Intermittent warm/cool AC

combhua · Post by **combhua** » 15 Jun 2016, 08:32

2007 Volvo S40
Just noticed the AC goes warm after a few minutes. If I turn it off for a few minutes and then on, I can squeeze out a few more minutes of cool air. Unscientifically, it feels like the hotter it is outside, the longer I've been driving, or the harder I try to run the AC, the worse it gets (the intervals get shorter and shorter).

I would appreciate any guidance on troubleshooting this and determining if I can fix it myself.

In the meantime, doing a little research, I've seen suggestions on needing more refrigerant as well as one to check the AC relay. I have some questions following those paths:
1) I think I can buy one of those canisters of refrigerant at Autozone or something similar and use the gauge to determine if my refrigerant is low. Is that a valid method of troubleshooting? If so, seems valuable to keep one of those gauges around for checking this in the future.
2) I looked around at IPD for an AC relay, but only found multipurpose ones (like https://www.ipdusa.com/products/8762/11 ... pose-relay) and wasn't sure how to determine what part to get.
3) Other than ordering a new relay, is there another way to troubleshoot and see if it's the relay before ordering the part and waiting a few (hot) days to find out if that was the culprit?

More generally, I recall things like Chilton manuals. Is that still a thing or are there better alternatives these days for doing some DIY repairs?

Thanks!

combhua · Post by **combhua** » 27 Jun 2016, 23:47

As a follow up for others that may find this thread:
TLDR, they replaced the compressor. ~$700

A few notes:
- Checked the refrigerant pressure by purchasing one of those cans of with a gauge at Autozone. It was fine. Someone also explained if the refrigerant was low, the temperature would be more consistently warm. Not sure how accurate that is.
- Took it to a local shop and they couldn't repro it. It required 20 minutes of driving and then would go into a few-minutes-at-a-time cycle
- Once I showed them how to repro it, they replaced the compressor
Now the AC works consistently, but there's a weird buzzing noise when I accelerate at low speeds where the compressor would be. I need to make time to take it back to the shop.

Post by **MadeInJapan** » 28 Jun 2016, 08:54

I have the same model year S40 as you but really have no idea on your issue. I do recall a similar issue with another volvo...the system was actually freezing solid and not allowing air to flow and so it would turn off and cause warm air to blow until things thawed out and then the cycle started all over again. You might do a search on this scenario and check yours to see if it is actually freezing solid in it's on-off cycle. I'm not sure if replacement of the compressor is the solution or not, but in your case, since you already did that, I hope it solves the issue...The buzzing sound- sorry, I am lost again!