Just got this car 2 weeks ago and things haven't stopped yet. Ac would start out cold then blow warm. I found an ac compressor "ghetto" fix online. Figured I'd try it out before I replaced it. Well..... I took it for a drive but not long enough to see if it fixed the ac problems. When I got home and turned the car off I heard an awful noise coming from my car. I figured I screwed up the compressor until I lifted the hood and realized it was coming from the silver cylinder thing in front of the battery area. It made the noise for a little bit after the car was turned off. I googled it and it looks like it's the brake booster vacuum pump, not sure what it's called. Is the AC compressor connected to this thing? What exactly is it? What does it do?

 

The power brakes are powered by vacuum. Really, they're powered by the atmosphere pushing on a big diaphragm that has vacuum on this other side of it. This is traditional for powering power brakes, because on most cars, the boring kind especially, the engine itself provides lots of vacuum for the taking. This does not work so well on really high performance cars, nor diesels which don't run under intake vacuum at all. So the vacuum pump is a useful add-on for turbo cars that don't run under enough vacuum enough of the time to give reliable power brakes. It would be designed to create a vacuum in the power brake booster itself. That stays evacuated all the time during normal driving.

You can power brakes using other methods, and some vehicles do power them off engine-driven hydraulics or electric-driven hydraulics. Big trucks use an air compressor.

Not really A/C related.

 

Your AC woes sound like the compressor clutch needs to be reshimmed. what happens is when the gap gets too large (ie over .8mm) the clutch overheats and cuts out. when it cools it works again for a bit. You can reshim to get it back to .3 to .4mm without opening the system. Not sure if you tried the "bread clip" trick :-) but essentially it does the same thing temporarily.

 

Thank you all for your help! I did a version of the "Bread clip" trick and all seems to work so far....for now. I ordered a new vacuum pump last night, cleaned the throttle body and MAF Sensor yesterday. Busy day! I notice a low whining noise while the motor is running and after using trusty google it seems that could be the vacuum pump. I am hoping. This morning though I felt my car shudder when the AC kicked on. I felt it twice while sitting in a drive thru. Is that still my AC compressor or is that something else?

 

If the vacuum pump is running all the time, replacing it likely won't fix it. Its probably a shorted vacuum switch.