Got two issues noted at just about the same time. First we had the A/C charged at the garage because it wasn't blowing cold air. When we picked it up it still didn't work. This happened last year at the same garage and when we took it back they added a can of 134a and it worked. So, instead of going back I added a can of 134a. It worked then worked. Then it happened...

After 2-3 days of the A/C working great we went out one morning and started the van. The brake warning lights on the van - both the (ABS) & the one that says BRAKE with the P + ! in circles above it - stayed on after the other lights went out. These lights stayed on until you actually drove the vehicle for a few feet. On that same drive we also noticed the A/C no longer worked, and a strange - almost a buzzing type - noise coming from either the dashboard or under the hood.

Ever since then and for 2-3 days now it is the same noise, lights staying on until you start driving, and no A/C. Brakes seem to work fine, but no A/C, and that same hard to describe noise. Opened the hood and listened and looked around and the sound appears to becoming from the back and center of the engine compartment - maybe the "H-Block"? or something on the back of the engine.

Now I don't figure the two problems are related, but they really did occur at the same time. Any ideas? I did try jumping what I think is the pressure transducer off the H-Block to try and get the compressor to spin but it didn't. So is this one problem causing the A/C & brake light issues, or what might be each problem?

Thank you in advance for any help!

Went out and took another look with a helper. I'm starting to think the two issues are unrelated, and also that there is certainly something with the brakes even though they seem to work fine when driving. Here's what we've got now:

With the engine running when you step on the brake the 'buzzing' noise seems to change pitch slightly. The noise seems to be more towards the area of the master cylinder area. We shut the car off and started talking. Then we thought about starting it again and when the key was turned to on the noise started even before the engine was started. Then we turned the vehicle off. We then turned the key to the on position with out starting the engine and that noise was there. Now without the engine running we found it was definitely coming from the area of maybe the master cylinder, and what appears to be the brake lines coming out of it are vibrating with the noise.

So the more important issue I would think is what is the heck is wrong with brake system that would make it make this noise constantly – even without the engine running, and we'll fix that and then try to figure out the A/C.

Thanx again!

Unsure what you got, but I'd say it would be the ABS unit. When a car is skidding and you brake, the ABS unit pulsates the braking by overriding your foot pressure every 1/4 sec or so allowing the wheel to turn. The ABS unit does whirl or buzz when it is doing this. It operates when the wheel sensors indicate one of the wheels are not rotating as fast as the other and your foot is on the brake pedal. You could check the brake pedal switch and the wheel sensors that they have proper connections.