Hi Guys,
I searched the forums but was a little surprised to not find anything pointing to my problem. Hopefully someone can point to a thread already out here...


My 2010 SS has 59,xxx miles and the a/c didn't cool at all (temp gauges ARE working properly). I took it to the shop I trust because I figured it needed Freon, and they worked on it for an hour. They said that the charge was only a little low (I noticed bubbles in the low-side pressure Schroeder valve last week--but leaking valve is now secondary problem), but the real problem seemed to be that the compressor clutch relay wasn't receiving a signal.


They suspect the relay/fuse/computer boxes over on the driver's side of the engine compartment. They recommended that I check with a dealer to see if there are any recalls on the issue, as they thought they'd heard of a loose-connections problem with these cars (they specialize in Saabs, Subarus, and such). If not, they feel confidant that they can repair it if necessary (they refused to charge me for the diagnostic work - another reason I trust them).


So now the a/c cools sporadically - maybe 10% of the time the air gets cool. No rhyme or reason to its function/non-function (e.g. highway speeds, low speed, outside air/recirc, etc). At least it's only 97 degrees around here and a low 80% humidity.


Thanks in advance for your assistance!


Sweating In St. Louis

 

It's the same car as a Saab 9-2.

Loose connection could be the fuse box halves coming loose.

What is the coolant temp?

Any OBDII codes?

Sounds like the guys didn't feel like messing with it. Did they test the clutch? The pressure switch? The wiring? The relay?

 

Thanks for the great questions, Don! Sorry I forgot to post those other pertinent details (i'll use the "it was my 4am fog at work" excuse).

- NO codes (did not scan for "hidden" codes if such things exist), no Check Engine Light
- temps are 192-199 as always for this car

You're right in a way about the guys not wanting to mess with it: they have a 3-week lead time to work in cars, but allowed me to "squeeze" in because they figured it could be a quick vacuum/charge a/c job and it's hot here (mercy). So they definitely did more than they hoped to do in taking an hour to identify the bigger problem. I don't know for sure specifically which electrical components that they checked though - I'll give 'em a ring and ask.

Thanks again - maybe I'll try to snug up connections on those fuse-box halves if I have time this evening before work.

 

"sporadically" means sometimes it does work. Does it work or not?

Some codes will not set the CEL until they happen again, but get stored waiting for a re occurrence = hidden. You have to know what you are looking at.

The compressor signal comes from the ECM with inputs from the coolant temp sensor, the refrigerant pressure switch (my guess) and the serial data lines from the BCM.

It gets to ground at the LEFT strut tower.

 

How old is the thermostat? And the Dexcool?
It could be the Dexcool is getting on and is slowly causing the thermostat to open oddly , affecting the A/C performance!

 

In my first post I wrote that it seems to work less than 10% of the time requested to cool. But since the drive home from the shop (about one or two hours' of driving) I've left the a/c button to ON and it seems more accurate to say that it only cools for less than 5% of the time. I suspect "sporadically" should be changed to "rarely."


I had not asked the a/c to work until last week - so this may have been a problem for some time without me knowing.


It doesn't have Dexcool in it, and really don't know about the T-stat life... does the consistent 192-199 temp reading indicate proper function? I've heard that a change back to Dexcool should be on my ever-growing list of To-Do's, in any case.


I'll check that ground on the left strut tower too... thanks much guys!

 

Wrong coolant and incorrect thermostat can definitely cause issues!
If the ECM doesn't get the correct signal from the temperature sensor the TCM and the BCM can react strange!
I'm aware that most times a code will show up P0128, but not always.
The correct AC Delco stat is a 180 degree.

 

It's how fast the temp gets to 180F.

 

Seems like it takes about 10 minutes to get up to the 192-199 range (although on highway at 95 degrees yesterday I noticed it creeps to 203, then goes back down at 40mph).

Those seem (to this HHR novice, anyway) to be normal operating temps and timing (10 minutes to full temp), no? I'm happy to flush / replace the antifreeze and t-stat, but I'd rather spend my limited time on more likely culprits (unless this DOES seem like a likely culprit).

Called a Chevy dealer today - they said that there are no outstanding recalls on my particular car.

Wiggled the fuse boxes but couldn't really see how/where specifically they might lose their connections. I double-checked the wiring harness looms that go in to the sides, seem secure. The ground straps near the driver's side strut tower are secure and look perfect.

Of the 40 minutes driven since yesterday, I had two 30-second sessions of cold air (one at highway speed, one at 45mph).

Note to self: check a/c function in car BEFORE summer arrives.

 

Plug "hhr fuse box youtube" into GoOgle and you will get this: