Hey all, I recently bought a 2002 C5 base coupe 6-speed, with 85,000 miles, auto climate control, and A/C not working. When I set the temp to low and select auto the fan blows strong but I get no cold air. The compressor is not kicking on. Also when I select manual AC, the orange light in the AC button comes on momentarily, and goes out. Again, the compressor does not come on. I am not able to even attempt an auto parts store bought AC recharge since the compressor never comes on. I know there is a relay in the fuse box under the hood for the AC system, but I can’t pull it out and I don’t know how to test it. Could that be a culprit? Maybe I have a bad compressor? Anyone have a similar problem and know if there is an easy solution, or do I have a bill coming my way for hundred of dollars at the repair shop? Thanks for any advice or suggestions.

 

Most likely low on charge.

Don't add refrigerant into the system using one of those auto parts recharge kits. They suck. At minimum you need manifold gauges to do it properly.

More realistically, AC systems are obnoxious to DIY. I've done it before, and the most recent time, I just gave it to a shop and told 'em to fix it.

If you really wanted to DIY it, you need to do roughly the following.

Watch a youtube video on how manifold gauges work, how to plug 'em in, how to use them.
Get or rent manifold gauges.
Check the pressure of the AC system on both low and high side.

If you have decent but low pressure:
Note the temperature and humidity, and get a chart telling you the target pressures at the current temperature and humidity.
Get a can of refrigerant, or two. You may want the stuff that is impregnated with glow-under-UV dye.
Start the car, let things come up to temp, turn the AC "on" (even if it refuses to click on), and follow the temp-and-humidity chart to fill up the system properly.
At a certain pressure, the pressure switch will tell the AC clutch to engage. Wait for pressures to equalize, then continue to fill up the system until pressures are correct.
You should be good to go ... slow leaks are common enough, and actually using the system is often enough to get seals slightly lubed up and sealing tight.
However, you should check once in a while to see if the system is losing pressure. If it is, figure out where from. Get that fixed.

If you have no pressure:
You're leaking refrigerant somewhere kinda bad. You also may have moisture in the system.
You should really just give it to a shop to fix.
If you really wanna DIY, get a vacuum pump.
Pull vacuum for a half hour then turn the pump off off, check to see if it stopped holding vacuum after another half hour.
Does it hold vacuum? If so, your leak may not be that bad. See above.
If it does not hold vacuum, you can attempt a fix yourself (often an o-ring that you can replace.)

However, if at any time you're just putting more refrigerant in to figure out what's going on, you're putting a lot of that **** in the air (not good) and maybe breathing it in (much worse).
Because of the specialty tools (not expensive but, yknow, not really multi-use), environmental and health concerns, and generally being really ******* annoying ... I recommend giving it to a shop to fix.

 

As Gimp stated above, dont just add autozone " freeon" to your system. the ac really isnt something to diy
unless you have an idea of what you are doing. The correct charge is really important, The correct amount of oil is very important , debris in the orifice tube will cause problems and with the correct tools a shop can pinpoint a leak easily.
Your system is probably low on the charge. Due to a leak, and low on oil lost in the leak

 

This is fantastic, thank you so much for the education! I’m quite convinced now after that very informative response that I’m going to a repair shop, and I agree with you all the way that doing so is my best option. Thank you very much!!

 

You've received excellent advice and, no, those recharge kits are not the way to go

Let me just add that a DIY recharge is doable if you're careful and a little technically inclined. You just have to do it the right way.

In case you want to give it a shot, get a set of A/C manifold gauges, as mentioned above. Doesn't have to be top-of-the-line and uber expensive. One from Harbor Freight would be fine (or get a free loaner from an auto parts store).

Although not essential, a thermometer will give you a better idea of the A/C system health. You can get for around 5 bucks:


Check both pressures to have an idea of how things are. Take a look at this Post. It has detailed instructions to check/add refrigerant.

-These are the CliffsNotes:

Check your pressures against the chart below (you'll need to determine ambient temperature and humidity first). Make sure you take your readings with:

• Engine @ 2000 rpm
• A/C in coldest setting
• Fan at maximum speed
• Both windows down
• Thermometer in center air vent

When adding refrigerant, pay attention to both pressures, otherwise you might end up with the high side sky-high trying to get the low side to the chart's value.

Let us know how it goes.

 

Excellent advice all around. The information and education gained here is fantastic and truly appreciated! I think in my case, and after reading your responses, my best bet is to take it into the shop and leave it to the pros. Thank you all for your extremely informative responses!! Very happy to be a part of this forum. 👍🏼