like it needs re-gassing. Does your irle rpm change at all when you turn it on and off?

more than likely want a regas, sounds like the pump is cutting in ok.

more than likely want a regas, sounds like the pump is cutting in ok.

 

Sorry Paul but I don't think the pump IS cutting in. The 'click' etc. I described was on my 1990 Zed, it does not happen on my 1995 Zed where the a/c isn't working. Any ideas?

 

Dave

Why would anyone remove the belt if the compressor wasn't knackered?

 

Sounds like it needs re-gassing. Does your irle rpm change at all when you turn it on and off?

 

Hi Clarkey - No, the idle speed does not change when I turn it on/off, neither do I hear a 'click' (which I do on my 1990 Zed). Any ideas?

 

Dave

Yep, if the gas pressure is too low the compressor won't engage to prevent damage.

Why would anyone remove the belt if the compressor wasn't knackered?

 

Cos some of us dont actually want such a power sapping unneccessary extra on our cars. :nono:

There is another option and that is that the relay has been removed. It should be in the engine bay fuse and relay box... on the right hand wing as you look at the car. I had to do this to my old NA when the electro-mechanical (I think) Clutch packed up. Probably isn't that but just in case....

 

HTH

There is another option and that is that the relay has been removed. It should be in the engine bay fuse and relay box... on the right hand wing as you look at the car. I had to do this to my old NA when the electro-mechanical (I think) Clutch packed up. Probably isn't that but just in case....

 

HTH

 

Thanks stricker - I've just checked the relay and it works in my 1990 car so should be O.K.

 

Quote Clarkey - Yep, if the gas pressure is too low the compressor won't engage to prevent damage.

 

Hi Clarkey - I didn't realise low gas pressure would prevent the clutch from working. I have looked closely and the clutch is definately not engaging. What's involved in getting the gas pressure up?

 

Dave

What's involved in getting the gas pressure up?

 

Dave

You will need to get the aircon regassed, find a garage advertising such services. Depending on usage this tends to be required every 2-3 years.

 

Unfortuntly the zed uses R12 gas, which is no longer (legally) available in the UK. It can be converted to R134a cheaply though.

 

Aircon regas FAQ : http://www.300zx.co.uk/forums/showthread.php?t=33691

There is always the fuse, very near the relay that you have already checked.

5 amp I think...

i think you will find it will work whether gassed or not

if the pressure is low, short out the 2 wires to the low pressure switch, the compressor should then cut in. if it does, the rest of the system is ok & needs a regas (or switch is faulty - unlikely tho ;) )

i think you will find it will work whether gassed or not

no, it won't

if the pressure is low, short out the 2 wires to the low pressure switch, the compressor should then cut in. if it does, the rest of the system is ok & needs a regas (or switch is faulty - unlikely tho ;) )

 

Thanks Paul - excuse my dumbness but where/what is the low pressure switch and what is best way to short out the two wires?

 

 

mgh297 - I've checked the (10A) fuse and it's O.K.

 

Dave

Cos some of us dont actually want such a power sapping unneccessary extra on our cars. :nono:

 

come on now, with the a/c off that pulley spins compeltely freely, extremely small amount of drag. And if you didn't want it, you would just throw the whole lot away and be done with.

Thanks Paul - excuse my dumbness but where/what is the low pressure switch and what is best way to short out the two wires?

 

 

mgh297 - I've checked the (10A) fuse and it's O.K.

 

Dave

 

on the reciever/drier IIRC, i think you can gain access through the headlamp panel, its on the left as you look through it.

 

you can short it out with a piece of wire or a split pin

If you got an after market filter, you can easily access the pressure switch through the air filter panel.

 

Spent fooking ages sorting my air con out, never found the problem, went through everything with a fine hair comb and never found it. Ended up wiring in a switch myself.

I'm really grateful for the help you are all giving me regarding my a/c problem and, because of your help, I have been able to eliminate several possible causes.

 

But I'm afraid I am getting a bit out of my depth when you refer to items such as "low pressure switch" and "receiver/drier" as these things mean nothing to me. I am reasonably useful with my hands and am sure I could cope with things that don't require too much stripping down but if I can't identify the items I am completely lost (and useless). Is it possible to provide a photo or diagram that would help me locate this switch?

 

Dave

Look through your bumper and you can see your rad. Jsut to the left is a black cylinder about 6 inches long, 2 inch diameter. Theres a black plug on that with two wires to it, one orange, one green. Bridge that out with a small piece of wire and if it runs its low on pressure.

 

But I found my tags in the switch had broke and needed soldering back together.

Heres a picture

Heres some more diagnostics you can run to check all the sensors

 

How to get into dianostics

 

here

I have EXACTLY the same problem, cheers guys.

Look through your bumper and you can see your rad. Jsut to the left is a black cylinder about 6 inches long, 2 inch diameter. Theres a black plug on that with two wires to it, one orange, one green. Bridge that out with a small piece of wire and if it runs its low on pressure.

 

But I found my tags in the switch had broke and needed soldering back together.

 

O.K. I have found it now but how do I get at the leads to bridge them? Do I have to remove the trays underneath and does the engine have to be running for the a/c clutch to work or does it only need the ignition on?

 

Dave

 

ps. my cylinder is aluminium colour and it has a label on it stating that R134a is to be used. At least that sounds like good news.