We're in the middle of a heat wave (topping out around 98-100 the last few days). My wife was in NYC this afternoon to pick up her mother from JFK airport. She reported to me that the AC was no longer blowing cold air. There were no strange noises or smells coming from the vent. I plan to check out the coolant levels when she gets home and replace the cabin air filter. I've driven this car for about 500 miles over the last week, including last night when it was 95 degrees and very humid and had zero issues with the AC. In fact it was so cold in the car, I had to turn it to minimum for a few minutes. No check engine lights came on, and no other warnings to report. I guess if replacing the coolant and the air filter doesn't help then I'll bring it in. But I drove my car an hour before my wife did and didn't have any issue.

 

Coolant is for "engine cooling". Refrigerant (Freon) is what makes the AC cold. Can't just check the Freon at home like you do the radiator coolant.
You should check to see if the AC compressor is engaging (I'll bet it's not) and then proceed from there.

 

First, do you understand how the temp knob works? If you are using the AC it should be all the way Counter-clockwise in the blue too add a heat component turn the knob toward the red. I point this out because both my wife and my neighbor think it supposed to be centered at the red/blue junction.

Then check to see if the compressor pulley is engaged.
The drip tray drain may be clogged if water is draining on the floor.

 

That's the first question I asked my wife. I told her to send me a picture of how she had it set up. The AC knob was all the way to the blue. The AC compressor pulley seemed to be engaged, so I'm wondering if the system just needs a recharge. I don't think I've ever had that done with my car.

 

"Seems to be engaged". The pulley (outer part) will turn any time the engine is running. You need to see if the compressor clutch (inner part) is engaging. That's what turns the compressor. {It is a pump and has to be engaged.}
System need a recharge ? Only if you've got a leak. Then you would need to fix that 1st. AC freon charges don't just need a recharge for no reason.

I suggest a good repair shop. I used to work on auto AC's. Trying to fix one is not for the amateur or unskilled in automotive AC.

 

So I brought my HHR to firestone this morning to get the oil changed and have them do an AC systems check. The compressor did appear to be engaging to me as I was still getting high pressure air coming out of the vents, it was just warm air and I also visually saw the compressor engaging. Firestone thought that the likely culprit was a slow leak somewhere and hooked it up to their machine to try to identify the leak. They just called me back and said they weren't able to identify a leak and think the problem could be electrical. They are running a diagnostic on it as I type this.

 

It could be the blend door actuator

 

The compressor engaging or not has NOTHING to do with air coming out of the vents. Vent air is controlled by the electric blower motor.
There is no machine you can "hook up" to identify a leak. Hooking up manifold gauges will tell you the status of the freon charge...Full or low. Not identify the leak.
Electrical what ? If the compressor is engaging as you stated and the blower motor is blowing air, that pretty much rules out electrical.
Take it to an AC shop.

(I think some of the info you're relaying to us may be inaccurate or wrong)

 

Read thru this George and I agree with what you say.
Sorry to say this but the person doesn't know apples from oranges.

 

I'll be the first to admit that I don't know much about cars. I can change the cabin air filter, windshield wipers and rear turn signals. I'm a button pusher by trade, spent 6 years in the Navy working in operations. So my troubleshooting skills are with computers and weapons systems. Not with cars. I have not yet been able to call firestone, but when I get there after leaving work today I will fill you all in on what the report says.