Took my 93 850 to the volvo shop and got the system vacuumed and refilled. The air is super cold and the AC runs fine but as soon as the outside temperature reaches 29C and above, the AC only runs for about 10min and then i have to shut it off. When i restart it 10min later, it'll only run for another 10min and so on.....

 

How long have you had the car? Have you had to charge it before? It sounds like you have a leak and your compressor is cycling on and off. You say it stops above 29C, will it continue to run if it is below that temp? Could be a temp sensor problem or thermostat problem.

 

i've had it for 2 months now and yes it does continue to run under 29c or so. constantly. As soon as it's above that, it only runs fr 10min...on and off with hot air coming out in between. Could it be the low pressure switch and could i short the compressor so it doesn't shut off or the switch.

 

I wouldn't think that it would be the low pressure switch itself, either thermostat or temp. sensor that senses the temp and tells the compressor to cut on. You will have to wait for tech regarding running a constant to it.

 

If you jump the low pressure switch you will have to watch the air flow.If the low pressure switch doesn't cut off the compressor it will freeze the evaperator.Then the air flow will go to almost no air till it defrosts.

You might also have a bad compressor.When you drive and it cuts off try to check for power at the compressor.If you have power at the compressor then the compressor is bad.

Check that first.

 

But how could a compressor be good under 29 or so degrees celcius and not work right just above it. Wouldn't it make sense if it was some type of temp sensor. is there on on these systems?

 

It could be but on these compressors when they get hot when they are old they kick of from overheating.It happens from a worn clutch.

If it is cool outside the compressor cycles alot and doesn't work hard enough to overheat.
When it is hotter it takes longer to cool the car.

 

Could the inside sensors be acting up?..the ones around the door grip area? i've seen something about that somwhere that when they get dirty..the ac malfuctions? How much is a cluth replacement usually?

 

If the sensors in the grab handles(In cabin temp sensor) act up it will post a code in the system.

I reccomend replacing the compressor.Most of the time when just the clutch is replaced the compressor goes bad shortly after.Then you wasted the money for the clutch.
It is pretty expensive I think like the $300.00 for just the clutch and $500.00 for the compressor.
Im not 100% positive on the price!

 

Is the compressor clutch an easy diy fix ? i was considering getting a used compressor instead. They're going for 250$cdn up here and they're guaranteed 3 months. The system doesn't have to be refilled right if i change the compressor myself?

thanks

 

The clutch can be done.The thing that is a pain in the butt is that it needs to have a special space between the outer part and the inner part.
If you replace the compressor your self you will need to drain and refill the system.

 

Wow. maybe i'll just go for the clutch. I just had the system vacuumed and filled at the volvo shop. I don't feel like spending another 400-500$. I waiting on one guy who's going in the shop this morning to change his clutch for the same problem and if it works i'll do the same.

Thanks, your help is greatly appreciated.

 

No problem keep me posted on how things go.

 

I was thinking. If you say the compressor is the problem, then why do people change the compressor clutch if it's the compressor that's overheating. What's the relation between the two.

 

Most of the time the main problem is the clutch.But I have seen it dozens of times that they replace the clutch then the compressor goes.Then the $300.00 someodd dollars is wasted.By the time the clutch acts like this the compressor has had many many hours on it and is at about the end of its life as well.
Thats why I reccomend replacing the compressor.

 

OK so a compressor will come with it's own clutch then? if not , what's the use of keeping an old malfuctioning clutch with a new compressor?
Some specialiste suggested that it might be a condenser problem. HE doesn't see why the compressor would malfuction in high temp and work fine in cooler temps. He thinks it might be that or a sensor of some type. Man this ac is driving me crazy. High temps and extreme humidity up here now.

 

Yes the new compressor comes with the clutch.
You can test it your self as long as you have a test light and know how to use one.
When it happens test for power at the compressor.
Another thing you can try being Very careful when it acts up try tapping the clutch on the compressor with a stick and see if it comes back on.

I had the same thing happen to my cars many times.If you keep the fan speed down pretty low it will take longer for it to act up.When on a lower fan speed the compressor will cycle more that if on high fan speed.

 

I've just read somewhere that there is a temp switch on the compressor. Some type of gold plug and can be bypassed with two wires.
Is this true and can it damange the system. He mentions that his system was acting up the same way and they found out it was the temp switch freaking out.

thanks

 

You can unplug it and put the wiring together and give it a try.
I almost forgot about that because I haven't had one of those in years.

 

Well, i took to an AC specialist yesterday and he noticed the clutch gap was way too small (2-4 millimitres) He tried to adjust it but he couldn't so he told me he had to take the whole compressor out to do it. That would be a half day job.
Is there no way to adjust the clutch gap from underneath the car?