Car A/C troubleshooting: delayed operation

I’ve been a reader of TSD for a long time. Now I’ve finally signed up in hopes of addressing one of the most troubling issues of our time: what the heck is wrong with my car’s air conditioning and why does it make me suffer so? Ok, maybe this is of great importance only to me. . . But with temperatures in the high 90s and humidity at about 27,000% (give or take a bit), this issue is indeed very much on my mind!

Here’s the situation: I have a 2002 VW Passat with the 1.8T engine that has been entirely trouble-free until now. Currently, when I press the A/C button, the light comes on and the extra fan under the hood turns on. However, the air from the vents does not cool down right away. Instead, at some random time later, the a/c suddenly begins working and the air gets cold quickly. The time delay can be from a few seconds to over an hour and it seems to be completely random. When the a/c does kick on, it works great and operates perfectly until I either turn it off (not likely in this weather!) or I shut off the car. When I restart the car, the a/c has another random time delay before it will operate.

Now, I’m pretty handy with a wrench and I do my own oil changes and other light car maintenance and repairs. But I don’t know too much about the electrical systems in modern cars. It seems to me that the problem here is not in the a/c system itself, but in the activation of it. I believe my car has an electromagnetic clutch that engages the a/c compressor which is run via belt from the engine. What is the likely failure point here? Are there relays that could be failing or is it likely to be the clutch? Could it also be the compressor itself?

I’d like to find out if this is something I can fix on my own. . . (crossed fingers) Any direct help anyone can give me is greatly appreciated! Also, if anyone can reommend another resource for information, that is appreciated as well. Thanks all. . .

It’s not a random time delay. Annoying though it might be, it happens to pretty much every car. OK so it’s, what, 95 degrees out? Around there? After only 3-5 minutes outside idling, the car has alread yreached about 150 degrees. If your car’s een outside for more than 20 minutes, I’d say it’s at over 200. And most people, on days as hot as that, like the inside of their cars to be, what, around 65-70? Your car needs to cool down to that temperature before it can start cranking out the A/C. That’s I don’t turn on the A/C in the car until about 10 minutes into the ride. I roll down the windows until then. In my car, IDK about yours, but if I turned on the A/C immediately, I would be greeted by a blast of 100-degree air that’s difficult ot breathe in and promptly start sweating buckets. Plus it’s even harder for the car to cool down when the engine is on and all that.

If the A/C takes a really long time to cool down, your car could be overheating. I’m not exactly sure about what to do there, sorry.

Welcome to the SDMB Wonderwall6129!
But to reply to your post, in a word, no. It doesn’t work that way.
Getting back to the OP. There is generally a 5-10 second delay after engine start on modern AC systems to allow the idle to stabilize before the compressor engages. Obviously you are not experiencing that. :slight_smile:
Off the top of my head, I can think of two problems you might be having. first is electrical and the second is leak causing low refrigerant.
Do this, the next time the car acts up (No AC) stop and open the hood, and look at the compressor. Is the clutch engaged even though the AC is blowing warm air? Is the clutch cycling quickly?
If the answer to either of these questions is yes you probably have a leak, and are low on refrigerant.
If the compressor is not engaged, it is most likely an electrical issue. Possibly a poor connection or a bad relay. If you can find the AC relay, you could try replacing it.

I drive a Hyundai worth less than my pool cue that blows cold air the second I turn it on, regardless of the heat of the car’s interior. I don’t think your assertion applies to most every car.

Thanks for posting, but this doesn’t fit the symptoms. Maybe I should have made it more clear that this is a NEW problem. I bought the car new so I’ve weathered a number of hot summers in it already. In prior years, the a/c would at least start blowing cool air within a few seconds of me turning it on.

The car acts up everytime I drive it lately! The compressor assembly is on the lower side of the engine, so it’s a little hard to see. As far as I can tell though, the clutch does NOT engage when I press the a/c button. Also, once the a/c does finally kick on, it stays on and cools well. It sounds like this points to an electrical failure then. . .

I’ve been trying to find out about the wiring of the a/c system (including relays), but I haven’t had any luck so far. I went to the library to take a look at their collection of Haynes manuals, but they didn’t have the one for my car. None of the auto or bookstores seem to have the right one in stock either. I did look at a manual for the VW Jetta while I was at the library, and I noticed it did not include wiring diagrams for the a/c system or any info at all on the relays. I’m hesitant to order a repair manual if it isn’t going to give the info I need.

Rick, I’ve gathered from reading the board that you know your stuff when it comes to auto repair. Do you know if there is a resource I can check that is free? Or if there is a reasonable cost resource that would definitely have info on the wiring and relays for the a/c system?

Thanks for your help so far everyone. I appreciate everyone taking the time. . .

The technical term for the compressor being hard to see is “Sucks to be you.” Anyway you look at it you are way closer to the compressor than I am. Maybe if you held your car up to the keyboard, no a little more to the left, now up a bit. Nope, sorry the light just isn’t right.

Over half a lifetime in the car business will do that. :slight_smile:
You might look around the net for a VW board. The other suggestion I have is look in the owner’s manual and see if they list the relays and their locations. Often times a car company will use the one relay for A/C and an identical one for another function. Swapping them is a quick way to check for a relay problem. If your car has a combo relay and fuse box (often under the hood) read the underside of the lid, and see if they ID the relays. Also if you have not done so, change the fuse for the A/C. It is a real long shot, but you can get a intermittent fuse.
Whoops I guess that was more than one idea wasn’t it. :o
Good luck

I had this same thing happen to me several years ago. The problem only ocurred in the same fashion. Once it kicked in everything was normal, but until it did, I had to keep the windows rolled down. Turns out that the clutch for the Compressor was sticking. If I hit a bump in the road or if I tapped the compressor it would go back to working. This may be your problem. I don’t know if you can replace just that part of the compressor. I ended up buying a new compressor and installing it. After that there were no more worries.