Looked into general AC issues for Volvos. I realize that it can get complicated and be much more than just low coolant. I was lucky in that my wife's 940 was low on coolant and a top-up fixed the AC function easily. My c70 is not so easy...

I get intermittent cooling from the AC. Works fine for a while, then starts to blow hot air instead. Can't seem to sort it out. Works better when the car has just been started. Works a bit better on the highway. After it stops working well, it *really* doesn't work at all.

Thought it might be low coolant (easier, quickest fix) but the system refused to take any coolant at all. I got blow-back from the low-pressure valve, so I gave up quickly. I used the same can of coolant on the 940 and it went in like I was feeding a hungry baby...

I read that over-pressurizing an AC system can be death to your AC system. I'm worried that the previous owner may have done just that.

I let the car sit for a few days, and found the AC worked (for a while) when I restarted the car. But it quite working again pretty fast.

I did notice that the compressor clutch was cycling quite a bit - many times per minute until the car had been driven a couple miles. That worried me.

If the problem is not too little coolant, what else could be the issue? Bad compressor? Bad electrical contacts somewhere? something else entirely?

This car has high miles and a small raft of small issues, but I do like it quite a bit and want to keep driving it for some time.

Any help/advice is appreciated.